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Tuesday, 28 March 2017

A Car Battery Monitor Circuit Diagram

A close call on the road can really focus your mind on the importance of having a battery monitor in a car. I had been enjoying a pleasant week of travelling around the countryside at a leisurely pace and taking in the beautiful scenery each day. It wasn't until the final day, with the big rush to return home, that I had to drive at night.My home is deep in the country and on the road I was travelling the closest petrol station may be 80km away. I was travelling through an area that is full of open-cut coal mines and large heavily loaded semi-trailers constantly pound the roads, travelling at quite high speeds. It was around 8pm at night and everything was very dark no street lights or house lights anywhere.

Just as I was going up a hill, the lights began to dim and the engine coughed. A large semi-trailer loomed in the rear-vision mirror as I pushed the clutch in and tried to restart. My speed was falling rapidly and my lights were blacked out - I was like a sitting duck in the middle of the road, as the semi-trailer came rapidly bearing down on me. I just managed to pull the car off the road, as the semi-trailer came screaming past, missing me by inches! After calling for assistance from the NRMA, the problem was found to be a fault in the alternator, which was failing to charge the battery. The battery voltage had been falling under the heavy load of the lights and at the worst possible time, there was not sufficient power for the lights or the motor.

After the initial shock wore off, I put on my thinking cap to come up with a PIC-based solution to the problem. What was really needed was a display and a buzzer, to get my attention should the voltage fall outside a specified range. So my design criteria was set, a series of LEDs could indicate the voltage and a buzzer would also be used to warn of problems.

Main Features:

Visual indication of battery voltage
Audible warning when voltage becomes low
Screw terminals for easy connection
Simple and easy to build

Circuit details:

The circuit is based on PIC16F819 18-pin microcontroller which has an analog-to-digital (A/D) input to monitor the battery voltage and outputs capable of driving LEDs directly, to keep the component count down. There are seven LEDs in all, giving a good range of voltage indication. The topmost LED, LED1, comes on for voltages above 14V which will occur when the battery is fully charged. LED2 indicates for voltages between 13.5V and 14V while LED3 indicates between 13V and 13.5V. Normally, one of these LEDs will be on. LED4 covers 12.5V to 13V while LED5 covers 12V to 12.5V. LED6 covers from 11.5V to 12V while LED7 comes on for voltages below 11.5V. These two LEDs are backed up by the piezo chime which beeps for voltages between 11.5V and 12V and becomes more insistent for voltages below 11.5V.

That might seem fairly conservative. After all, most cars will start with no troubles, even though the battery voltage might be a touch below 12V, won't they? Well, no. Some modern cars will happily crank the motor at voltages below 11V but their engine management will not let the motor start unless the voltage is above 11V. So don't think that a modern car will always start reliably. This little battery monitor could easily prevent a very inconvenient failure to start! So let's describe the rest of the circuit. The incoming supply is connected via diode D1 which provides protection against reverse polarity while zener diode ZD1 provides protection from spike voltages.

A standard 7805 3-terminal regulator is then used to provide a stable 5V to the microcontroller. The battery voltage is sensed via a voltage divider using 33kΩ and 100kΩ resistors. This brings the voltage down to within the 0-5V range for the A/D input of the PIC16F819. Port B (RB0 to RB7) of the microcontroller is then used to drive the various LEDs, with current limiting provided via the 330Ω resistor network. RB7, pin 13, drives a switching transistor for the piezo buzzer.

Software:

For the software, the design follows the basic template for a PIC microcontroller. Port A and its ADC (analog-to-digital converter) function are set up while port B functions as the output for the LEDs and buzzer. Once the set-up is complete, a reading will be taken at port RA2, the input for the A/D convertor. This reading is then compared with a series of values to determine the range of the voltage. This is similar to a series of "if" statements in Basic language. If the voltage is found to be within a certain range, the relevant port B pin will be turned on. If the voltage is below 12V, the buzzer will be turned on for a brief period, to signal a low battery condition. As the voltage falls below 11.5V, the frequency of the beeps will increase, to signal increased urgency.

Building it:

All the parts are mounted on a small PC board measuring 46 x 46mm (available from Futurlec). The starting point should be the IC socket for the PIC16F819, as this is easiest to mount while the board is bare. The next item can be the PC terminal block. The resistors and capacitors can then follow. Make sure the electrolytics are inserted with correct polarity.

Make sure that you do not confuse the zener (ZD1) with the diode when you are installing them; the diode is the larger package of the two.

Even more important, don't get the 78L05 3-terminal regulator and the 2N3906 transistor mixed up; they come in identical packages. The 78L05 will be labelled as such while the 2N3906 will be labelled "3906". And make sure you insert them the correct way around. The buzzer must also be installed with the correct polarity. The 330Ω current limiting resistors are all in a 10-pin in-line package. There are four green LEDs, two yellow and one red. They need to be installed in line and with the correct orientation.

Testing:

Before you insert the PIC16F819 microcontroller, do a voltage check. Connect a 12V source and check for the presence of 5V between pins 14 & 5 OF IC1. If 5V is not present, check the polarity of regulator REG1 and the polarity of the diode D1. If these tests are OK, insert the IC and test the unit over a range of voltage between 9V and 15V. Make sure that all LEDs come on in sequence and the piezo buzzer beeps for voltages below 12V.

Now it is matter of installing the unit in your car. It is preferable to install the unit in a visible position for the driver. However, it should not obscure any other instruments. The unit should be connected to the car's 12V supply after the ignition switch. This will turn the unit off with the other instruments and prevent battery drain while the motor is not running.

Author :Alan Bonnard

Readmore → A Car Battery Monitor Circuit Diagram

Sunday, 26 March 2017

Auto Sound Systems One Piece at a Time

Those who are in the market for auto sound systems are probably well aware of the many decisions that need to be made throughout the process. Gone are the days when you went in, pointed to a box and walked out with all the pieces, parts, and components you would ever need for a really kickin' sound. The truth of the matter is that there are many pieces and parts that work together in order to create the ultimate sound system and everyone seems to have different requirements, styles, tastes, and budgets to work with.

Because of this, many manufacturers of auto sound systems have wised up to the fact that some people will buy the components they need to create the sound system of their dreams piece by piece as budgets allow. This is actually a very intelligent way for customers on a budget to buy the sound system they are hoping to some day have. As a result you will find that speakers, amplifiers, sub woofers, and the actual stereo are often sold separately and at very reasonable prices.

Most of us hate living within limited budgets but understand that often in life it is a necessary evil. Living on a budget is not such a terrible thing really. If we had everything we wanted, what on earth would there be to look forward to? At least that is what I keep telling myself. I, however, seem to be the queen of budget living and bargain hunting. I love little more in life than finding a great deal on an item I've had my eye on for quite a while and hate little more than finding it cheaper once I've purchased it. As such, I tend to invest a great deal of time researching any major purchase before taking the plunge. A good auto sound system by this I mean good quality, minimal features is going to run (total package and installation) at least $1,000 with many costing a good deal more than that.

That doesn't mean you need to have a thousand bucks lying around the house in order to begin building your auto sound system. You can buy a decent set of speakers for around $200-$260 if you desire. You can find sets at lower prices, but this is the price for a fairly decent set of speakers that should serve you well. Keep in mind that you could very easily spend a lot more than this on speakers if you aren't careful. Living on a budget means you have to make some sacrifices along the way in order to have the things you want in life. Buy the speakers and have them installed (if you can do it or your know someone who can, this will save a lot of time and money).

Once you have the first component, whichever one that may be (that choice is entirely up to you and largely dependent on your personal tastes and which need replacing worse in the vehicle you own) you can begin saving towards the next. You should also consider asking friends and family (who would like to know what to get you for the holidays) to help you reach your smaller goals along the way. Most people are glad to help with specific items if they know what those items are. The point is that this isn't an all or nothing proposition. Take small steps towards your prize and you will find that you are constantly getting one step closer.

Readmore → Auto Sound Systems One Piece at a Time

Saturday, 25 March 2017

Triac Light Switch as a dimers

The series of light switches this time slightly different from the voltage of work. The series of light switches can work directly on the AC power network. Light switches are using the main component of TRIAC and LDR. The circuit is very simple and the components were sold in the market.

If you want a light reception sensitivity of this circuit can be arranged then the 3.3 MOhm resistor can be replaced with a variable resistor. For more details can be seen from the following series of images.

Circuit Diagram

With Triac Light Switch series is as dimers, but dimers control performed by the reception of light around the LDR. The lower the intensity cayaha received LDR then bright lights. For installation LDR need to be considered so as not exposed to light from the lamp directly.

Readmore → Triac Light Switch as a dimers

Build a Battery Circuit for Backup and Standby Operation

The circuit was designed to create a spare and reserve power source with the use of batteries during the absence of power from the mains.

BD139 – NPN power transistor used for driver stages in hi-fi amplifiers and television circuits because of its low voltage at 80 V maximum and high current at 1.5 A maximum.
Bridge Rectifier – also known as bridge rectifier which has four diodes arranged in a bridge configuration where the output voltage has the same polarity with either polarity of the input voltage.
1N4002 – a 1.0 Amp Silicon rectifier with voltage range of 50 to 1000 Volts and possessing features such as guaranteed high temperature soldering, high current capability, diffused junction, low reverse leakage, utilizes void-free molded plastic technique for low cost construction, and carries Underwriters Laboratory Flammability Classification of 94V-0 by its plastic package.

One of the main components in the construction of this circuit is the transformer which is rated with 230V/10V with a given current of 0.5A. It will handle the transfer of electrical energy from one circuit to another via inductive conductors or windings. Other components include a bridge rectifier and an electrolytic capacitor. This will be followed by an 8V2 Zener diode rated at 0.4W, which provides the regulation of voltage in the transistor as it is connected in series with the base to produce a constant output voltage of 7.5 V.

Battery Circuit for Backup and Standby Operation

To produce the desired 7.5 V, there are five batteries used in this circuit with 1.5 V each, in series with diode D7. This voltage is hanging across the output terminals, which takes over in case of failure in the main supply. The power supply will be reduced to 7 V due to the voltage drop across D7. The presence of resistor R3 performs an additional operation where it drops the charging of dry cells or storage battery, when it stops working with the main supply. To obtain the actual resistance of R3, the voltage potential difference between the battery and the Zener diode D6 is divided by the reliable current drop which measures around 0.7 mA.

The circuit of 7V backup battery is widely applied in several uninterruptible power supplies that efficiently function in times of power outage. Some models are incorporating the use of Lithium Ion and NiCd types of batteries. The most advantage feature that the circuit brings is providing backup power for emergency and important loads. Other models are created with high power capability to support high power applications.

Readmore → Build a Battery Circuit for Backup and Standby Operation

Thursday, 23 March 2017

12 Volt 2 A Switching Power Supply Circuit Diagram

This is a Simple 12 Volt / 2 A Switching Power Supply Circuit Diagram. The circuit 12 volt / 2 A switching power supply in the above scheme is not too complicated. At the output of this block provides a stable 12 V and maximum current 2A. Power supply units are quite compact and is suitable for debugging schemes, as well as a permanent resource for stationary devices, including power for the logic electronics for the home-made CNC machine tools.

Circuit Diagram

Transformer is available in the free market and avoids the hassle of having to self-winding. The diode bridge BR 1 of any given voltage and current of 2A. All other elements in the high part of the circuit are designed by the same voltage, taking into account the mains. The scheme of 12 volt / 2 A switching power supply operates from the high voltage network, to be observed when mounting accuracy and caution when using. It is desirable to block the finished board to “pack” in the body.

Readmore → 12 Volt 2 A Switching Power Supply Circuit Diagram

Thursday, 16 March 2017

Simple Project to Build A Video Signal Emphasis

With this circuit we can amplification selectively the high signal of picture frequencies [Video] with result bigger clarity than this. The circuit should be placed between a Video unit and the reception Scart or the plug Video input of television receiver. The designing is simple, it’s based in three only transistor.

Video Signal Emphasis Circuit Diagram

The first stage of Q1 function as isolator - adapter of input impedance. The second stage round the Q2 in common base connection which the gain is determined by the TR2. The TR1, R6 and C3 determine the frequency response. The third stage round the Q3 works as output buffer and 75-ohm line driver. The TR2 should be regulated in a place where the circuit output voltage, to be 1Vp-p, in 75 ohm load. The circuit functions with 12Volts - 50mA well stabilized.

Part List

R1=82ohm
R2=5.6Kohm
R3-9-11=2.7Kohm
R4=330ohm
R5=220ohm
R6=470ohm
R7=270ohm
R8=12Kohm
R10=2.2Kohm
R12=180ohm
R13=68ohm
C1-4-5=100uF 16V
C2=2200uF 16V
C3=470pF ceramic
C6=470uF 16V
C7=220uF 16V
C8=100nF 100V MKT
TR1=250ohm trimmer
TR2=500ohm trimmer
D1=1N4148
Q1-2-3=BC547
J1-2=Female RCA jack
J3=2pin connector 2.54mm step

Video Signal Emphasis PCB

Readmore → Simple Project to Build A Video Signal Emphasis

Wednesday, 15 March 2017

Square A to Sine Wave Converter Circuit Diagram

Build a Square A to Sine Wave Converter Circuit Diagram. This is a simple circuit diagram in this circuit using Two pairs of MOSFETs form a bridge that alternately switches current in opposite directions. Two parallel-resonant LC circuits complete the converter. The Ll/C1 combination is resonant at the fundamental frequency; the L2/C2 combination is resonant at the clock frequency`s third harmonic and acts as a trap.

Square A to Sine Wave Converter Circuit Diagram

Tl and C3 ensure that both halves of the MOSFET bridge are never on at the same time by providing a common delay to the gate drive of each half. Select the values of R1 and C3 to yield a time constant that`s less than 5% of the clock`s period. You can add an output amplifier for additional buffering and conditioning of the circuit`s sine-wave output.

Readmore → Square A to Sine Wave Converter Circuit Diagram

Monday, 6 March 2017

Make a Hi End RF Remote Control Circuit

Building a hi-end remote control device using very few components today looks pretty plausible. The proposed remote control light switch circuit idea provides you with the opportunity of building and owning this amazing device through simple instructions. Moreover the unit provides a 4-bit data to be exchanged between the transmitter and the receiver modules.
This Hi-tech remote control light switch enables you to control four individual lights or any electrical appliance for that matter from any corner of your house remotely using a single tiny remote control hand set. Build the “amazement” right on your workbench.
Imagine switching a light, a fan, washing machine, computer or similar gadgets from any corner of your room without taking a step! Doesn't that sound great? Controlling a particular gadget remotely through a single flick of your finger definitely feels very amusing and amazing too. It also gives you the comfort of doing an act without moving or getting up from a particular position.
The present circuit idea of a remote control light switch enables you controlling not only just a single light but four different electrical gadgets individually using a single remote control hand set.
Let’s try to understand its circuit functioning in details.

Circuit Description:

I have already discussed the wireless control modules through one of my previous articles, let’s summarize the entire description yet again and also learn how simply the stages may be configured into the proposed unit.
The first figure shows a standard transmitter module using the RF generator chip TWS-434 and the associated encoder chip the HOLTEK’s HT-12E.
The IC TWS-434 basically does the function of manufacturing and transmitting the carrier waves into the atmosphere.
However every carrier signal needs modulation for its proper execution, i.e. it needs to be embedded with a data that becomes the information for the receiving end.
This function is done through its complementing part – the HT-12E 4-bit encoder chip. It has got four inputs, which can be triggered discretely by giving them a ground pulse individually. Each of these inputs produces coding which are distinctly different to each other and become their unique signature definitions.
The encoded pulse from the relevant input is transferred to the IC TWS-434 which carries forward the data and modulates it with the generated carrier waves and finally transmits it into the atmosphere.
The above operations take care of the transmitter unit.

The receiver module does the above operations just in the opposite manner.
Here, the IC RWS-434 forms the receiving part of the module; its antenna anticipates the available encoded pulses from the atmosphere and captures them immediately as they are sensed.
The captured signals are relayed forward to the next stage – the signal decoder stage.
Just like the transmitter module, here too a complementing device the HOLTEK’s HT-12D is employed to revert the received encoded signals.
This decoding chip also consists of a 4-bit decoding circuitry and their outputs.
The received data is appropriately analyzed and decoded.
The decoded information gets terminated out through the relevant pin-out of the IC.
This output is in the form of a logic high pulse whose duration depends on the duration of the ground pulse applied to the encoder chip of the transmitter module.
The above output is fed to a Flip-Flop circuit using the IC 4017, whose output is finally used to switch the output load via a relay driver circuitry.
One such flip/flop idea is shown you may construct four of them to access each of the generated 4-bit data discretely and control four gadgets individually.

Whether you use it as a remote control light switch or to control many more appliances……the option is all yours.

Readmore → Make a Hi End RF Remote Control Circuit

Sunday, 5 March 2017

Fixing the pots on a Maxon OD808

I was recently gifted the pedal pictured above. If you don’t know what a Maxon OD808 is, then you should have a look here: http://www.musiciansfriend.com/distortion-overdrive-effects-pedals/maxon-od808-guitar-overdrive-pedal

From the above link: “Originally released in 1979, the Maxon OD808 pedal was one of the first tube-amp overdrive simulators to hit the market. Its smooth, creamy crunch tone caught on quickly, and helped to launch a long line of imitators. Today, the OD808 design is without a doubt the most used, most imitated and most lauded overdrive circuit of all time. The reason for this is simple--tone. Simply put, the OD808 provides the natural, mild overdrive of a tube amp without sacrificing your guitar's original tone. In addition, it can be used as a clean booster to provide increased gain without compromising the sound of your amplifier.”

In short, it’s basically the original overdrive pedal that eventually got rebranded as the Ibanez Tubescreamer.

Unfortunately this particular one had a few issues. At first it looked like it was just missing a knob, but it turned out that all three pots were able to rotate freely (through 360 degrees) without affecting the sound at all. The pot shafts could also move in and out by about 6 mm, which really shouldn’t be the case.

So I took the back cover off to access the circuit board.

Removing the two screws at the bottom end of the board revealed a second board that houses the pots and status LED.

Removing that revealed exactly what I was expecting, which was that all three pots had fallen apart (evidently someone has tried to hold one together at some time in the past with a cable tie).

In fact you can see the top parts of the pots still attached to the enclosure:

Sadly this pedal has made a bit of a (bad) name for itself because of this exact issue. Not only are the pots prone to mechanical failure in this way, but it is also quite hard to find exact replacements, which in case anyone ever needs this information are as follows:

Overdrive: A500K (ALPS brand, part number RK09L1140-F12-C0-A504)
Tone: A20K (ALPS brand, part number RK09L1140-F12-C0-A203)
Balance: B100K (ALPS brand, part number RK09L1140-F12-C0-B104)

And here's the specs document for these ALPS pots for those that may want it: http://docs-europe.electrocomponents.com/webdocs/0f4c/0900766b80f4c570.pdf

Having had little initial luck locating replacements, I decided to see if I could just put the pots back together. This was surprisingly easy to do and the fix feels pretty strong.

This worked for the Overdrive and Balance pots, but unfortunately the Tone one was still very spotty, even with a squirt of contact cleaner.

So this time I decided to completely remove and disassemble that pot. It breaks down into several parts, but on the plus side, it's surprisingly serviceable.

From top to bottom you can see the securing nut, the shaft collar, the shaft, the carbon strip/legs, the wiper, the back cover and the securing clip (which both holds the enclosure together and also secures it to the board).

So first I gave the carbon strip a good clean with contact cleaner and a cloth:

Then checked the wiper to make sure it was in shape and clean.

Then started putting the whole thing back together.

First the wiper is placed against the carbon strip, making sure that it is in a suitable position (i.e. not outside if its usual rotation range—I put it in what would be its middle position):

Then the back cover is replaced:

Now the shaft is located so that it sits correctly in the wiper part (the shaft has a little key so that it will only sit correctly in one position).

The collar is slid over the shaft and pushed solidly against the rest of the pot.

Before putting the clip back on, I slowly and carefully bent the ends so that they were close to straight:

And then bent the whole legs so that they were a little tighter than parallel.

This was so that they wouldn’t have a tendency to open after putting the pot all back together.

Finally, the ends were pressed back into a 90 degree angle:

The pot was tested and passed with flying colours:

And re-soldered to the board:

Finally the whole thing was put back together and correct replacement knobs were put on too.

I tried it out (it works fine) and have to say this pedal sounds great and is definitely a keeper.

Readmore → Fixing the pots on a Maxon OD808

A Bedside Lamp Timer Circuit Diagram

Description

The purpose of this circuit is to power a lamp or other appliance for a given time (30 minutes in this case), and then to turn it off. It is useful when reading at bed by night, turning off the bedside lamp automatically in case the reader falls asleep... After turn-on by P1 pushbutton, the LED illuminates for around 25 minutes, but then it starts to blink for two minutes, stops blinking for two minutes and blinks for another two just before switching the lamp off, thus signaling that the on-time is ending. If the user want to prolong the reading, he/she can earn another half-hour of light by pushing on P1. Turning-off the lamp at user's ease is obtained by pushing on P2.

Circuit diagram:

Parts:

R1 = 1K
R2 = 4K7
R3 = 10M
R4 = 1M
R5 = 10K
C1 = 470µF-25V
C2-C4100nF-63V
C1 = 470µF-25V
C2-C4 = 100nF-63V
D1-D4 = 1N4002
D5 = 5mm. Red LED
IC1 = CD4012
IC2 = CD4060
Q1 = BC328
Q2 = BC547
P1,P2 = SPST Pushbuttons
T1 = 9+9 Volt Secondary 1VA Mains transformer
RL1 = 10.5V 470 Ohm Relay with SPDT 2A 220V switch
PL1 = Male Mains plug
SK1 = Female Mains socket

Circuit operation:

Q1 and Q2 form an ALL-ON ALL-OFF circuit that in the off state draws no significant current. P1 starts the circuit, the relay is turned on and the two ICs are powered. The lamp is powered by the relay switch, and IC2 is reset with a positive voltage at pin 12. IC2 starts oscillating at a frequency set by R4 and C4. With the values shown, pin 3 goes high after around 30 minutes, turning off the circuit via C3. During the c6 minutes preceding turn-off.

The LED does a blinking action by connections of IC1 to pins 1, 2 & 15 of IC2. Blinking frequency is provided by IC2 oscillator at pin 9. The two gates of IC1 are wired in parallel to source more current. If required, a piezo sounder can be connected to pins 1 & 14 of IC1. Obviously, timings can be varied changing C4 and/or R4 values.

Source - http://www.extremecircuits.net/2009/12/bedside-lamp-timer-circuit-schematic.html

Readmore → A Bedside Lamp Timer Circuit Diagram

Saturday, 4 March 2017

DRIVING A BI COLOURED LED USING NE555

Readmore → DRIVING A BI COLOURED LED USING NE555

Thursday, 23 February 2017

Top 5 Reasons for a New Auto Sound System

If you are a fan of David Letterman, I'm sure you've seen and heard his nutty and often hilarious top 10 lists. He has become famous for them and they have been often imitated but never quite aptly duplicated by many around the world. I have no intentions of trying to claim or ever hope to be as funny as Letterman but I would love to create a top 5 list of why you need a new auto sound system. The sad part is that some of this may ring true for many, if not, I bet it will at least make you smile.

5) You really hate your neighbors and secretly hope that enough loud, late night thumping from your car will convince them to move. Admittedly not the kindest reason for the need of a new auto sound system but if you've had some of my previous neighbors I am fairly certain that it isn't too bad of an idea. Just be careful not to shake too much or they may be leaving part of their automobiles behind.

4) Because you saw it on Ebay and like Weird Al Yankovich you just can't seem to refuse when it comes to last minute bargains in the world's largest garage sale. The truth of the matter is that Ebay can be an excellent resource as far as auto sound systems go. It is important however, to remember that you really need to hear the system before you spend your hard earned money buying it and a lot of time and/or money on the installation of the sound system you select. For that reason Ebay may not be the best choice for your particular needs.

3) Because you're tired of crummy speakers that seem to play static more than music and make more popping and snapping sounds than your old fashioned popcorn popper. Speakers are often only a small part of how your sound system runs. Chances are if you are currently having speaker problems an entirely new auto sound system is going to be in order to insure that all the problems are fixed and solved to your complete satisfaction.

2) Because your Aunt Ethel who has cataracts has a better auto sound system than you. Believe me I know this one stings a little, especially when it hits home. We all hate to think that someone that is older has a more technologically hip and sound product than we do. We often like to kid ourselves into thinking that we live on the cutting edge of technology when that is probably far from the case. Aunt Ethel probably has the kicking sound system she does so that it can be heard without the assistance of miracle ear so keep that in mind before you pull all of your hair out.

And the number 1 reason you should get a new auto sound system is that the 8-trac went out of fashion long before your first child was born. Even though you've clung to the past, it has finally met its limitations of usefulness and it is time to move along and embrace the wonderful world of modern technology and what it can mean to you and the time you and your family spend riding in your vehicle. Hope you had a great smile for the day!

Readmore → Top 5 Reasons for a New Auto Sound System

Monday, 20 February 2017

Class A Headphone Amplifier

This circuit is derived from the Portable Headphone Amplifier featuring an NPN/PNP compound pair emitter follower output stage. An improved output driving capability is gained by making this a push-pull Class-A arrangement. Output power can reach 427mW RMS into a 32 Ohm load at a fixed standing current of 100mA. The single voltage gain stage allows the easy implementation of a shunt-feedback circuitry giving excellent frequency stability.

Class-A Headphone Amplifier Circuit diagram

The above mentioned shunt-feedback configuration also allows the easy addition of frequency dependent networks in order to obtain an useful, unobtrusive, switchable Tilt control (optional). When SW1 is set in the first position a gentle, shelving bass lift and treble cut is obtained. The central position of SW1 allows a flat frequency response, whereas the third position of this switch enables a shelving treble lift and bass cut.

Note:

Before setting quiescent current rotate the volume control P1 to the minimum, Trimmer R6 to zero resistance and Trimmer R3 to about the middle of its travel.
Connect a suitable headphone set or, better, a 33 Ohm 1/2W resistor to the amplifier output.
Connect a Multimeter, set to measure about 10Vdc fsd, across the positive end of C5 and the negative ground.
Switch on the supply and rotate R3 in order to read about 7.7-7.8V on the Multimeter display.
Switch off the supply, disconnect the Multimeter and reconnect it, set to measure at least 200mA fsd, in series to the positive supply of the amplifier.
Switch on the supply and rotate R6 slowly until a reading of about 100mA is displayed.
Check again the voltage at the positive end of C5 and readjust R3 if necessary.
Wait about 15 minutes, watch if the current is varying and readjust if necessary.

Parts List :

P1 : 22K Dual gang Log Potentiometer 
R1 : 15K 
R2 : 220K
R3 : 100K
R4 : 33K 
R5 : 68K 
R6 : 50K 
R7 : 10K 
R8,R9 : 47K 
R10,R11 : 2R2 
R12 : 4K7
R13 : 4R7
R14 : 1K2
R15,R18 : 330K
R16 : 680K
R17,R19 : 220K
R20,R21 : 22K
C1,C2,C3,C4 : 10µF/25V 
C5,C7 : 220µF/25V
C6,C11 : 100nF
C8 : 2200µF/25V
C9,C12 : 1nF
C10 : 470pF
C13 : 15nF
D1 : LED
D2,D3 : 1N4002 
Q1,Q2 : BC550C 
Q3 : BC560C 
Q4 : BD136 
Q5 : BD135 
IC1 : 7815
T1 : 15CT/5VA Mains transformer
SW1 : 4 poles 3 ways rotary Switch 
SW2 : SPST slide or toggle Switch

Readmore → Class A Headphone Amplifier

Thursday, 16 February 2017

Converting a DCM Motor

We recently bought a train set made by a renowned company and just couldn’t resist looking inside the locomotive. Although it did have an electronic decoder, the DCM motor was already available 35 (!) years ago. It is most likely that this motor is used due to financial constraints, because Märklin (as you probably guessed) also has a modern 5-pole motor as part of its range. Incidentally, they have recently introduced a brushless model.

The DCM motor used in our locomotive is still an old-fashioned 3-pole series motor with an electromagnet to provide motive power. The new 5-pole motor has a permanent magnet. We therefore wondered if we couldn’t improve the driving characteristics if we powered the field winding separately, using a bridge rectifier and a 27 Ω current limiting resistor. This would effectively create a permanent magnet. The result was that the driving characteristics improved at lower speeds, but the initial acceleration remained the same. But a constant 0.5 A flows through the winding, which seems wasteful of the (limited) track power. A small circuit can reduce this current to less than half, making this technique more acceptable.

Circuit diagram :

Converting a DCM Motor Circuit Diagram

The field winding has to be disconnected from the rest (3 wires). A freewheeling diode (D1, Schottky) is then connected across the whole winding. The centre tap of the winding is no longer used. When FET T1 turns on, the current through the winding increases from zero until it reaches about 0.5 A. At this current the voltage drop across R4-R7 becomes greater than the reference voltage across D2 and the opamp will turn off the FET. The current through the winding continues flowing via D1, gradually reducing in strength. When the current has fallen about 10% (due to hysteresis caused by R3), IC1 will turn on T1 again. The cur-rent will increase again to 0.5 A and the FET is turned off again. This goes on continuously.

The current through the field winding is fairly constant, creating a good imitation of a permanent magnet. The nice thing about this circuit is that the total current consumption is only about 0.2 A, whereas the current flow through the winding is a continuous 0.5 A.

We made this modification because we wanted to convert the locomotive for use with a DCC decoder. A new controller is needed in any case, because the polarity on the rotor winding has to be reversed to change its direction of rotation. In the original motor this was done by using the other half of the winding.

There is also a good non-electrical alter-native: put a permanent magnet in the motor. But we didn’t have a suitable magnet, whereas all electronic parts could be picked straight from the spares box.

Author : Karel Walraven

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Friday, 10 February 2017

A Simple Detector with Amplification

A simple shortwave radio detector is neither very sensitive nor very selective. However, with a little extra amplification we can improve the reception performance significantly.

The additional circuit is designed to compensate for the losses in the resonant circuit. A transistor is used to amplify the RF signal and feed it back into the resonant circuit. When the gain is set correctly we can make the amount of this feedback exactly equal to the losses. The resonant circuit is then critically damped and has a very high Qfactor. Now we can separate transmissions that are just 10 kHz apart, and we can tune in to very weak stations.

Detector with Amplification Circuit Diagram :

The tuning capacitor used has two gangs of vanes with capacitances of 240 pF and 80 pF. These two gangs are connected in parallel to make a 320 pF variable capacitance. The air-cored inductor has 25 turns on a diameter of 10 mm, with taps at 5-turn intervals. The resonant circuit so formed is capable of covering the full shortwave band from 5 MHz to 25 MHz.

The short wave detector can be connected to a power amplifier, or, for exam-ple, amplified PC loudspeakers. The antenna does not have to be very long: in experiments we used a one metre length of wire. Tuning the radio involves adjusting the variable capacitor to bring in the station and then adjusting the gain of the feed-back circuit for optimal output volume. If the potentiometer is turned up too far, the receiver will go into self-oscillation and become a mini-transmitter. At the optimal setting the sound quality is very pleasant and certainly no worse than many ordinary shortwave radios.

If you find shortwave detectors that use a battery and an amplifier a little new-fangled, you can get your fix of nostalgia by dispensing with the battery and connecting a crystal earpiece to the detector’s output. The radio will of course also work without the feedback circuit, but with rather poorer performance.

Author :Burkhard Kainka - Copyright : Elektor

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Wednesday, 1 February 2017

200W K1058 J162 MOSFET Class A Audio Amplifier Circuit

J162 K1058 MOSFET amplifier circuit. Welcome to Free dot com circuit we want audio amplifier circuit, as amp is currently composed of two completely separate mono amplifiers for each channel has its own power supply, inter-channel crosstalk zero, a common phenomenon in amplifiers, the same the diet. 40VAC at 640VA to evaluate the performance of a transformer in order to obtain full 40VAC – 0 -.

Unlike many designs that deliver on the capacitors, the current peaks, I prefer the raw power available from the transformer are in rapid transients.

K1058 J162 200 Watts MOSFET amplifier circuit class-A. Although RAS-300 specifications moderate when they hear, immediately causing the huge reserves of power available and not out of fear that something would result in a very strong during the conduct of the amplifier.

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Monday, 30 January 2017

Make A Virtual Phone Battery

Virtual cell phone battery is a replacement cell phone batteries for those of you who use the phone as a modem. Including myself, who use the phone as a modem HAIER d1200p internet. Why must use this virtual battery. For those who surf hobby "full time" with a phone modem, would know the problem, the battery gets hot and fast reply wasteful even worn out.

This tool is a good solution to keep and care for our cell phones from the possibility of damage from over-charging its battery.I created a virtual battery works as follows:We take the source of its power supply from the USB port because the port is very easy and simple to use and simply provide a standard current source when the phone is online (500-750mA).

The workings of the circuit is as follows:Diodes or diode 2Amper in 5239 this standard to provide a useful addition to the polarity of the voltage which is also a component of protection against misuse. You can just use a 1 Amp diode (IN4002-4007). I use the IN 5239 is due to be durable, more resistant to heat.4v3 zener diode IN4007 and configured to create a portal voltage of 5V (4.3 + 0.7 volt zener Vin4007) and is useful as a protection system against possible voltage spikes in the event of damage to the CPU.220nF capacitor as a stabilizer and a substitute for the original battery cells.

The following also 100pF capacitor to smooth and filter the dc current through the diode 5239 which came out of the induction logging.Configuration between zener4v3, IN4007 diode and C 220n form a cell replacement from the actual battery cells, because the battery was actually a capacitor which had a large capacity.You can just remove the three components mentioned above. although it can work fine .

But results are not as good as that use virtual cell (replacement), which certainly was the security which we have to think to avoid the things which are not in want.Making way is to use an old cell phone batteries which have been wasting his cell, a raft of this circuit and the solder terminals on the batteries with the polarity distinguished. Make two holes for the cable to the jack / USB jack.

Determine the length of cable required to taste and use stranded cable with a diameter of at least 1mm.If some type of cell phone batteries are very thin, use a small box for this circuit and connect the two wires to the output voltage again for hp battery casing. Or also if you do not have a former battery casing, use alligator clips to the battery terminal on the phone .. Pin the middle of the virtual pin replacement battery is BSI (Battery Size Insdicator) is useful for HP Nokia.

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Tuesday, 24 January 2017

A Good Auto Sound System is a Requirement not a Luxury

How do you decide which auto sound system is best for you? This is a question that many consumers ask in the U. S. each and every day. The truth is that only you can decide what kind of sound you find enjoyable and what you are seeking in the sound system you will ultimately purchase. A good sound system will greatly improve how you feel about not only the vehicle you drive but also your disposition after your daily commute. It may seem like such a small thing, the changing of a sound system, but it does seem to have such a profound impact on how we start our days. Of course we all know that getting your day off to a good start sets the tone for the entire day and if that day is Monday it sets the tone for not only the day ahead but also the week to come.

Music affects almost every aspect of our lives. Most of us do not realize the impact that music has on our day-to-day lives and it is quite difficult because our world seems to be filled with it. It is much easier however, to explain the difference a good sound system makes. It's funny, I find myself in a hurry to get out of stores that have lousy sound systems and speakers that dribble out little more than static while I can shop for hours in a store that has tasteful music playing in the background over a good sound system. I prefer the volume lower and the music playing in the background rather than being the center of my attention.

Most of us find that soft music playing in the background is rather unobtrusive and allows us to get along with our thoughts and the mission at hand while loud music blaring over antiquated speakers does a great deal to disrupt our thought processes which will only serve to send us along to the next errand on our list. If you'll notice it seems that clerks in the stores where the loud music blares along are often not as even tempered as those in stores that play music at respectful volumes and have very well kept sound systems. I think I would be cranky too after listening to music in a manner that music wasn't meant to be heard.

I'm not a music snob by any means; I simply enjoy listening to music for the sake of actually hearing the music. Loud music is good sometimes but not when I have other things on my mind. I prefer that music remain in the background when I'm running about taking care of errands, even in the car. The hallmark of a good auto sound system is that it sounds good even at low volumes. This means you can enjoy music in the background, hum along, or simply ignore the music in favor of the action taking place on the road.

The point I'm trying to make is that even though you may not realize the impact that a good auto sound system has on music immediately, you will definitely feel the difference it makes over time. The better the sound system, the better the sound and music is after all, sound.

If you are a true lover of music and spend a great deal of your week or even any given day in your vehicle, doesn't it make sense to invest heavily in your auto sound system? I know for me that particular decision is a no brainer. I love music and it is an important part of not only my life but also the lives of my children. As a result we spend a lot of time listening to the radio in our SUV and singing along. Even when we aren't listening to music, I enjoy listening talk radio and the news on NPR. These things are an important part of my day and I really enjoy all that each and every one adds to my life. Because of that, I find my investment in a good auto sound system to be a requirement rather than a luxury.

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Sunday, 22 January 2017

zBot 10 A Power Stage for DC Motor Circuit Diagram

zBot :10-A Power Stage for DC Motor Circuit Diagram . If you look at the chassis of the zBot vehicle1, you’ll find two parts requiring intelligent control: the steering servo and the DC motor. The so called H-bridge is the normal circuit for electronic control of revolution speed and direction. The DC motor of a Tamiya car is powerful enough to propel zBot at up to 20 miles per hour.
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The motor then consumes more than 10 A, so we choose high-current power MOSFETs for the driver stage. There are lots of different devices to choose from. The MOSFET we require has to supply the maximum motor current and, importantly, it has to be switched with gate voltages of about 5 V. In this case, the microcontroller switches the power stage (‘low side’) directly. For high side driving level shifters are necessary. The schematic of the H-bridge power stage shows a few inverters, NAND gates and two tri-stateable drivers. These logic functions are very important as the easier way, i.e.., directly controlling all four MOSFET has a fatal disadvantage.

zBot :10-A Power Stage for DC Motor Circuit Diagram

In case of a software crash it could happen that two ore more MOSFETs are switched on incor-rectly for exam-ple, T4 and T7. In that case, the current through the transistors is limited by the internal resistors of the MOSFETs (about 10 mO) only. Such a fatal error would destroy the MOSFETs. The logic functions configured here effectively avoid illegal states.To control the DC motor, three signals are needed: DIR, PWM and STOP. DIR controls the direction of the motor revolution, PWM the speed, and STOP brakes the motor.

The software module for the DC motor is called dcm.c.(070172-I) The complete document called Zbot the Robot Experimental Platform is available for free downloading from the Elektor Electronics website. The file number is 070172-11.zip (July/August 2007).

Sourced by : Circuitsstream.blogspot.com

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How to make a guitar cable

Today we're going to do a quick run through of how to make a guitar cable. It’s a pretty simple procedure, but if you’ve never made one before, it can be a little bit daunting at first.

To make a cable, you will need to following items:

Some cable
Two ¼” jack plugs

And the following tools:

A soldering iron and some solder
Wire cutters/strippers/pliers

Here’s the cable we're going to use:

And we're going to use two of these jack plugs:

I really like this design of plug (and I’ve used a tonne of different ones over the years). To open it, you unscrew the end cap/cable relief:

Then lift up the cover:

Which reveals the following:

Obviously you can use a different design if you like.

Today we're making a short cable that will go between effects pedals. There’s nothing different between this sort of cable and a standard guitar cable, apart from the length.

This one, we're going to cut to 20cm (8”):

Then trim the outer sleeve back by 15mm (a little under 5/8”):

We trim the inner wire insulation back by a few mm and then twist the end of the wire together. The outer shielding wiring is also gathered and twisted together:

All of this is done at both ends, leaving us with this:

We then slide any necessary items over the cable before doing any soldering. You’ll get away with forgetting this for the first plug, since you can always slide it on from the other end after soldering. However, for the second plug, it’ll be too late and you’ll have to unsolder something to fix it.

Next step is to melt a couple of healthy blobs of solder onto the two positions where we intend to attach wires.

Then we “tin” the wires, which is to say, we melt a little bit of solder onto them:

We're also going to cut the outer ground wire a little shorter, so that it fits its position on the plug better:

Now we solder the wires on. When doing this, try not to keep the soldering iron on the plug for an extended amount of time, as some of them can be ruined very easily.

Firstly, the ground wire: