Secret Diagram: Build

Showing posts with label Build. Show all posts

Saturday, 25 March 2017

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.

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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

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Wednesday, 8 March 2017

How to build Digital Step Km Counter Circuit Schematic

Description

This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants' pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km. and its dot is always on to separate Km. from hm. The rightmost display D1 (the least significant digit) shows hundreds meters and its dot illuminates after every 50 meters of walking.

A beeper (excludable), signals each count unit, occurring every two steps. A normal step was calculated to span around 78 centimeters, thus the LED signaling 50 meters illuminates after 64 steps (or 32 operations of the mercury switch), the display indicates 100 meters after 128 steps and so on.

For low battery consumption the display illuminates only on request, pushing on P2. Accidental reset of the counters is avoided because to reset the circuit both pushbuttons must be operated together. Obviously, this is not a precision meter, but its approximation degree was found good for this kind of device. In any case, the most critical thing to do is the correct placement of the mercury switch inside of the box and the setting of its sloping degree.

Circuit diagram:

Parts:

R1 = 22K 1/4W Resistor
R2 = 2.2M 1/4W Resistor
R3 = 22K 1/4W Resistor
R4 = 1M 1/4W Resistor
R5 = 4.7K 1/4W Resistor
R6 = 47R 1/4W Resistor
R7 = 4.7K 1/4W Resistor
R8 = 4.7K 1/4W Resistor
R9 = 1K 1/4W Resistor
C1 = 47nF 63V Polyester Capacitor
C2 = 100nF 63V Polyester Capacitor
C3 = 10nF 63V Polyester Capacitor
C4 = 10µF 25V Electrolytic Capacitor
D1 = Common-cathode 7-segment LED mini-display (Hundreds meters)
D2 = Common-cathode 7-segment LED mini-display (Kilometers)
Q1 = BC327 45V 800mA PNP Transistors
Q2 = BC327 45V 800mA PNP Transistors
P1 = SPST Pushbutton (Reset)
P2 = SPST Pushbutton (Display)
IC1 = 4093 Quad 2 input Schmitt NAND Gate IC
IC2 = 4024 7 stage ripple counter IC
IC3 = 4026 Decade counter with decoded 7-segment display outputs IC
IC4 = 4026 Decade counter with decoded 7-segment display outputs IC
SW1 = SPST Mercury Switch, called also Tilt Switch
SW2 = SPST Slider Switch (Sound on-off)
SW3 = SPST Slider Switch (Power on-off)
BZ = Piezo sounder
B1 = 3V Battery (2 AA 1.5V Cells in series)

Circuit operation:

IC 1A & IC 1B form a monostable multi vibrator providing some degree of freedom from excessive bouncing of the mercury switch. Therefore a clean square pulse enters IC2 that divides by 64. Q2 drives the LED dot-segment of D1 every 32 pulses counted by IC2. Either IC3 & IC4 divide by 10 and drive the displays. P1 resets the counters and P2 enables the displays. IC1C generates an audio frequency square wave that is enabled for a short time at each monostable count. Q1 drives the piezo sounder and SW2 allows disabling the beep.

Notes:

Experiment with placement and sloping degree of mercury switch inside the box: this is very critical.
Try to obtain a pulse every two walking steps. Listening to the beeper is extremely useful during setup.
Trim R6 value to change beeper sound power.
Push P1 and P2 to reset.
This circuit is primarily intended for walking purposes. For jogging, further great care must be used with mercury switch placement to avoid undesired counts.
When the display is disabled current consumption is negligible, therefore SW3 can be omitted.

Source http://www.extremecircuits.net/2009/12/digital-step-km-counter-circuit.htm

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Friday, 17 February 2017

Build Electronic Project for Home Made Movie Maker

Like real movies, this circuit makes use of a characteristic of the human eye and brain known as the persistence of vision. A sequence of still pictures is projected onto a screen in rapid succession. The pictures differ slightly from one another and the brain interprets the succession of still pictures as continuous motion.
Here the pictures are shadows cast by low-voltage lamps. There are four Lamps in all, which glow in sequence cyclically. This gives the illusion of a simple but realistic movie.

Fig. 1 shows the circuit for the movie maker. It is driven by clock pulses provided by NAND gates N1 and N2. The flickering frequency is adjustable through preset VR1. A suitable rate for perceiving continuous motion is 16 Hz. The clock pulses are fed to counter IC CD4022 (IC2). IC2 has eight outputs, but only the first four (0-3) are used in this circuit. The outputs go high one at a time, in sequence. The fifth output (output 4) is connected to the reset input so that the counter is immediately reset at the fifth count and the first output (output 0) goes high.

The counter outputs are fed to CD4049 hex buffer (IC3). The buffer outputs drive transistors T1 through T4 in a sequence. As each transistor conducts, the lamp connected to it glows. The lamps are rated at 0.3A so these provide enough light to operate the movie show in a dimly-lit room.

Fig. 1: Circuit for movie maker:

Assemble the circuit on a general-purpose PCB. Power-on the circuitusing switch S1 and make sure that the outputs of IC2 (0 through 3) are normally low but briefly go high three-four times within a second. Also ensure that the lamps flash one at a time in a repeating sequence. If the sequence appears to be wrong or any of the lamps fails to glow, check the wiring. The light shield and film holder can be made of a thin card, sheet metal or plywood. Strictly adhere to the various dimensions as shown in Fig. 2. Otherwise, the shadow images may fail to register properly when projected.

Use a plastic cabinet as shown in Fig. 3 to hold the circuit board and battery. Owing to the power requirements of the lamps, it is more economical to use four 1.5V cells in a battery box. Else, you can use a 6V power adaptor.

Fig. 2: Assembly arrangement:

There are two ways of mounting the lamps. The more satisfactory but more expensive method is to bolt the four lamps. Alternatively, drill four 1cm dia. holes on the front of the cabinet, wedge the base of the lamps in these holes and solder wire to the bases.

Fig. 3: Plastic case with assembled circuit:

The easiest way to prepare the film frames is to photocopy the desired drawings onto transparent films. Alternatively, trace them on a transparent acetate film or draughtsman's film, using a fine marker pen. Align all the drawings on the frames and project onto the screen.

Fig. 3: Flim making:

Working of the circuit is simple. First of all, fix the clock frequency at about 16 Hz. Place the film on the holder. Ensure a distance of 12 cm between the screen and the assembled unit and power-on the circuit using switch S1. Now you can see your drawings as a short movie clip on the screen.

EFY note. We have tested this circuit without the mechanical arrangement.

Source: EFY

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Sunday, 15 January 2017

Build a Simple Home Alarm Circuit Using 555 ICs

This is a Simple Home Alarm Circuit Using 555 IC's. This circuit can be simplified by using a single 74C14 IC. This IC is also known by the following numbers: 40106, 40014, and 74HC14. These are CMOS chips and are characterised by low current consumption, high input impedance and a supply voltage from 5v to 15v. (Do not substitute 7414 or 74LS14. They are TTL chips and operate on 4.5v to 5.5v and have low impedance inputs.)

Simple Home Alarm Circuit Diagram

The 74C14 contains 6 Schmitt Trigger gates and 4 of these gates (Schmitt Inverters) are used in this circuit.
The circuit consists of a number of "building blocks" and the first consists of two transistors in a very clever "bootstrap" arrangement. The first transistor is turned on via the 3M3 and 47k. The second transistor is not turned on and the output is HIGH.

A small signal from the electret microphone will consist of positive and negative excursions and the negative excursion will turn the first transistor OFF. This will turn the second transistor ON and the left lead of the 100n will be pulled towards the 0v rail. The 100n is uncharged and the right lead will also be pulled towards the 0v rail and the input of the 74C14 will see a LOW. This will make the output HIGH and turn on the BC547 transistor.

When the second transistor turns ON, it also pulls the 2u2 down and this removes the "turn-on" voltage to the first transistor. The two transistors remain in this state for a few seconds while the 2u2 discharges and the voltage on the base of the first transistor rises. When this happens, the two transistors change state and the 2u2 charges. When the circuit is waiting to detect audio, the 2u2 is charged via the 47k on the base of the first transistor and 47k collector resistor of the second transistor (plus the base-emitter voltage drop of the first transistor).

Simple Home Alarm Circuit Diagram A

To exit the property, the EXIT button is pressed and this puts a HIGH on pin 1 of the IC so that any signal from the electret mic is not passed to the siren. The EXIT delay is determined by the value of the 100u and 2M2. Normally-open and normally-closed switches will also send a LOW to trigger the siren.

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Thursday, 5 January 2017

Build a Scanner Voice Squelch Circuit Diagram

This Scanner Voice Squelch Circuit Diagram detects the presence of audio (voice) on the output of a scanner. If the scanner stops on a `dead carrier` or noise, the circuit mutes the speaker to avoid annoying noise. Ul amplifies speech and drives rectifier D1/D2 and switch Ql. Comparator U3 drives speaker switch Ql and indicator LED1. Q2 completes the speaker path to ground. U2 is an audio amplifier to drive the speaker. R3 is a volume control. PL1 connects to the scanner speaker or to the headphone jack .

Build a Scanner Voice Squelch Circuit Diagram

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Tuesday, 6 December 2016

Build a LED Matrix Horizontally Circuit Diagram

LED Matrix Horizontally The circuit in this Design Idea shows an unconventional way to use a 5×7 LED matrix.You can use a design containing a set of 5×7 LED units without changing anything in the circuitry, except for the arrangement of the LED units.

LED Matrix Horizontally Circuit Diagram

Using one 5×7 LED matrix, or N units, horizontally instead of vertically allows the display of two characters, or 2×N characters. The minimum pattern for lowercase and uppercase letters requires only a 3×5 LED configuration, except for the letters M and m, which require at least a 5×5 LED configuration and need a dedicated subroutine.

The circuit in Figure 1 uses an 8-bit, 18-pin PIC microcontroller and a decade counter to drive one or two 5×7 LED units to provide a display module of two or four digits. The circuit uses a small pushbutton switch to increment the counter. By default, the circuit works in high-brightness mode. If you press the pushbutton during power-on, the circuit works in low-power mode.

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Sunday, 4 December 2016

Build a 10 Amp 13 8 Volt Power Supply Circuit Diagram

Sometimes amateurs like to home-brew their power supplies instead of purchasing one off the shelf at any of the major ham radio retail dealers. The advantage to rolling your own power supply is that it teaches us how they work and makes it easier to troubleshoot and repair other power supply units in the shack. It should be noted that there is no real cost advantage to building your own power supply unless you can get a large power transformer and heat sink for a super low price.

Of course rolling our own gives us the ability to customize the circuit and make it even more reliable than commercial units. The circuit in Figure 1 will give us 10 amps (12 amps surge) with performance that equals or exceeds any commercial unit. The circuit even has a current limiting feature which is a more reliable system than most commercial units have. Just like other commercial units, this circuit uses the LM723 IC which gives us excellent voltage regulation. The circuit uses 3 pass transistors which must be heat sinked. Resistor R9 allows the fine tuning of the voltage to exactly 13.8 volts and the resistor network formed by resistors R4 through R7 controls the current limiting.

The LM723 limits the current when the voltage drop across R5 approaches .7 volts. To reduce costs, most commercial units rely on the HFE of the pass transistors to determine the current limiting. The fault in that system is that the HFE of the pass transistors actually increases when the transistors heat up and risks a thermal runaway condition causing a possible failure of the pass transistors. Because this circuit samples the collector current of the pass transistors, thermal runaway is not a problem in this circuit making it a much more reliable power supply.

The only adjustment required is setting R9 to the desired output voltage of anywhere between 10 and 14 volts. You may use a front panel mounted 1K potentiometer for this purpose if desired. Resistor R1 only enhances temperature stability and can be eliminated if desired by connecting pins 5 and 6 of IC-1 together. Although it really isn’t needed due to the type of current limiting circuit used, over voltage protection can be added to the circuit by connecting the circuit of Figure 2 to Vout. The only way over voltage could occur is if transistors Q2 or Q3 were to fail with a collector to emitter short. Although collector to emitter shorts do happen, it is more much more likely that the transistors will open up when they fail.

10 Amp 13.8 Volt Power Supply Circuit Diagram

I actually tested this and purposely destroyed several 2N3055’s by shorting the emitters to ground. In all cases the transistors opened up and no collector to emitter short occurred in any transistor. In any event, the optional circuit in Figure 2 will give you that extra peace of mind when a very expensive radio is used with the power supply. The circuit in Figure 2 senses when the voltage exceeds 15 volts and causes the zener diode to conduct. When the zener diode conducts, the gate of the SCR is turned on and causes the SCR to short which blows the 15 amp fuse and shuts off the output voltage.

A 2N6399 (Tech America) was used for the SCR in the prototype but any suitable SCR can be used. While over voltage protection is a good idea, it should not be considered a substitute for large heat sinks. I personally feel the best protection from over voltage is the use of large heat sinks and a reliable current limiting circuit. Be sure to use large heat sinks along with heat sink grease for the 2N3055 transistors. I have used this power supply in my shack for several months on all kinds of transceivers from HF, VHF to UHF with excellent results and absolutely no hum. This power supply will be a welcome addition to your shack and will greatly enhance your knowledge of power supplies.

10 Amp 13.8 Volt Power Supply Circuit Diagram2

Parts
R1 1.5K ¼ Watt Resistor (optional, tie pins 6 & 5 of IC1 together if not used.)
R2,R3 0.1 Ohm 10 Watt Resistor (Tech America 900-1002)
R4 270 Ohm ¼ Watt Resistor
R5 680 Ohm ¼ Watt Resistor
R6,R7 0.15 Ohm 10 Watt Resistor (Tech America 900-1006)
R8 2.7K ¼ Watt Resistor
R9 1K Trimmer Potentiometer (RS271-280)
R10 3.3K ¼ Watt Resistor
C1,C2,C3,C4 4700 Microfarad Electrolytic Capacitor 35 Volt (observe polarity)
C5 100 Picofarad Ceramic Disk Capacitor
C6 1000 Microfarad Electrolytic Capacitor 25 Volt (observe polarity)
IC1 LM723 (RS276-1740) Voltage Regulator IC. Socket is recommended.
Q1 TIP3055T (RS276-2020) NPN Transistor (TO-220 Heat Sink Required)
Q2,Q3 2N3055 (RS276-2041) NPN Transistor (Large TO-3 Heat Sink Required)
S1 Any SPST Toggle Switch
F1 3 Amp Fast Blow Fuse
D1-D4 Full Wave Bridge Rectifier (RS276-1185)
T1 18 Volt, 10 Amp Transformer Hammond #165S18 (Tech America 900-5825)

Readmore → Build a 10 Amp 13 8 Volt Power Supply Circuit Diagram

Monday, 21 November 2016

Build a 25W Bridge Audio Amplifier with TDA2005

This is the 25W bridge audio amplifier built using single power IC TDA2005. Actually, the TDA2005 is a stereo power amplifier chip. It has two input channels and two output channel and delivers about 10W power output for each channel, since it connected in bridge mode then it will delivering up to 25W audio output. Take a note that the speaker terminals should not conected to the ground and mount the IC on the heatsink to prevent overheating.

25W Bridge Audio Amplifier with TDA2005 Circuit Diagram

Parts List:
R1 = 120K?
R2,5,6 = 1K?
R3,4 = 12?
R7,8= 1?
C1,5,7 = 220uF/25V
C2,10,11 = 100nF
C3,4 = 2.2uF/25V
C6,8 = 100uF/25V
C9 = 10uF/25V
IC1 = LM2005M / TDA2005

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Sunday, 20 November 2016

Build an AC Mains Short Circuit Protector Circuit Diagram

The simple short circuit and overload protector design presented here can be used for protecting valuable mains operated gadgets like amplifiers, TV sets, DVD players or any other similar appliance.Normally all sophisticated gadgets today incorporate an in built short circuit protector arrangement, yet still adding a more comprehensive external protection device could only benefit the connected system.

Moreover, for gadgets such as amplifiers which are home built this protection device could prove to be very effective and useful. Also for an hobbyist who prefers building electronic gadgets at home could be greatly benefited with the present idea.

The presented short circuit protector design works on a very basic principle and costs not more than a couple of dollars.

Let's learn the functioning details of the proposed circuit.

On applying power, the high current from the 220V input is dropped sufficiently by C1, rectified by D1 and filtered by C2 to feed the gate of the triac T1.

The triac conducts and switches ON the connected transformer primary thus switching ON the load which in this case is a power amplifier.

The transistor Q1 along with R1, R2 forms a current sensor stage.

R2 specifically is chosen such that it develops adequate voltage across itself at the specified dangerous high current threshold.

As usual the formula for determining R2 = 0.6/current(A)

As soon as the triggering voltage accumulates across R2, Q1 activates and sinks the gate voltage of the triac to ground making it switch off.

The regulation continues as long as the short or overload condition is not removed.

The above short circuit regulation ensures that the current level above the specified dangerous level is restricted safeguarding the precious devices associated with the connected amplifier.

If a latching feature is required for the above design, the emitter Q1 can be configured with an SCR and the SCR can be used for latching and switching off the triac.

AC Mains Short-Circuit Protector Circuit Diagram

Parts List

R1 = 100 ohms
R2 = see text
R3 = 1k
R4 = 10k
C1 = 0.33/400V
C2 = 1uf/250V
Q1 = BC547
Z1 = 12V/1 watt zener diode
T1 = BT136 or as per current rating
TR1 = As per load requirement specs.

Source By Swagatam

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Tuesday, 15 November 2016

Build a 10W 225 400mhz Linear Amplifier Circuit Diagram

Build a 10w 225-400mhz Linear Amplifier Circuit Diagram. This circuit broadband amplifier covers the 225-400 MHz military communications band producing 10 watt RF output power and operating from a 28 volt supply. The amplifier can be used as a driver for higher power devices such as 2N6439 and MRF327. The circuit is designed to be driven by a 50 ohm source and operate into a nominal 50 ohm load.

10W 225-400mhz Linear Amplifier Circuit Diagram

The input matching network consists of a section composed of C3, C4, Z2, C5 and C6. C2 is a dc blocking capacitor, and Tl is a 4:1 impedance ratio coaxial transformer. Z1 is a 50 ohm transmission line. A compensation network consisting of Rl, Cl, and LI is used to improve the input VSWR and flatten the gain response of the amplifier.

L2 and a small ferrite bead make up the base bias choke. The output network is made up of a microstrip L-section consisting of Z3 and C7, and a high pass section consisting of C8 and L3. C8 also serves as a dc blocking capacitor. Collector decoupling is accomplished through the use of L4, L5, C9, C10, Cll, C12, and C13.

Readmore → Build a 10W 225 400mhz Linear Amplifier Circuit Diagram