Secret Diagram: Low

Showing posts with label Low. Show all posts

Sunday, 26 March 2017

Simple low high voltage cut circuit

Here is a circuit of simple low/high voltage cut circuit.Various safety circuit (low/high voltage cut) using IC.But in this circuit we are using two transistor for this circuit.

As we saw that the entire circuit is build using two transistor and very few of other components.Transistors are used to drive the relay.And also transistor T1 and T2 used to cut the supply in high and low voltage respectively.Where the variable resistors VR1 and VR2 is used to adjust the high and low voltages.As we know that when zener diode is connected to emitter of transistor then it get back bias voltage. The variable resistor VR1 and VR2 is so adjusted that it does not connect the transistor T2 and T1 in high and low voltage respectively. The load is connected through relay RL1.

PARTS LIST

Resistors
R1, R4 = 4.7 KΩ
R2, R3 = 220 Ω
VR1 = 10 KΩ
VR2 = 10 KΩ
Semiconductors
T1, T2 = BC148
ZD1, ZD2 = 5.6V
Miscellaneous
RL1 = 18V/500Ω

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Tuesday, 14 March 2017

Low Range AM Radio Transmitter Circuit Diagram

Simple radio transmitter for transmission up to 25 metres. It is basically an AM modulator whose signal can be received on the normal AM radio. It can also be used as an AM radio tester.

IC 555 (IC1) is used as a free running multivibrator whose frequency is set above 540 kHz. Here the circuit is designed for a frequency of around 600 kHz. The frequency of the multivibrator can be calculated as follows:

f=1.443(R1+2R2)C1

Low-Range AM Radio Transmitter Circuit Diagram

where resistors R1 and R2 are in ohms, capacitor C1 is in microfarads, and frequency f is in hertz. This frequency can be changed by simply replacing R2 with a variable resistor or C1 with gang capacitors. But it may increase the complexity of the circuit. A condenser microphone is used for speaking.

The IC 555 multivibrator is used as a voltage-to-frequency converter. The output of the condenser microphone is given to pin 5 of IC1, which converts the input voltage or voice signal into its appropriate frequency at output pin 3. This frequency produces an electromagnetic wave, which can be detected by a nearby radio receiver, and you can hear your own voice in that radio. Note that the receiver should be AM type. If there is no noise in receiver, tune it to 600 kHz.

The circuit operates off a 9V regulated power supply or a 9V battery. For antenna, connect 2-3m long wire at pin 3.

This circuit costs around Rs 30.

Sourced By: EFY. Author name: Parag Purushottam Ingle

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Friday, 10 March 2017

Low ripple power supply schematic

Simple schematic above is a circuit of power supply that can operate at high current with very small ripple voltage. How it works similiar to the high power class AB amplifiers, with the same quality. T1,T2 ,and R2 can also be called a power NPN-Darlington transistor. ZD1 and R1 as a supplier of voltage on the transistor base and filtered by C2. ZD1 can be slected with formulated (Figure 1.0) . For the C2 can be selected in accordance with the degree of smoothness as its value is effectively combined with the multiplied gain of the Transistor T1 and T2, assumsing minimum hfe for T1 and T2 , C=100x15(T1) x 25 (T2) = 37,000uF, adjust the voltage C2 with the input voltage, but must be higher than input voltage.

Part List :
R1 = 2K2
R2 = 56R
R3 = 10K
C1 = 1500uF
D1-D4 = Didode 6A
T1 = 2N3054
T2 = 2N3055

Figure 1.0

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Wednesday, 8 March 2017

Now Low Cost Arduino Thermal Camera

Do you still remember the H1N1 outbreak in Asia? The manifestations are usually flu-like symptoms which includes fever, cough and colds. The best way to detect fever when people are arriving from the affected areas was to use a thermal camera. These were widely used in Asian countries especially on airports but not all can afford one because it’s very expensive.

Hacks and Mods: Low-Cost Arduino Thermal Camera

We can all agree that this is the greatest deal ever! A thermo-cam which costs around 100$, now there is no reason it can’t be bought by even poor countries to help prevent the spread of the disease. Credit must be given to inventions like this because it’s really a big help.

Readmore → Now Low Cost Arduino Thermal Camera

Sunday, 29 January 2017

Low Loss Step Down Converter

This circuit arose from the need of the author to provide a 5 V output from the 24 V battery of a solar powered genera-tor. Although solar power is essentially free it is important not to be wasteful especially for small installations; if the battery runs flat at midnight you’ve got a long wait before the sun comes up again. The basic requirement was to make an efficient step-down converter to power low voltage equipment; the final design shown here accepts a wide input voltage from 9 to 60 V with an output current of 500 mA. The efficiency is very good even with a load of 1 mA the design is still better than a standard linear regulator. The low quiescent current (200 µA) also plays a part in reducing losses.

Some of the components specified (particularly the power MOSFET) are not the most economical on the market but they have been deliberately selected with efficiency in mind.

Low Loss Step Down Converter Circuit Diagram

When power is applied to the circuit a reference voltage is produced on one side of R2. D1 connects this to the sup-ply (pin 7) of IC1 to provide power at start-up. Once the circuit begins switching and the output voltage rises to 5 V, D2 becomes forward biased and powers the IC from the output. Diode D1 becomes reverse biased reducing current through R1. When the circuit is first powered up the voltage on pin 2 of IC1 is below the reference voltage on pin 3, this produces a high level on output pin 6. The low power MOSFET T1 is switched on which in turn switches the power MOSFET T3 via R5 and the speed-up capacitor C4, the output volt-age starts to rise.

When the output approaches 5 V the voltage fed back to the inverting input of IC1 becomes positive with respect to the non inverting input (reference) and switches the output of IC1 low. T1 and T3 now switch off and C3 transfers this negative going edge to the base of T2 which conducts and effectively shorts out the gate capacitance of T3 thereby improving its switch off time.

The switching frequency is not governed by a fixed clock signal but instead by the load current; with no load attached the circuit oscillates at about 40 Hz while at 500 mA it runs at approximately 5 kHz. The variable clock rate dictates that the output inductor L1 needs to have the relatively high value of 100 mH. The coil can be wound on ferrite core material with a high AL value to allow the smallest number of turns and produce the lowest possible resistance. Ready-made coils of this value often have a resistance greater than 1 ? and these would only be suitable for an output load current of less than 100 mA.

The voltage divider ratio formed by R4 and R3 sets the output voltage and these values can be changed if a different out-put voltage is required. The output volt-age must be a minimum of 1 V below the input voltage and the output has a minimum value of 4 V because of the supply to IC1.

A maximum efficiency of around 90 % was achieved with this circuit using an input voltage between 9 and 15 V and supplying a current greater than 5 mA, even with an input voltage of 30 V the circuit efficiency was around 80 %. If the circuit is used with a relatively low input voltage efficiency gains can be made by replacing D4 with a similar device with a lower reverse breakdown voltage rating, these devices tend to have a smaller for-ward voltage drop which reduces losses in the diode at high currents. At higher input voltage levels the value of resistor R1 can be increased proportionally to reduce the quiescent current even further.

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Saturday, 7 January 2017

Using the high low side driver IR2110 explanation and plenty of example circuits

In many situations, we need to use MOSFETs configured as high-side switches. Many a times we need to use MOSFETs configured as high-side and low-side switches. Such as in bridge circuits. In half-bridge circuits, we have 1 high-side MOSFET and 1 low-side MOSFET. In full-bridge circuits we have 2 high-side MOSFETs and 2 low-side MOSFETs. In such situations, there is a need to use high-side drive circuitry alongside low-side drive circuitry. The most common way of driving MOSFETs in such cases is to use high-low side MOSFET drivers. Undoubtedly, the most popular such driver chip is the IR2110. And in this article/tutorial, I will talk about the IR2110.

You can download the IR2110 datasheet from the IR website. Here's the download link:

www.irf.com/product-info/datasheets/data/ir2110.pdf

First let’s take a look at the block diagram and the pin assignments and pin definitions (also called lead assignments and lead definitions):

Fig. 1 - IR2110 block diagram (click on image to enlarge)

Fig. 2 - IR2110 Pin/Lead Assignments (click on image to enlarge)

Fig. 3 - IR2110 Pin/Lead Definitions (click on image to enlarge)

Notice that the IR2110 comes in two packages – 14 pin through-hole PDIP package and the 16-pin surface mount SOIC package.

Now let's talk about the different pins.

VCC is the low-side supply and should be between 10V and 20V. VDD is the logic supply to the IR2110. It can be between +3V to +20V (with reference to VSS). The actual voltage you choose to use depends on the voltage level of your input signals. Here’s the chart:

Fig. 4 - IR2110 Logic "1" Input Threshold vs VDD (click on image to enlarge)

It is common practice to use VDD = +5V. When VDD = +5V, the logic 1 input threshold is slightly higher than 3V. Thus when VDD = +5V, the IR2110 can be used to drive loads when input “1” is higher than 3 point something volts. This means that it can be used for almost all circuits, since most circuits tend to have around 5V outputs. When you’re using microcontrollers the output voltage will be higher than 4V (when the microcontroller has VDD = +5V, which is quite common). When you’re using SG3525 or TL494 or other PWM controller, you are probably going to have them powered off greater than 10V, meaning the outputs will be higher than 8V when high. So, the IR2110 can be easily used.

You may lower the VDD down to about 4V if you’re using a microcontroller or any chip that gives output of 3.3V (eg dsPIC33). While designing circuits with the IR2110, I had noticed that sometimes the circuit didn’t work properly when IR2110 VDD was selected as less than +4V. So, I do not recommend using VDD less than +4V.

In most of my circuits, I do not have signal levels which have voltages less than 4V as high and so I use VDD = +5V.

If for some reason, you have signals levels with logic “1” having lower than 3V, you will need a level converter / translator that will boost the voltage to acceptable limits. In such situations, I recommend boosting up to 4V or 5V and using IR2110 VDD = +5V.

Now let’s talk about VSS and COM. VSS is the logic supply ground. COM is “low side return” – basically, low side drive ground connection. It seems that they are independent and you might think you could perhaps isolate the drive outputs and drive signals. However, you’d be wrong. While they are not internally connected, IR2110 is a non-isolated driver, meaning that VSS and COM should both be connected to ground.

HIN and LIN are the logic inputs. A high signal to HIN means that you want to drive the high-side MOSFET, meaning a high output is provided on HO. A low signal to HIN means that you want to turn off the high-side MOSFET, meaning a low output is provided on HO. The output to HO – high or low – is not with respect to ground, but with respect to VS. We will soon see how a bootstrap circuitry (diode + capacitor) – utilizing VCC, VB and VS – is used to provide the floating supply to drive the MOSFET. VS is the high side floating supply return. When high, the level on HO is equal to the level on VB, with respect to VS. When low, the level on HO is equal to VS, with respect to VS, effectively zero.

A high signal to LIN means that you want to drive the low-side MOSFET, meaning a high output is provided on LO. A low signal to LIN means that you want to turn off the low-side MOSFET, meaning a low output is provided on LO. The output on LO is with respect to ground. When high, the level on LO is equal to the level of VCC, with respect to VSS, effectively ground. When low, the level on LO is equal to the level on VSS, with respect to VSS, effectively zero.

SD is used as shutdown control. When this pin is low, IR2110 is enabled – shutdown function is disabled. When this pin is high, the outputs are turned off, disabling the IR2110 drive.

Now let’s take a look at the common IR2110 configuration for driving MOSFETs in both high and low side configurations – a half bridge stage.

Fig. 5 - Basic IR2110 circuit for driving half-bridge (click on image to enlarge)

D1, C1 and C2 along with the IR2110 form the bootstrap circuitry. When LIN = 1 and Q2 is on, C1 and C2 get charged to the level on VB, which is one diode drop below +VCC. When LIN = 0 and HIN = 1, this charge on the C1 and C2 is used to add the extra voltage – VB in this case – above the source level of Q1 to drive the Q1 in high-side configuration. A large enough capacitance must be chosen for C1 so that it can supply the charge required to keep Q1 on for all the time. C1 must also not be too large that charging is too slow and the voltage level does not rise sufficiently to keep the MOSFET on. The higher the on time, the higher the required capacitance. Thus, the lower the frequency, the higher the required capacitance for C1. The higher the duty cycle, the higher the required capacitance for C1. Yes, there are formulae available for calculating the capacitance. However, there are many parameters involved, some of which we may not know – for example, the capacitor leakage current. So, I just estimate the required capacitance. For low frequencies such as 50Hz, I use between 47µF and 68µF capacitance. For high frequencies like 30kHz to 50kHz, I use between 4.7µF and 22µF. Since we’re using an electrolytic capacitor, a ceramic capacitor should be used in parallel with this capacitor. The ceramic capacitor is not required if the bootstrap capacitor is tantalum.

D2 and D3 discharge the gate capacitances of the MOSFET quickly, bypassing the gate resistors, reducing the turn off time. R1 and R2 are the gate current-limiting resistors.

+MOSV can be up to a maximum of 500V.

+VCC should be from a clean supply. You should use filter capacitors and decoupling capacitors from +VCC to ground for filtering.

Now let’s look at a few example application circuits of the IR2110.

Fig. 6 - IR2110 circuit for high-voltage half-bridge drive (click on image to enlarge)

Fig. 7 - IR2110 circuit for high-voltage full-bridge drive with independent switch control (click on image to enlarge)

In Fig. 7 we see the IR2110 being used to drive a full bridge. The functionality is simple and you should understand it by now. A common thing that is often done is that, HIN1 is tied/shorted to LIN2 and HIN2 is tied/shorted to LIN1, enabling the control of all 4 MOSFETs from 2 signal inputs, instead of 4 as shown below in Fig. 8.

Fig. 8 - IR2110 circuit for high-voltage full-bridge drive with tied switch control - control with 2 input signals (click on image to enlarge)

Fig. 9 - Using the IR2110 as a single high-voltage high-side driver (click on image to enlarge)

In Fig. 9 we see the IR2110 being used as a single high-side driver. The circuit is simple enough and follows the same functionality described above. One thing to remember is that, since there is no low-side switch, there must a load connected from OUT to ground. Otherwise the bootstrap capacitors can not charge.

Fig. 10 - Using the IR2110 as a single low-side driver (click on image to enlarge)

Fig. 11 - Using the IR2110 as a dual low-side driver (click on image to enlarge)

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If you've had failures with IR2110 and had driver after driver, MOSFET after MOSFET get damaged, burn and fail, I'm pretty sure that it's due to you not using gate-to-source resistors, assuming of course that you designed the IR2110 driver stage properly. NEVER OMIT THE GATE-TO-SOURCE RESISTORS. If you're curious, you can read about my experience with them here (I have also explained the reason that the resistors prevent damage):

http://www.blogspot.com/2016/10/magic-of-knowledge.html

For further reading, you should go through this:

http://www.irf.com/technical-info/appnotes/an-978.pdf

I have seen in many forums that people struggle with designing circuits with IR2110. I too had a lot of difficulty before I could confidently and consistently build successful driver circuits with IR2110. I have tried to explain the application and use of IR2110 thoroughly through explanation and plenty of examples and hope that it helps you in your endeavors with IR2110.

Readmore → Using the high low side driver IR2110 explanation and plenty of example circuits

Wednesday, 4 January 2017

Inverter as High Voltage Low Current Source Using by 555 timer

This is a simple Electronic Circuit Projects of Inverter as high voltage low current source using by 555 timer IC. The circuit is capable of providing power for portable Geiger counters, dosimeter chargers, high resistance meters, etc.

Inverter as High Voltage Low Current Source Circuit Diagram:

The 555 timer IC is used in its multivibrator mode, the frequency adjusted to optimize the transformer characteristics. When the output of the IC is high, current flows through the limiting resistor, the primary coil to charge C3. When the output is low, the current is reversed With a suitable choice of frequency and C3, a good symmetric output is sustained.

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Sunday, 1 January 2017

Low Cost and Low Voltage Flasher

This is Simple low-Cost Electronic Circuit of Low voltage flasher Circuit. Applying voltage to the circuit triggers SCR1. With SCRl on, the voltage on the anode of SCR2 rises until SCR2 triggers to commu-tate SCRl.

Low Voltage Flasher Circuit Diagram:

The voltage on the gate of SCRl will swing negative at this time, and only after a positive potential of 0 volt is once again attained, will SCRl retrigger The circuit could be used for higher voltage levels, but the peak negative voltage on the gate of SCRl must be limited to less than 6 volts.

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Saturday, 17 December 2016

TBA820 low power audio amplifier

TBA820 , KA2201 , LM820 , U820 amplifier

At this time amplifier circuit based on IC KA2201, TBA820M, LM820M, and U820. You can use all ic is the series under the scheme. This amplifier circuit has a very small output power or low at 2W. Required supply voltage from 3 volts to a maximum of 16 volts.

Below is a scheme of this power amplifier

TBA820 , KA2201 , LM820 , U820 rangkaian amplifier

Part List

R1 = 100K

R2 = 120R

R3 = 100R

C1 = 100nF

C2 = 100uF
C3 = 470uF
C4 = 220pF

C5 = 47uF

C6 = 100uF

IC = KA2201 , LM820M , TBA820M , U820M

Readmore → TBA820 low power audio amplifier

Tuesday, 29 November 2016

Low Cost 1 5 to 9 Volts Inverter

This electronic circuit project is very interesting and low-cost electronic project, some electronic circuits we need a 9 volts power supply, but we need to use a battery if that device is mobile. In many cases we don’t have a 9 volts battery or we don’t have enough space to put a 9 volts battery inside the device, so this case we can use a this inverter circuit that will convert 1.5v to 9v to take the place of those expensive 9v batteries.

1.5 to 9 Volts Inverter Circuit Diagram:

The input voltage for this inverter can be from 1.5 volts, up to 4.5 volts. When no current is being drawn from the output the current is less than 10mA.

This inverter circuit is very simple requiring few components, but it can be used only for projects that require low current. The L1 coil must have 60 turns on a 10 mm ferrite slug 15 mm long, using a 0.25 mm diameter enameled wire.

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Wednesday, 16 November 2016

Low Cost 3 volts FM Transmitter

This very Simple Electronic Project and useful circuit diagram of an FM transmitter is sown in this schematic. This fm transmitter circuit is very simple and it has a acceptable transmission. The signal transited from this fm transmitter circuit can be received at almost 300 meters in open air The circuit require a 3volts operating voltage and can be tuned anywhere in the FM band.

Low-Cost 3 volts FM Transmitter Circuit Diagram:

You can use this rf transmitter circuit to transmit signal from your house to garden or from room to room . To listen the signal you can use any radio (portable or not ) that can work on FM band . The coil should be about 3mm in diameter and 5 turns. The wire is tinned copper wire, 0.61 mm in diameter.

After the coil in soldered into place spread the coils apart about 0.5 to 1mm so that they are not touching. If you don’t have a trim cap you can use a fixed value capacitor and you can vary the TX frequency by adjusting the spacing of the coils or placing a small piece of ferrite inside the coil, but the better way to change the transmission frequency is to use a variable capacitor.

Connect a half or quarter wavelength antenna (length of wire) to the aerial point. At an FM frequency of 100 MHz these lengths are 150 cm and 75 cm respectively. The calibration of this rf transmitter circuit is very simple and you need just to place a radio at some distance from the transmitter and set it somewhere about 89-90MHZ (chose the transmission frequency) and after that vary the transmitter oscillator frequency, by modifying the value of the capacitor. The transmission frequency is set to the desired frequency just when you can hear the transmitted signal.

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Saturday, 12 November 2016

Simple Low Distortion Audio Amplifier Circuit Diagram

This is the Simple Low Distortion Audio Amplifier Circuit Diagram. The circuit was designed and sold as a card by a purveyor of surplus components but, even using mostly manufacturer's rejected transistors, we managed to get about 0.02% total harmonic distortion at 30 watts with a ±25v power supply into 8 ohms.: no bad figure even in these days of MOSFET and ICs. In 1977 anything below 0.1% was considered excellent. And this figure was pretty repeatable without doing much selection.

The problem of course is that since I haven't touched this amplifier for many a year I have absolutely no idea what modern transistor types one should use for it but they are not critical: output transistors and drivers need to be the correct type but the other transistors can be small signal types - as long as they can handle the full voltage between + and - supplies.

Simple Low Distortion Audio Amplifier Circuit Diagram

Tr1 and Tr2 are a long-tailed pair (LTP to save typing). It is quite common to have a LTP in an audio amp but this is different: this is a complimentary LTP. As far as I am aware no one else had used a complimentary LTP at the time, though I have since seen it used in one other circuit. So I guess the circuit is unique to the author. One of the things that limits the performance of a conventional LTP is that the tail source loads the common emitters. In a complementary LTP this can't happen as there is no tail current source so that all the current of one transistor has to flow through the other.

Tr2's collector current flows into D1 and D2 which develop a voltage: this is used to bias Tr8 as a constant current source for Tr4's collector. The fact that Tr4 is working at a constant current defines its base-emitter voltage which must be developed across R4. This defines a current in R4 and this is the current that the LTP must operate at - so the ring of four transistors (Tr1, 2, 3, & 4) is self biasing and all transistors work at their best with minimum unwanted loads and biasing detracting from the performance. Tr4 is actually one of the most critical transistors: in the original circuit it was selected for Vce greater than 75v. Most Texas BC212s passed easily. Lower voltage transistors caused an increase in distortion level.

There is always a down side to any circuit: in the conventional LTP the base-emitter voltages tend to cancel each other out. In the complimentary LTP they add so there is a drop of about 1.2v between the two bases: this must be cancelled in the biasing chain and, since this circuit was designed for operation over a wide range of supply voltage, I had to be a little clever. Because of the constant current operation of the LTP and the constant voltage drop across D1 & D2, there is also a constant voltage across R14. This drop is used to lift up the bottom of the biasing chain (R1 and R11) so that the output sits at around half supply voltage, over a wider supply range.

D3 and D4 develop a bias voltage so that the output transistors are at the correct point, slightly conducting, to minimise crossover distortion.

The output transistors are complimentary (the original design used MJE2011 and MJE2021) and are driven by complimentary drivers: PNP driving NPN and vice versa. This arrangement is not only pleasingly symmetrical but gives better performance that the more common Darlington arrangement - the full gain of all the transistors is used and there is more internal feedback and less voltage drop.

The output current is monitored in the two resistors R7 and R22 (180 milliohms). The current limiting is unusual in that it works inside the input ring at an earlier stage than normal. This has an advantage that the current limiting transistors do not load the drive circuitry - which will introduce distortion. The slight down side is that there may be a slight tendency to oscillation when in current limit. R3 and R14 are necessary to restrict the current availability when the current limit engages. R5 and R19 are present to make the current limit vary with the voltage across the power transistors to avoid the second breakdown region of power transistors.

The points shown connecting terminals 1-2 and 6-7 are 'scratch-through tracks'. 1 and 2 are the power and signal earths: to keep distortion in a stereo system to a minimum the currents in these must never share the same path so in a stereo system four earth wires are run to the system's common earth point - a 'spider' common earth - and this means breaking the link. The link between 6 & 7 is in the feedback path and there are times when this can usefully be broken - one 'cheapskate' was to fit a tone control circuit here (see below). It works fine but is a bit of an insult to such a low-distortion design!. A third break point is in the collector of Tr2. Breaking this shuts down the amplifier completely and safely. Is a thermal switch is to be fitted, this is the place.

Overall negative feedback is in two parts: D.c. is fed back via R13: there is 100% d.c. feedback. A.c. feedback is via R12 and R17. Note the output capacitor is inside this feedback loop (speaker connects between terminal 5 and negative) which extends the low frequency response.

Another feature is the accessibility of both ends of the output coupling capacitor: being designed for a junk shop, they didn't want to use expensive capacitors! So for extra bass performance an additional capacitor can easily be connected.

The circuit can also be driven as a low input impedance: break 6-7, short pin 8 to C4's positive and apply input to pin 6. In this mode the input distortion is actually better: my original notes show as low as 0.01%!

When building a low-distortion amplifier, layout is vital. In fact to get distortion around 0.02% requires a lot of skill and experience. The problem is that the current in the output stage alternates between the two power transistors so is a 'rectified' version of the input. Now there is no such thing as a 'wire'. Any real piece of wire or copper track is a resistor with associated inductance and capacitance. If the high current, rectified output signal mixes in the same 'piece of wire' with the input signal the distortion in the rectified output current will feed into the input and cause the overall distortion to rocket. This is something which cannot properly be taught but has to be experienced. A skilled audio engineer will spend his lifetime learning about it.

Another interesting idea which is not shown is to fit a resistor between pin 3 and R18. This decreases the current at higher voltages and allows it to increase at low supply voltages. My notes show that this had a considerable advantage for low voltage operation because it increases the bias. It also is positive feedback which increase the open-loop voltage gain. It never got incorporated and I don't remember the details.

Tone controls

The circuit shows a simple (but effective) way of adding tone controls around the power amp. This does increase the distortion a little so it is not as 'hi-fi' a solution as a separate tone control stage, but it is simple and quite effective.

To use the tone controls you must break the link between 6 and 7 on the circuit. Also the 150K resistor, R13, should be decoupled. Replace it by two 68K resistors in series. The centre point of these two connects to the positive of a 1µ electrolytic whose negative connects to the earth (0v) line. This stops R13 acting as negative feedback which otherwise would shunt the tone controls.

Sourced by : Author: Richard Torrens
Site hosted by Arachsys

Readmore → Simple Low Distortion Audio Amplifier Circuit Diagram

Thursday, 10 November 2016

A Low Cost Hearing Aid Circuit Diagram

This low-cost, general-purpose electronic hearing aid works off 3V DC (2x1.5V battery). The circuit can be easily assembled on a veroboard. For easy assembling and maintenance, use an 8-pin DIP IC socket for TDA2822M.

Circuit Diagrams:

A Low Cost hearing Aid Circuit

Parts:
P1 = 10K
R1 = 2.2K
R2 = 330K
R3 = 680R
R4 = 33R
R5 = 100R
R6 = 4.7R
R7 = 4.7R
R8 = 220R
C1 = 0.01uF-10V
C2 = 100nF-63V
C3 = 47uF-10V
C4 = 10uF-10V
C5 = 0.01uF-10V
C6 = 100uF-10V
C7 = 100nF-63V
C8 = 100nF-63V
D1 = Red LED
Q1 = BC547
IC1 = TDA2822M
EP1 = Mono Earphone 32R
SW1 = On-Off Switch

Circuit Operation:

In this circuit, transistor Q1 and associated components form the audio signal preamplifier for the acoustic signals picked up by the condenser microphone and converted into corresponding electrical signals. Resistor R5 and capacitor C3 decouple the power supply of the preamplifier stage. Resistor R1 biases the internal circuit of the low-voltage condenser microphone for proper working. The audio output from the preamplifier stage is fed to the input of the medium-power amplifier circuit via capacitor C2 and volume control P1.

The medium-power amplifier section is wired around popular audio amplifier IC TDA2822M (not TDA2822). This IC, specially designed for portable low-power applications, is readily available in 8-pin mini DIP package. Here the IC is wired in bridge configuration to drive the 32-ohm general-purpose monophonic earphone. Red LED (D1) indicates the power status. Resistor R8 limits the operating current of D1. The audio output of this circuit is 10 to 15mW and the quiescent current drain is below 1 mA.

Source by : Streampowers

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Saturday, 5 November 2016

Low cost Pump Controller Circuit Diagram

This is a project of Low cost Pump Controller Circuit Diagram. This simple but effective circuit can be used to control water level in a container. The prototype is used to pump water out of a bucket that collects condensation from a home air-conditioning system. The design is based around a 555 timer (IC1). Although the timer in configured as a mono-stable, it lacks the usual timing capacitor from pin 6 to ground. Instead, a metal probe inserted in the water provides a current path to a second, grounded probe. When the water level in the container reaches a third ("high") probe, the trigger input (pin 3) is pulled low, switching the 555 output high and energizing the relay via transistor Q1.

Pump Controller Circuit diagram:

Cheap Pump Controller Circuit Diagram

Once the water level drops below the "low" probe, the threshold input (pin 6) swings high, switching the output (pin 3) low and the relay and pump off. The two 100kΩ pull-up resistors can be replaced with larger values if more sensitivity is required (eg, if the 555 doesn’t trigger). A switch (S1) can be included to bypass the relay for manual emptying. The "low" probe should be positioned so that the pump doesn’t run dry.

The high level probe is placed at the level that you want the pump to start. Since the water is held at ground potential, you must use stainless steel or copper wire to slow corrosion. With water fountain pumps available for less than $10, this circuit offers a cheap alternative for those who have an air-conditioner on an internal wall and don’t want to be continually emptying the bucket on humid days.

Readmore → Low cost Pump Controller Circuit Diagram