Compressor Circuit with 570/571 Compandor IC

Compressor circuit provide high gain for low amplitude input and provide low gain for high amplitude input. This action, in effect, produce a nearly constant amplitude even though the input has very high dynamic range (very high amplitude variation from time to time). The action of compression like this is needed in some situation, such as in maximizing modulation depth in broadcasting, or sustaining electric guitar signal which has very high variation between the plucking time and fading out. The following circuit has complementary input/output characteristic and unity gain at 0.775 VRMS input. Voltage gain through compressor is square root of 0.7/Vin. Vin is average input voltage. This circuit uses Signetics dual channel compandor IC. 570 has lower inherent distortion and higher supply voltage range (6-24 V) than 571 (6-18 V).

Sound Activated Lamp.

This simple circuit shown int the schematic diagram actives the switch using sound. We can use this circuit for various applications, such as automatic (sound-controlled) disco light or car’s LED light show. The Q1 amplify the audio from mic. The R1 is used to adjust the peak of signal to greater than about 0.7 volts, act as sensitivity adjuster. A certain level, the signal coming from microphone, after amplification by Q1, will trigger the SCR and light lamp I1. If we change the lamp with a relay, then we can get a sound-activated relay/switch, which can be used to control more powerful / high wattage high voltage lamps. If we use a relay, place a 1N4007 diode in parallel with the relay coil to prevent the back-emf from relay coil destroying the SCR.

List Component :

R1 >> 1K

R2 >> 4.7K

R3 >> 1K

VR1 >> 5K

C1 >> 0.47 mf/16V

Q1 >> HEP802

SCR >> C103

95 Watt Laptop Power Supply For Car.

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Datasheet semiconductor component: (PDF Format)

1. MBR1645
2. IRL2505
3. BD139
4. BD140
5. UC3843N


A laptop or anthology computer user while they are abroad from the home or appointment knows that eventually or after they will charge to bung into a mains aperture to top up the batteries. The car cigarette lighter atrium in the car is additionally an electrical aperture but it can alone accumulation 12 V. That’s no botheration for the Laptop Ability Accumulation declared here. The laptop ability accumulation declared actuality plugs into a car cigarette lighter atrium and produces a 19V nominal achievement voltage adjustable by + – 0.5V. The ascribe voltage ambit is from 9.2V to 15V and the achievement voltage shows acceptable adjustment alike with ample fluctuations of the ascribe voltage. The achievement can accumulation 5A continuosly with abrupt excursions up to 10A.

The ability semiconductor heatsinks of this laptop ability accumulation are dimensioned fo 5A connected so continued operation up to 10A will access amusement in the adapter and in acute cases will account the ascribe agglutinate to complain.

Cell Phone Battery Meter (3.6 Volt)

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1. LM339
2. TL431

This is a similar circuit to the above and provides a 4 LED bar graph indicating the voltage of a common 3.6 volt Lithium – Ion recharable cell phone battery. The reference voltage is provided by a TL431 programmable voltage source which is set to 3.9 volts where the TL431 connects to the 1K resistor. The lower reference for the LED at pin 14 is set with the 5K adjustable resistor.

The programmed voltage of the TL431 is worked out with a voltage divider (10K 5.6K). The adjustment terminal or junction of the two resistors is always 2.5 volts. So, if we use a 10K resistor from the adjustment terminal to ground, the resistor current will be 2.5/10000 = 250uA. This same current flows through the upper resistor (5.6K) and produces a voltage drop of .00025 * 5600 = 1.4 volts. So the shunt regulated output voltage at the cathode of the TL431 will be 2.5 + 1.4, or 3.9 volts.

Working out the LED voltages, there are three 390 ohm resistors in series with another adjustable (5K) resistor at the bottom. Assuming the bottom resistor is set to 2K ohms, the total resistance is 390+390+390+2000 = 3170 ohms. So, the resistor current is the reference voltage (3.9) divided by the total resistance, or about 3.9/ (390 + 390 + 390 + 2000) equals 1.23 mA. This gives us about .00123*2000= 2.46 volts for the bottom LED, and about .00123*390 = .48 volts for each step above the bottom. So, the LEDs should light at steps of 2.46, 2.94, 3.42, and 3.9. A fully charged cell phone battery is about 4.2 volts. You can adjust the 5.6K resistor to set the top voltage higher or lower, and adjust the lower 5K resistor to set the bottom LED for the lowest voltage. But you do need a 6 to 12 volt or greater battery to power the circuit.

Switch Mode Pre-Regulator

The botheration was that a voltage regulator had to bead the 18 volt capital ability accumulation voltage to 8 volts at 500ma to ability the CD player, crumbling 5 watts of ability and causing a lot of calefaction central the bunched unit. This ambit acts as an interference-free pre-regulator to abundantly abate the ability loss..

The achievement voltage of this ambit is artless by ability band fluctuations. Amount voltage aberration is alone abased on the on-resistance of Q2 and the amount of C2 (re: ripple). The achievement voltage can be set so that the ripple lulls are aloof aloft the drop-out voltage of the beeline regulator at best amount for best activity conservation. The college amount you aces for C2, the added activity you can save and the added abiding the pre-regulator’s achievement voltage.

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Datasheet semiconductor component. (PDF Format)

1. 2SK2314
2. 2N3904
3. IN4004
4. IN4744
5. IN4148
6. IN5231

LM78XX Positive Regulators Universal PCB for PSU

The 78XX family is ideally suited for this job, and with this little PCB you can easily build small Power Supplies for virtually every application.

The circuit is very simple:

The Alternating current is applied to X1 and rectifies by B1.

It charges a large Capacitor C1 to power the regulator.

The output voltage depends on the Regulator you use, e.g. 7805, 7812,7815…

Dimensionierung:

C1:4700u, with sufficient voltage Rating!

C2:0.33u

C3:0.1u

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Datasheet semiconductor download. (PDF Format)

1. LM78XX

LM2577 5V to 12V DC Converter step up Voltage Regulator

DC to DC step up voltage regulator. Wide input voltage 3.5Vdc to 40Vdc. This is Circuit DC to DC converter step up vol



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1. LM2577
2. IN5821

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Injector Pulse Width Monitor with LM324 ,LM3914

The schematic for the pulse width monitor. The heart of the circuit is the transistor current source which charges cap C10 to form an integrator. The theory is that the cap is charged and the voltage across it increases linearly for the amount of time that the injector is energized. As the injector is switched off the voltage in C10 is stored in cap C9 and then C10 is reset to 0 volts to get ready for the next cycle. The output of the circuit is the voltage across cap C9, this voltage is fed directly into U3 the bar graph chip to be displayed as a value between 1-10 on the LEDs. Potentiometer R31 sets the charge rate on C10 and basically sets the max injector on time that can be displayed.

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download datasheet the semiconductor component. (PDF Format)

1. LM324

2. LM3914

3. CD4058

4. LM7805

5. MN3206

6. MN3906

7. 2N2222

8. IN214

9. IN5233

Injector Pulse Width Monitor with LM324 ,LM3914 - [Link]

Nagative voltage generation using 555 timer

This 555 timer based PWM controller features almost 0..100% pulse width regulation using R1, while keeping the oscillator frequency relatively stable. The frequency is dependent on values of R1 and C1, values shown will give a frequency range from about 170 to 200 Hz. Any 555 chip will do, CMOS is fine as well. Diodes are not critical, I used 1N4148. Total cost of parts is about $2. As the whole thing is quite trivial, it’s very easy to build on prototyping board like I did.

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1. NE555

2. BD140

PWM Speed Motor Controller By IC 555-Electronic control circuit - [Link]

Power Amplifier with STK40xx Series Module

The series STK40xx is power amplifiers in completed form in a nutshell. They are characterized by the very good quality of sound and their low price. It is easy we make a power amplifier using only few external components. The STKxxxx amplifiers, for them we will find in enough eponymous stereo amplifiers , but also in enough activety loudspeakers. They do not need a lot of special knowledge of manufacture, only that attention in pins, in order to they do not break, and one good power supply. Details for the various types of series, voltage of work and the output power, see the Table A

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1. STK 40XX

Power Amplifier with STK40xx Series Module - [Link]

LM317T Voltage Regulator with Pass Transistor

The LM317T output current can be increased by using an additional power transistor to share a portion of the total current. The amount of current sharing is established with a resistor placed in series with the 317 input and a resistor placed in series with the emitter of the pass transistor.




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1. 2N2955
2. LM317A
3. IN4002

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0 - 300V Adjustable Power Supply.

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1. BUZ326
2. BC547

Introduction

To prevent my high voltage experiments to go up in smoke completely, I designed
a simple circuit which can provide an adjustable voltage source of 0 to 330 Volt..
The supply is short-ciruit proof: the current is limited to about 100mA.

Circuit description

TR1 is a 1:1 mains transformer; it is included for safety.

The mains voltage from TR1 is rectified with bridge D1 (1Amp / 500V) and large elcap C1.

T1 is switched as a source follower: the source of T1 will follow the voltage of the
wiper of R3. D2 is included to protect the gate of T1; although in theory not necessary
I strongly recommend to include it!

T2 and shunt resistor R2 build the current limiter. When the output current becomes too high, T2 will discharge
the gate of T1. This will prevent the current to become too high.
The value of R3 has been determined experimentally; it depends also on the Hfe of T2 so you may need to tune the value of R2.

Note that T1 needs a large heatsink: in worst case T1 will dissipate 330V x 100mA = 33Watt!
Instead of a BUZ 326 (400V/10.5Amp) you can also use an IRF740 (400V/10Amp).
The output impedance of the power supply is determined by the beta of T1, so the larger the MOSFET
the lower the output impedance!

9v Battery Voltage Monitor using a LTC1440 Comparator

This circuit turns on a LED whenever the voltage of a standard 9v battery connected to the circuit drops below 7.2 volts. It uses a LTC1440 comparator, which also contains a 1.18v reference diode. In standby mode, the circuit draws only 4uA.

Battery Monitor Circuits
Master Schematic Category List - David A. Johnson, P.E.

Variable Voltage and Current Power Supply

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Download list datasheet semiconductor parts. (PDF Format)

1. 2N3055
2. LM1458

Another method of using opamps to regulate a power supply is shown below. The power transformer requires an additional winding to supply the op-amps with a bipolar voltage (+/- 8 volts), and the negative voltage is also used to generate a reference voltage below ground so that the output voltage can be adjusted all the way down to 0. Current limiting is accomplished by sensing the voltage drop across a small resistor placed in series with the negative supply line. As the current increases, the voltage at the wiper of the 500 ohm pot rises until it becomes equal or slightly more positive than the voltage at the (+) input of the opamp. The opamp output then moves negative and reduces the voltage at the base of the 2N3053 transistor which in turn reduces the current to the 2N3055 pass transistor so that the current stays at a constant level even if the supply is shorted. Current limiting range is about 0 - 3 amps with components shown. The TIP32 and 2N3055 pass transistors should be mounted on suitable heat sinks and the 0.2 ohm current sensing resistor should be rated at 2 watts or more. The heat produced by the pass transistor will be the product of the difference in voltage between the input and output, and the load current. So, for example if the input voltage (at the collector of the pass transistor) is 25 and the output is adjusted for 6 volts and the load is drawing 1 amp, the heat dissipated by the pass transistor would be (25-6) * 1 = 19 watts. In the circuit below, the switch could be set to the 18 volt position to reduce the heat generated to about 12 watts.


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Variable 3 - 24 Volt / 3 Amp Power Supply

This regulated power supply can be adjusted from 3 to 25 volts and is current limited to 2 amps as shown, but may be increased to 3 amps or more by selecting a smaller current sense resistor (0.3 ohm). The 2N3055 and 2N3053 transistors should be mounted on suitable heat sinks and the current sense resistor should be rated at 3 watts or more. Voltage regulation is controlled by 1/2 of a 1558 or 1458 op-amp. The 1458 may be substituted in the circuit below, but it is recommended the supply voltage to pin 8 be limited to 30 VDC, which can be accomplished by adding a 6.2 volt zener or 5.1 K resistor in series with pin 8. The maximum DC supply voltage for the 1458 and 1558 is 36 and 44 respectively. The power transformer should be capable of the desired current while maintaining an input voltage at least 4 volts higher than the desired output, but not exceeding the maximum supply voltage of the op-amp under minimal load conditions. The power transformer shown is a center tapped 25.2 volt AC / 2 amp unit that will provide regulated outputs of 24 volts at 0.7 amps, 15 volts at 2 amps, or 6 volts at 3 amps. The 3 amp output is obtained using the center tap of the transformer with the switch in the 18 volt position. All components should be available at Radio Shack with the exception of the 1558 op-amp.




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1. 2N3055
2. 2N3053
3. 2N3904
4. LM1558

Voltage Regulator 5V-20V Project.

If you are looking for a low drop voltage regulator that is able to provide a power supply

of 1A with an output voltage of between 5V and 20V DC, National Semiconductor LM2941 Low Dropout Adjustable Regulator is one that you can choose to use. It has a typical dropout voltage of 0.5V which means that the input supply need only have to be 0.5V DC more than the desired output voltage. Its other features include internal short circuit current limit and reverse battery protection. As shown in the schematic below, the regulator has 5 pins which consists of the ON/OFF control, Input Voltage, Output Voltage, Ground and Adjustable pins. ON/OFF is used for the purpose of switching on and off of the regulator. The capacitors C1 and E1 are to be placed as close as possible to the regulator.

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The output of the circuit can be varied by varying the value of potentiometer VR1 from 5V DC to 20V DC. The input voltage is limited from 5.5V DC to 30V DC. Resistor R1 must be greater than 1K. The value of the VR1 that needs to be set is calculated from the formula given below:

VR1 = R1[(Vout/1.275) - 1] ohm

If R1=1K, Vout = 5V, VR1 should be set to 2.9K ohm.

If R1=1K, Vout = 20V, VR1 should be set to 14.7K ohm

Datasheet semiconductor component download. (PDF Format)

1. LM2941CT