Here is the Dual power supply circuitfor lab.
You can select voltage levels are 3V,5V,6V,9V,12,15V at 1A
and -3V,-5V,-6V,-9V,-12V,-15V at 1A.
Use LM317 (for positive volt) and LM337 (for negative volt).
Controls Voltage Output by S2 For +Vout and S3 for -Vout.
The transformer is of 2A size. And the both IC holds heat sink.
Read detail more in a circuit.
Our friends are looking for a dual power supply positive, negative and ground for experiments various circuits.
In some times we need to have experiments about an OP-amp IC – LM741. Which must use level voltage power supply of +9 volts and -9 volts, or when we a preamplifiers circuit or tone control circuits but they use supply voltage of +15 volts and -15 volts
We think this circuit will respond to your needs certainly because…
- Can provide the positive, negative voltage at size 3, 5, 6, 9, 12 and 15 volts respectively and the current output under 1.5 amps.
- Easy to use with rotating selector switch to selects level voltage as you want. Do not have a voltmeter measure the output voltage.
It is circuits simple and cheap to make because the IC that have been popular are LM317 and LM337.
Recommended: 7805 regulator datasheet & pinout
How it works
As show figure below, here is a step-by-step oppress.
- There is the diode 1N4001 – D3 and D4 acting full-wave rectifier side the positive voltage. Then so filter waveform to smooth with a capacitor C1(2,200uF).
- Next, entered to the input of IC1(LM317T) that is a positive regulated IC, it can adjust the voltage to changing of 1.2-37 volts and provide the maximum output current of 1.5 amps.
- The output voltage can change as the value of resistor R2 and changes the resistance of R3 to R8, by selector switch S2 to choose the resistance as you want, to we have a voltage level from 3, 5, 6, 9, 12 and 15 volts.
- The capacitor C7(22uF) is determined impedance and reduce a transient on the output of IC1-LM317T.
- The capacitor C3(0.1uF) is used when we install the IC1 far from C1 too much.
- Capacitor C5(22uF) reduce the ripple signal before it is amplified when the high output voltage up.
- Capacitor C9 reduces the ripple that appears on the output.
- Both diode(1N4001) D5 and D7 for protects the IC1 from discharging of C7 and C5 when the input is shorted circuit.
- The negative section like the positive as above.
- The diode D1 and D2 are rectifier diode in a full-wave negative model, by has IC2-LM337T is the negative DC regulated IC. For all resistors and capacitors that also act as same as the positive as described above.
Recommended: LM317 Calculator
Also LM317 power supply circuits
Next ideas,if you want to other voltage in variable voltage form e.g. 4.5V,7.5V,13V, etc. You can add the VR1 in adj pin of the IC1-LM317 and IC2- LM337 look like to Best DC power supply 3Amp to adjust 1.2V-20V & 3V-6V-9V-12V
0-60 volt DC variable power supply using LM317&LM337 : So well circuit, start voltage at zero voltage! and higher maximun at 60 volts.
The circuit above list may be unnecessary for you. Because large. And too expensive. see this circuits better.
LM317 Linear power supply Regulator selector 1.5V,3V,4.5V,5V,6V,9V 1.5A
My first Variable DC Power Supply 1.2V to 30V 1A by LM317 It’s easy and cheap as possible.
These circuits require enough power supply. Do you have this one? If you do not have it. Look:Learn Many Power supply circuits
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