Compact Variable Power Supply

Do you ever experienced a hassle when you started your hobbyist journey ? Which is always going away from the lab table when you try to power your project with a fixed voltage S.M.P.S power supply. You might have thought to buy a lab bench power supply. Which is usually for big voltage and currents. But your project only needed a lot less ampere and voltage. Most of the time we don't need those huge amounts of voltage and current of a big lab bench power supply. So instead of buying one you can follow my instructable and you can build your very own power supply.

let's start

PARTS YOU NEED TO BUILD IT :

1. Perfboard(5x5) - 1pcs

2. IN4007 diode (YOU CAN USE ANY DIODE WHICH HAS A Vf of 0.7V SHOULD BE GOOD) - 1pcs

3. Wire which has a crocodile clip on one end - 2pcs

4. solder wire - 70cm

5. enclosure - According to your need

6. 10k potentiometer

7. 1k resistor - 1pcs

8. 35v 47uF capacitor - 1pcs

9 . DC female jack

10. 12v 2A power supply which has a dc male jack on its output - 1pcs

11. HEART OF THE SYSTEM {3010KD adjustable voltage regulator} - 1pcs

TOOLS YOU NEED TO BUILD IT :

1. soldering iron with two tips (one for soldering and the other one for making holes in plastic) - 1pcs

2. hot glue gun - 1pcs

3. wire striper - 1pcs

4. cross tip screw driver - 1pcs

5. scissors -1pcs

THESE ARE THE IMAGES FOR THE PARTS YOU NEED

THESE ARE THE IMAGES FOR THE TOOLS YOU NEED

This is the schematic of our build

solder the IC 3010KD to perfboard as shown in the above picture

See the first pin of the ic is the on/off switch. If you connect that pin to supply voltage, it will turn on. If you connect that pin to ground, it will turn off. But I just connected it to the 2nd pin(supply voltage). Because I will control it with ac switch on the switch board. If you want an on/off switch, you can add it to the system. It's your wish.

According to the schematic R1 should be our 1k resistor. After that connect your potentiometer to the R2 position of the schematic and solder it to your perf board.

IMPORTANT :

When connecting the potentiometer connect the other end of 1k resistor to the middle pin of potentiometer.

There are another two pins left on the potentiometer.

If you connect ground to the first pin, you will get the voltage increased when you turn your potentiometer counter-clock wise.

If you connect ground to the third pin, you will get the voltage increased when you turn your potentiometer clock wise.

Connect the IN4007 diode to your circuit as it shown in the schematic.

When connecting the capacitor consider this:

If you are using a S.M.P.S power supply for input, you don't need to connect the Cin capacitor

If you are using a battery for input, you must connect the Cin capacitor.

But in both cases you must connect 47uF Cout capacitor.

Here I am using an S.M.P.S power supply so I connected only the Cout capacitor

Connect the dc jack gnd and one output wire(crocodile clipped wire) to gnd(pin 3) of the ic. Connect the dc jack plus wire to VIN(pin 2) of the ic. Connect the other output wire(crocodile clipped wire) to VO(pin 4) of the ic.

THERE YOU GO! YOU GOT YOURSELF THE COMPLETED CIRCUIT BOARD. GO AND DO SOME TEST RUNS.

This enclosure is an old enclosure of a cordless phone. I choose it because I like the shape of it. Change the tip of your soldering iron and put some holes for the potentiometer and for the dc jack. Put your circuit inside the case and hot glue the circuit according to your needs.

Connect your supply to your 12v power supply and adjust the voltage. If everything is ok, you will see the voltage changes in between the range of 1 - 12v.

HOW IT WORKS

The 3010-KD is an adjustable voltage regulator. We've normally seen the fixed voltage regulator for 12v and 5v. But this is an adjustable version. Here, the pin 5 always wants to maintain a 1v voltage difference between pin 5 to gnd. Here, our 1k resistor and 10k potentiometer is acting like a voltage divider. So it's feeding the output voltage back to the IC. But the voltage can be higher or lower than 1v. So the IC will change the output voltage in order to maintain the 1v on the adjust pin. That's how the output voltage change. Here I used a 1k resistor and 10k potentiometer as the voltage divider so according to the voltage divider formula when we apply 12v the output would be 1 and this is the maximum value our IC can output.

HERE YOU GO! YOU GOT YOURSELF A VERY OWN AND CHEAP VARIABLE POWER SUPPLY.

AND YOU LEARNED SOMETHING NEW . I GUESS SO.

HAVE FUN WITH IT.