I RECENTLY MAKE A VARIABLE POWER SUPPLY WITH LM 317 ( I WILL POST IT LATER). SO NOW NEED A VOLTMETER THAT CAN TELL ME THE OUT PUT VOLTAGE AND FIXED IT WITH THE POWER SUPPLY. I GOTO SHOPS TO FIND A SMALL VOLTMETER. BUT I CANT FIND ME SO I THINK TO MADE MY OWN VOLT METER .

NOW THE CHALLENGE IS HOW TO OUTPUT THE RESULT. THEN I HAVE A GOOD IDEA WITH LEDS.

I SEARCH IN INTERNET ABOUT MAKE A VOLTMETER AND COLLECT INFORMATION AND MAKE MY OWN VOLTMETER.

THIS VOLTMETER I HAVE MADE IS DEPEND ON ZENER DIOADS. I USE 3.6V, 6.3V, 9V, 12V, 15V AND 18 V. YOU CAN CUSTOMIZE IT AND MAKE IT READ ANY VOLTAGE!.

PLEASE GIVE ME VOTE FOR MAKE IT GLOW CONTEST AND Life Without Closets Contest

Step 1: Parts:------------)

So the part list is here:-- (I try to make it chep in just 1$)

1) Capacitor - 10uf/63v

2) Zener Dioads - any volt that you want to read I use - 3.6v, 6.3v , 9v, 12v, 15v, 18v

3) Leds- any color 3mm or 5mm led as you like. I have 6 leds because i have 6 output. you can use as your output number

4) Resistor - I use it for drive the leds and not to burn them. you calculate the value as your led. I use 4 piece of 390ohms for red led and 2 piece of 100ohms for blue led.

5) Some wire for connecting to source.

Additional Items :--

1) Bread board ( I recommend you to make the circuit in bred board first and test it there)

2) Solder and Soldering iron and universal pcb for final assembly.

Note:-- The zener dioads have very small voltage marking printed on them. So dont mix them up or you cant find the correct value.

Step 2: Circuit Layout:---

I have make this circuit layout:--

Step 3: Made It on Pcb:--

I prefer you to make and test it on a bread board first.

Use a piece of a universal pcb or a verro board and solder components on the board . double check the positive and negative side of the zener dioads. after soldering all thing cut of extra wire and add 2 wires to negative and positive. you are good to go now