How to make a Bench Power Supply - No more dead batteries
Read through the instructions carefully before attempting. Also read the disclaimer.
Ever have been testing your project and run out of batteries right before you are finishing up or needed the correct voltage to test a SNES but didn't have a power supply? Well I have been there and I decided to build a bench power supply to fix these problems. It isn't as fancy as store bought powers supplies but it was allot cheaper. This power supply will go from 1.2V to 18V at 1.5A which makes it perfect for portable and electronics building.
SPECS:
- 1.2V to 15V Adjustable Range
- 1.5A max current output
- 120VAC input
- Digital readout of voltage and current draw of attached devices
- Full bridge rectifier and step down transformer
- Cooling fan to keep the box from burning
- Protection Diodes encase I stick the output on some high unknown voltage
- Chrome knob
- Authentic Oak wood casing
[Schematic for the Power Supply. Click for a larger version.]
Parts List:
- C1 4700uF 25V
- C2 10uF 25V
- C3 330uF 25V
- D Full Bridge Rectifier 50V 4A
- D1, D2 1N4001
- Fuse 1 Amp with Holder
- R1 5k Pot
- R2 220 ohms
- SW Toggle Off/On Switch
- T Transformer 12V-18V 2A
- U LM317
- Panel Meters
- Voltmeter
- Ammeter
- DC Cooling fan
I had most of these components already so my final bill was $30 (after panel meters which I will get to in a bit). The 4700uf cap was found in a Atari 5200 and the 330uF cap was in a old radio amplifier. The Bridge rectifier and transformer where also gutted from the radio. The rest of the stuff you can get from Radio Shack or from other devices. The LM317 will be hard to come by in devices so you may have to buy that like me. The LM317 will need a heat sink and most likely something you take apart will have one. You will also need a fan to cool the LM317 off. I had a bunch of CPU fans and used one of those.
I added some digital panel meters from Sure-Electronics. I bought the 2A DC and 20V DC LED digital panels. These have to be powered separately so a 7805 and 7812 will have to be used to power them. If you buy analog meters you will not have to worry about this. The Voltmeter goes across the Voltage out terminal and the Ammeter goes in series with the positive terminal.
[Insert picture of Voltmeter and Ammeter hookup Digital and analog set ups.]
For the box you can use anything you want. Radio Shack sells project boxes for cheap or you could make one like I did.
[The guts of the Power Supply.]
[Intake where the fan will go.]
[Vent for hot air.]
[Testing to see if they fit.]
[Done with building and now for testing.]
[Powering the Duop V1.]
Turned out pretty good. The Amp meter won't zero out without making it off by a half amp so I will have to live with .03A as 0. Guess that is what i get for buying $5 meters. So far I have powered motors, portables, consoles, calculators, remote control, Wiimote, Speakers, and other countless things with it.