Diy c64 psu

robin-elvin

New member
Joined
May 21, 2013
Posts
249
Country
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Region
Greater Manchester
Playing Russian Roulette with an original Commodore power supply is never a good idea so I decided to build my own.

I had trouble finding a box that would take the chunky transformer so I might change it in future.

The transformer has dual 9VAC outputs. One goes directly to the 64 and the other I've connected to a rectifier with smoothing cap to a 3A Turnigy UBEC which supplies 5VDC.

On the front panel I have a mains illuminated switch plus a nice blue LED indicating the 5VDC.

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Thanks :)

This time I got most of the parts from Maplin but I usually use Farnell.

Parts:

- 5mm LED Clip Concave
- 5mm Blue LED
- 220 Ohm resistor (to current-limit LED - you will need to find right value depending on LED)
- Snap-in Illuminated miniature round rocker switch Red
- DIN 7 Pin plug
- KBPC601 6A Bridge Rectifier
- 2200uF 35V Capacitor
- 3 Core 6A mains cable
- 6 Core Alarm cable
- 2 x M10 cable glands
- Single primary 240V - dual secondary 9V 50VA transformer
- 3A UBEC (in 5V output mode) http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=4319

Enclosure

Because of the size of the transformer the usual PSU enclosures weren't big enough. I eventually found this one on ebay http://www.ebay.co.uk/itm/251658412569?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
It's a little bit flimsy but was cheap enough to throw away if I find a better alternative.
 
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Thank you for that! I have some of the parts already so just need to grab a few more bits :)

I have a custom Amiga psu here that was built by whoever, got it from ebay really just to tear it down and find out what parts were used. The case appears to be built like a tank and can even be used outside as it has a rubber seal on the lid. I will get the exact measurements and any codes as it could well be a good find for your psu. Only thing is, the colour is grey.
 
You may find that using a switchmode PSU for the 5V will result in some noise on the 5V rail. This could end up as a buzz in the speaker or a ripple on the TV screen. If you notice any problems I'd recommend you add a smaller capacitor across the 5V output (in addition to the whopping 2200µf that you'Ve already got). The SMPS runs at 300kHz, so you should choose a value to match (supress) that frequency.

Bryce.
 
I'll double check with the scope but it seemed ok with my brief test.

The UBEC is rated <50mV p-p @2A/12v so should be ok but another cap wouldn’t hurt ☺

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