PSU for MidiBox SID

Parts Questions
1

Hi !

I’ve already post in french, but I didn’t receive any answer…

I’m building a MidiBox Sid with a DINX, a LTC module and a LCD.

But something doesn’t let me sleep… How to correctly power my future synth ?

Thorsten’s site is not clear about this point… I don’t think to use a c64 psu…

So,  may I use a standalone 15 Vac power supply, or may I have to use a dual voltage transformer ?

I’m affraid that the unit may be noisy if I put the transformer inside the box…

Thank you for your experience feedback…

If these points were already explain, I apologize… but I searched in vain.

2

Hi,

w/o the C64 PSU it’s better to use seperate power supplies. One for the SID module (15V/100 mA should be ok), another for the digital modules (7V/500 mA are possibly enough)

It can work with a single PSU (I used this configuration at the beginning), but the 7805 of the core will get very hot, especially when additional consumers (esp. backlit LCD) are connected.

Hope that it’s clear now.

Best Regards, Thorsten.

3

Hi Thorsten,

I’m please to have a clear answer ! I suppose that you’re a busy guy, but if you could write a note about this point in the Midibox SID pages.

I’m a little bit sad because I found in the chaos of my archives a nive wallwart 15v dc.

I’ll study how to power my midibox at the best.

Thank you for your help,

Ludo

4

you can pick up c64 psu’s on ebay regulary i got one for £1

5

Hi All,

I’m planning on building a small MidiBox SID Step A with just single 8580, an LCD and 2 x DIN’s. Is it best to use the C64 power supply, or can it be powered by a single transformer without overheating the 7805?

Cheers,

  • Adam
6

as TK stated before, you should either use the C64 PSU or 2 seperate wallwart PSU’s

question @ all:

wouldn’t it be possible to put the 7805 behing the 7812 of the sid module? in this way the 7812 would get the 15v from the wallwart and the 7805 could run from the 12V?

i wanted to use this setup for my SEQ as well :wink:

7

Finally I’ve found in the old electronic parts I’ve collected a transformer that delivers 18Vac (for SID module) and 10Vac (for Core module).

The system works but as I flash the PIC late yesterday night, I didn’t take the time to let the unit work for a long time. So I didn’t see if the regulator became very hot.

This transformer may take place in the box.

ludo

8

I’m interested in building a MidiBox SID with an internal power supply so I can avoid the annoyance of wall warts  What do you guys think of the open-frame switching power supplies on page 138 of the Jameco catalog (#251, Feb 2005)?  Would an enclosed PS be a better choice for keeping hum out of the SID modules?  What wattage is ideal?  I’ve seen some designs here that use a simple transformer and not much else, depending on the bridge rectifiers on the modules to get DC.  To me, this seems like asking for hum troubles.