Power Supply for MIDIBOX SID

[bleeptor]

Hi! I'm building my MIDIBOX SID with a 6581 chip, but I'm still not sure of which power supply should I use, or if I'll need 2 different power supplies for the 2 different voltages. I've read all about the original C64 power supply to be the best option, but unfortunately my commodore didn't have it. Is there another way?

[phunk]

Basically a a core module is running on 5V while the audio part of an SID module requires 12V (SID6581) resp. 9V (SID8580/6582).<br>Normally that is realized with two voltage regulators, a 7805 for the core and a 7812 for the sid module (SID 6581) which have to be driven by a higher voltage than their output is. (They need "headroom" to work, since they have a voltage drop. Anyway there is another drop over the recitifier diodes).

Now there are various options:

a) Using two dedicated PSU/ Wallwarts to drive two Vregs. One for the core and one for the SID Module. You could use a 7-10V wallwart for the core and a 15V wallwart for the SID. Depending on whether you use a LCD or not they should have sufficient current rating. (read the module description for more info).

b) Using one PSU / Wallwart that drives two Vregs. The more elegant option. 15V (AC or DC) is needed to drive both. 500mA min. current required. Take into account that the Vreg of the core is very likely going to be hot (it "burns" the voltage surplus) and needs a heatsink depending on the load (lcd or not).

c) using a C64 PSU (http://ucapps.de/mbhp/mbhp_sid_c64_psu.pdf)

d) Using one 12V DC regulated PSU with one Vreg. Drive the core module with a 7805 Vreg and drive the SID directly with the PSU. It must not fluctuate! Quality PSU needed :-)

Edited January 12, 2011 by phunk

[Starfire]

I can recommend the 12VDC regulated supply from all electronics it has ran my 6581s fine direct from the supply, puts out a nice constant 12VDC

My linkhttp://www.allelectronics.com/make-a-store/item/PS-1251/12-VDC-500-MA-REGULATED-POWER-SUPPLY//1.html

Edited January 13, 2011 by Starfire

[bleeptor]

Thanks a lot, my options are quite clear now. I think I'll go with 1 PSU with 2 Vreg, I'll see how it goes.

[bleeptor]

Hi! So I got my power supply, 15 VDC 800mA. I just sent 2 + voltages, one to the J1 port of the CORE, and one to the J1 port on the SID. I guessed the voltage regulators on the boards(from smashtv) would do the trick. I connected ground to the Vss of the CORE and to the J1 port of the CORE. So I got my CORE connected, checked the voltages and they read 4.97, so I guess that's fine. I got the ready message so I think everything's fine with the CORE. I connected the SID to the core and checked the voltages as I saw in one of the forums that somebody did it :

IC1 25 -> 14

IC2 8 -> 16

IC3 8 -> 26

So I checked without really knowing where to place the black and the red cables of my probe, so I put the red cable in pin 25 and black(COM) in pin 14. IC1 was getting 4.95 V. I checked IC2, with COM on pin 8 and red on pin 16, it reads 4.95 V. Then I don't know if this guy messed up or what, but the IC3 just has 16 pins. So I supposed he meant to check pin 8 and 16, so I did, black on pin 8 and red pin 16, and got 4.95 V.

So I just wanted to make sure I was getting everyhing right before I put the SID chip, because I don't wanna ruin the chip. I thought I was gonna get 12 V on the SID, that's why I'm wondering if everything's fine. I'll appreciate some guidance to get to place the SID chip and make the first noise finally!

[m00dawg]

Pins 28 and 14 would be what should give you 12V. There's some good documentation on what to do at this stage on ucapps.de, specifically: http://ucapps.de/mbhp_sid.html. The SID should get +5V from CORE and the +12V would be coming from it's own 7812. That is, if you're using a separate CORE and SID module.

You probably don't need to heatsink that for one SID (never hurts) but you'll want one for the 7805 off the CORE module almost for sure since it's having to "burn off" 10V or so from your 15V power supply. It burns it off as heat so, as you can imagine, that sucker can get hot and will shut down if it gets too hot, spoiling your awesome SID fun-time.

[Napalmtree]

Been looking for schematics for power supplies since I don't have the C64's and do have a 12V 500 mA DC wallwart. So for option D using the one Vreg on the core you simply jumper the Vreg spots on the SID modules to get the 12V correct? as far as the 5V coming in from the core to the SIDs where is this connection at? I have all the data lines and J14 connected like in the optimized C64 powered version. Just curious as to the purpose of the Vs and Vc holes as well as J2. Also, So far I have power going to the 3 PCBs J1's and the core Vreg is getting super hot as is, but not shutting off. Have you been using a heat sink for yours or is it maintaining well at high temps? The SID Vregs don't heat up in the slightest bit of course, but will jumper them anyhow. As is, my LCD is lit(it's http://www.mouser.com/Search/ProductDetail.aspx?R=UMSH-3267MD-UBvirtualkey66830000virtualkey668-UMSH-3267MD-UB ), but blank with a few characters popping up now and then and the only sound I get is a charging up and dispersing sound when I plug the DC jack in and out. If I get this sorted out I will definitely write up the alternative power schematic to post with the Midibox V2 setup less someone has a link i managed to overlook. Now for some pale ale and solder fumes. mnnnnn....

Edited April 19, 2012 by Napalmtree