Midibox PSU

[Mr modnaR]

well, what's an average LED? 10-20mA? that gives around 1-2A if all are on at once.

[Altitude]

I just measured my LED's (bright blue) and without a resistor they pull 120 mA (what i like to call 'flashlight mode') and with a 1k, which brings to acceptable brightness, 2.6 mA

Bear in mind that there is never a case where all the LEDs will be on at once

[Mr modnaR]

that's true, it'd be nice to allow some headroom i guess.

[NorthernLightX]

To revive this old thread: I recently got some requests to share the .BRD file of the PSU. It has been on my space since the beginning, there just was no link to it  ;D

So, If anyone wants to toy with it:

http://home.quicknet.nl/qn/prive/alex.span/midibox/MBHP_PSU.brd and

http://home.quicknet.nl/qn/prive/alex.span/midibox/MBHP_PSU.sch

I just re-read some comments about the PSU not working properly. I have it hooked up to my current MBSIDV2 setup (one CORE_V2 and SID_V2 - these are old style boards) and it works fine. I do want to measure the voltage drop in the resistors before I claim it to be a good design though, hope I'll be able to do that soon.

I find the PSU to be pretty quiet, audio-wise. I would like for someone to test it with good equipment though, and the only one I can think of is TK. So Thorsten: would you want to build and test this PSU? I would of course provide you with a free PCB.

[doc]

I find the PSU to be pretty quiet, audio-wise. I would like for someone to test it with good equipment though,

quiet, audiowise: This depends not only on the PSU, it also depends on the transformer and the wiring.

Test: There's not a lot that can be tested. If you want to test it, you just need to measure the ripple at the output(s). If you have a good digital multimeter you can measure the ripple yourself:

Switch your multimeter to AC (Yes: AC!) and measure at each output the (AC-)Voltage. The lower the value, the better is your PSU for audio purpose.

greets

Doc

[NorthernLightX]

quiet, audiowise: This depends not only on the PSU, it also depends on the transformer and the wiring.

Test: There's not a lot that can be tested. If you want to test it, you just need to measure the ripple at the output(s). If you have a good digital multimeter you can measure the ripple yourself:

Switch your multimeter to AC (Yes: AC!) and measure at each output the (AC-)Voltage. The lower the value, the better is your PSU for audio purpose.

greets

Doc

OK, thanks Doc! I'm going to test that tonight. I'm using a toroid transformer, which is the most "quiet" transformer type as far as I know.

Cheers,  Alex.

[Slorrin]

great work.  Maybe smash TV will sell boards for this?  hmmmm?!

[NorthernLightX]

Test: There's not a lot that can be tested. If you want to test it, you just need to measure the ripple at the output(s). If you have a good digital multimeter you can measure the ripple yourself:

Switch your multimeter to AC (Yes: AC!) and measure at each output the (AC-)Voltage. The lower the value, the better is your PSU for audio purpose.

greets

Doc

I finally took some time to test the PSU today. The AC ripple is 0.0mV on the 12v lines, and 0,1mV on the 9v and 5v lines, tested with an ABB M2005 multimeter. I think that's pretty good. I have no reference on how a C64 brick with optimized circuit performs and do not have a functioning specimen lying around, so if someone would be so kind to take some readings, that would be nice for comparing.

Cheers, Alex.

[edit]

Put most info in my user WIKI:

http://www.midibox.org/dokuwiki/northernlightx

IF this is found to be of use as a general MidiBox PSU it'll find it's way to the proper WIKI section(s).

[Shuriken]

I have a question about the diodes. As the choice for the 1N4008 seems a bit odd to me.

The 1N4008 is 1A only. Since the current draw is theoratically 3A (7812,7809 and 7805 combined) wouldn't it be more logical to choose the 1N5401 which is rated up to 3A?