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power supply delay: success !

2007-05-12 by Scott Juskiw

I've recently added Ken Stone's CGS63 power supply delay board to one of my MOTM synth cabinets. I'm happy to report that it has completely cured the startup problems I was having with that cabinet. I will be adding the CGS63 to all remaining cabinets and can highly recommend it to anyone else who is having power supply startup issues.

I'm posting this message to the MOTM list because I've had a few MOTM users ask me for a parts list.

Note that the CGS63 will accommodate +/-15V alone, or +/-15V and +5V. I built the full circuit with support for +/-15V and +5V. Here is a Mouser parts list for the full circuit:

Quantity Mouser# Desc.
1 512-1N4002 1N4002 diode
1 512-BC338 NPN transistor
1 511-UA741CN 741 op-amp
8 571-6404456 MTA-156 6-pin header
2 653-G6A-274P-DC12 12V relay
1 72-T20YP-500K 500K trimmer
1 291-47K-RC 47 kohm resistor
1 291-10K-RC 10 kohm resistor
1 291-1M-RC 1 Mohm resistor
1 291-100-RC 100 ohm resistor (RCO on CGS63)
1 140-XRL25V1.0-RC 1 uF capacitor

If you don't need +5V at all, and you're sure you never will, then use this Mouser parts list:

Quantity Mouser# Desc.
1 512-1N4002 1N4002 diode
1 512-BC338 NPN transistor
1 511-UA741CN 741 op-amp
8 571-6404454 MTA-156 4-pin header
1 653-G6A-274P-DC12 12V relay
1 72-T20YP-500K 500K trimmer
1 291-47K-RC 47 kohm resistor
1 291-10K-RC 10 kohm resistor
1 291-1M-RC 1 Mohm resistor
1 291-200-RC 200 ohm resistor (RCO on CGS63)
1 140-XRL25V1.0-RC 1 uF capacitor

It is possible to add the +5V support later, but it would be a pain to upgrade, so make sure you make the right choice.

For some reason, the 100K trimmer is "obsolete" at Mouser. You can use any trimmer from 50K to 1M. I've listed the part number for a 500K trimmer, which is what I used.


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