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1978 Deluxe big muff power supply issues and bipolar question

Started by LaceSensor, August 21, 2024, 09:01:19 PM

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LaceSensor

Hey everyone

I recently acquired a 78 IC deluxe big muff - the first version with the blend switch
Schematic is here https://postimg.cc/F7LVjGz1

It came with a 110v transformer and plug, and Im in the 240v UK
So I took an EHX transformer from another 70s pedal I have (Clone Theory) and wired it up.
Pedal works as it should, to the best of my knowledge

Two issues however.
1 - ideally I want to get rid of the noisy transformer
2 - its getting quite hot in operation and Im not sure thats normal / risky. Not too hot to touch but very warm
3 - the pedal uses a wierd power supply set up with a rectifier diode, and Ne5554n regulator chip

The power requiremens are basically bipolar +5v and -5v

I am wondering however if its possible to run it just off +9v and ground?
Alternatively, does anyone have a nifty circuit to make +5v and -5v like a RoadRage but different??

Thanks for the help!

Ian

LaceSensor

Had a think about this. I imagine just a charge pump LT1054 inverting to -9v and then a 337 adjusted to -5v
Then from the 9v input a standard 5v regulator 78L05 should do the trick

RoadDawg

You beat me to it... that's pretty much it, except why not use a 79L05 for the -5v.  So you would have +9v >> Road Rage or other CP circuit for +9v/-9v >> +5v/-5v regulators.

madbean

Or, just regulate the 9 to 5 before the inverter. +/-5 out.

mauman

I'd remove the AC input, transformer, bridge and regulator, and replace all that with a +9V DC input and a Traco TEC 2-0921 DC/DC converter.

LaceSensor

Quote from: madbean on August 21, 2024, 10:42:12 PMOr, just regulate the 9 to 5 before the inverter. +/-5 out.

Learnt something new today. That would have saved me some parts :)