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EHX - OLD Low Frequency Compressor

Started by zombiesonore, January 18, 2015, 01:16:43 PM

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zombiesonore

Hello everybody,
a friend of mine give this very nice effect.
It works properly but only with battery and I would like to modify it and put a DC jack.
The problem is that I've trouble understanding the wiring and really what kind of current this effect needs.
It use 2 9V Battery and I don't know if it needs 18V or maybe bipolar 9V...
I was thinking using a "road rage" board but if it need bipolar supply, I don't know how to do it...
For info, the switch at the top is an on/off switch.
Can you help me?
Thanks,
Etienne 

Scruffie

It's bipolar, look at a charge pump datasheet and it'll show you how to do it or someone might have a suggestion for a ready made pump board.

Although... you sure you want to drill in to a vintage EHX pedal for DC?
Works at Lectric-FX

zombiesonore

Thanks Scruffie!
I made it works with the -9V and +9V output of the road rage.
QuoteAlthough... you sure you want to drill in to a vintage EHX pedal for DC?
You mean that it will loose $$$ value? How much do you think this effect could be sell?
Not that I'm about making money... Just for my knowledge...

Scruffie

Wait! Not sure it is bipolar, I have a schematic for a bipolar version and an 18V one.

Can you post a shot of circuit side of the board?

Value... check ebay completed listings, personally, I just think it's a shame to mod a vintage pedal that seems to be in quite good condition.
Works at Lectric-FX

zombiesonore


Scruffie

You're good, it's bipolar, phew! :D

Me and Keefe might do a PCB for this (I love EHX stuff so we will) if you wanted to keep it stock...
Works at Lectric-FX

zombiesonore

Yes, a PCB would be nice.
Like I've said, I tried to power it with a road rage and it worked, but I felt that the sound was weak...
So I will keep it like it was.
Thanks again.

TGP39

Good call. I'm with Scruffie on this one. These old EHX pedals are works of art. You wouldn't want to drill Mona Lisa would you?  Perhaps I could have worded that better!  ;D

Steve.
Follow me on Instagram under PharmerFx.