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DIY Stompboxes => Building your own stompbox => Topic started by: loki on July 30, 2004, 01:54:17 PM

Title: strange thing happened
Post by: loki on July 30, 2004, 01:54:17 PM
just today i finished putting together a CA's Volume Pedal De-scratcher, after a first failed attempt...
so i connected it to my volume pedal and it worked... it's just that it adds a little gain when the pedal is fully rocked forward if compared to the straight sound, good for guitar i guess... not too much for my bass though....but i guess it's normal since i've read build reports by others which stated the same thing...
but anyway... i was about to change the TL071 with a NE5534, just for a test... everything was still connected and the amp on, so as i pulled the TL071 out of the socket, the circuit kept working!  :o  :o with a slight gain decrease, which still distorts the signal a bit, but not as much as when the TL071 was on....
could someone explain that?  :? is it possible that the circuit just keeps working without an opamp?

and by the way the prob i have is that i'm powering it with a power supply, but i can't screw the DC jack (metal) to the pedal enclosure, because it shorts.... how can i do to isolate it?
thanks
bye!
Title: Re: strange thing happened
Post by: casey on July 30, 2004, 02:57:13 PM
Quote from: lokijust today i finished putting together a CA's Volume Pedal De-scratcher, after a first failed attempt...
so i connected it to my volume pedal and it worked... it's just that it adds a little gain when the pedal is fully rocked forward if compared to the straight sound, good for guitar i guess... not too much for my bass though....but i guess it's normal since i've read build reports by others which stated the same thing...
but anyway... i was about to change the TL071 with a NE5534, just for a test... everything was still connected and the amp on, so as i pulled the TL071 out of the socket, the circuit kept working!  :o  :o with a slight gain decrease, which still distorts the signal a bit, but not as much as when the TL071 was on....
could someone explain that?  :? is it possible that the circuit just keeps working without an opamp?

and by the way the prob i have is that i'm powering it with a power supply, but i can't screw the DC jack (metal) to the pedal enclosure, because it shorts.... how can i do to isolate it?
thanks
bye!

ok, im not for sure about pulling an opamp out and it still work...
that's a little strange....

but as far as the d.c. jack.....steve daniels over at smallbear had an
excellent article about how to do that...  you basically drill a larger
hole than what is needed for the jack...then you fill that hole in with
bondo...sand it down smooth once dried.  then redrill for the jack.
the jack is then surrounded by non-conductive bondo....  bingo...youre
done.
Title: strange thing happened
Post by: loki on July 30, 2004, 06:31:17 PM
it's strange indeed... but i can tell you the thing works, i currently use it without one of the 2 opamps mounted and i have no problems  :?
anyway thanks for the tip about the dc jack. now i just need to find some bondo :)
Title: strange thing happened
Post by: Ge_Whiz on July 30, 2004, 07:00:12 PM
I dunno what this circuit consists of, but if it's just an op-amp buffer of some kind, there is usually a signal route from input to output via an op-amp feedback resistor, even in the absence of battery, op-amp, whatever.
Title: strange thing happened
Post by: mugan on July 30, 2004, 08:15:27 PM
for the dc jack i suggest to change it with a plastic one, less work, better result...