I am building a guitar reverb pedal from some salvaged parts. From a
dead "Image" guitar amp, I got an itty bitty 5" reverb spring can and a
control pot with an attached circuit board about the size of a cracker
(the kind you eat). This circuit was wired in to the original amp's
circuit as an effects loop. Now the way I want to use it, with a guitar
plugged into the input and the output plugged into the input of an amp,
there was not enough volume, even with the amp cranked. I searched
through my parts/junk boxes and found a few transistors to use to
augment the existing circuit. I now have the thing working with a two
stage amplifier boosting the output of the reverb circuit. I used two
2N4124 transistors connected to the output of the reverb circuit board
with .068 coupling caps (happen to have a lot of those). Other
transistors I could have used are 2N4126 (PNP?), 2N5060 or a host of
others. The power supply is around 11 vdc, wall wart. I haven't
soldered anything yet, will be using a bit of perf board for the new
circuitry. Are these transistors a good choice for this application?

John Kogel

"Porky" wrote in message
ups.com...
I am building a guitar reverb pedal from some salvaged parts. From a
dead "Image" guitar amp, I got an itty bitty 5" reverb spring can and a
control pot with an attached circuit board about the size of a cracker
(the kind you eat). This circuit was wired in to the original amp's
circuit as an effects loop. Now the way I want to use it, with a guitar
plugged into the input and the output plugged into the input of an amp,
there was not enough volume, even with the amp cranked. I searched
through my parts/junk boxes and found a few transistors to use to
augment the existing circuit. I now have the thing working with a two
stage amplifier boosting the output of the reverb circuit. I used two
2N4124 transistors connected to the output of the reverb circuit board
with .068 coupling caps (happen to have a lot of those). Other
transistors I could have used are 2N4126 (PNP?), 2N5060 or a host of
others. The power supply is around 11 vdc, wall wart. I haven't
soldered anything yet, will be using a bit of perf board for the new
circuitry. Are these transistors a good choice for this application?

John Kogel


Does it sound good to you? When it comes to guitar amps that's the important
factor, it may be a horrible amp by looking at the numbers, but if it has
the sound you want then go for it.

Personally I'd use an op-amp rather than making the amp from transistors but
again if it works and you've got it built you may as well go for it.

I guess it sounds ok, with nothing better to ref it to. I've shied away
from op amps for 2 reasons. I don't have a schematic to follow and
don't know the pinouts on any of the chips I've got here. Number 2, you
need either a prefabbed drilled circuit board or a socket to mount them
in. So when you say looking at the numbers, are you referring to these
specific transistors as being horrible amps, cuz that's my question.

JK

In article .com,
Porky wrote:
I've shied away from op amps for 2 reasons. I don't have a schematic to
follow and don't know the pinouts on any of the chips I've got here.

Any hobby electronics book will give you all these. And most op-amps use
the same basic pin out for supply, inputs and output.

Number 2, you need either a prefabbed drilled circuit board or a socket
to mount them in.

They fit direct to veroboard.

--
*Never put off until tomorrow what you can avoid altogether *

Dave Plowman London SW
To e-mail, change noise into sound.

Ok, I will check into that. Why then is an op amp a better choice,
other than fewer connections involved, which is not a major issue. I
like solder.

In article .com,
Porky wrote:
Ok, I will check into that. Why then is an op amp a better choice,
other than fewer connections involved, which is not a major issue. I
like solder.

It's an instant audio solution with a high input impedance and pretty low
out. Easy to set the gain and tailor the response.

--
*Isn't it a bit unnerving that doctors call what they do "practice?"

Dave Plowman London SW
To e-mail, change noise into sound.

"Porky" wrote in message
oups.com...
Ok, I will check into that. Why then is an op amp a better choice,
other than fewer connections involved, which is not a major issue. I
like solder.


Op-amps are just much nicer to work with, it's a one chip solution and very
versatile. There's TONS of info out there on using them, here's a page for
example http://www.northcountryradio.com/PDFs/column003.pdf