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Hoffman Amps Forum image Author Topic: Lost tread - there was a tread about a simply mod with a FS and a resistor .....  (Read 2197 times)

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Offline kagliostro

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I'm looking for an old tread where it was discussed a simple mod where (if I remember correctly) a Foot Switch was used to short a resistor

that was on the preamp section (after V1 ??) giving a Boost effect, it was something related to a partition resistor between V1 and V2
(or so seems to me)

May be SILVERGUN posted a schematic or a link to this feature but I'm not able to find the tread

can someone give me help ?

Thanks

K
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Offline MakerDP

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I'm not familiar with the thread but if you had a typical 470k/470k voltage divider between two gain stages you could have a foot-switchable resistor in parallel with the "R1" series resistor of the divider (the one NOT going to ground.)

For example, 1v of input on the typical 470k/470k divider would yield 0.5v output
Parallel a 470k on top of the "R1" 470k to get a 235k/470k divider yielding 0.67v output -- a nice little boost.

Tweak that paralleled resistor to taste.

Is that what he was doing?

Offline kagliostro

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Ciao MakerDP

thinking about the circuit surely it will be something as you say

but I have interest also to re-read the tread

anyway many thanks for the answer

Franco
« Last Edit: May 15, 2015, 11:36:50 am by kagliostro »
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Offline chocopower

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I think a better way is using 2 resistors in serie to ground.


This way you can use an standard footswitch without relay.


You can put a pot wired as variable resistor so you can dial the boost level






             
David

Offline chocopower

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I think a better way is using 2 resistors in serie to ground.


This way you can use an standard footswitch without relay.


You can put a pot wired as variable resistor so you can dial the boost level

David

Offline kagliostro

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Many Thanks Chocopower !

---

I've just find the old tread I was looking for :grin: :grin:

http://el34world.com/Forum/index.php?topic=15080.msg144992#msg144992



Franco
The world is a nice place if there is health and there are friends

 


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