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and again, help please.

5/30/1999 7:07 PM
John C.
and again, help please.
mods: (doubts about uses for DPDT's switches)  
I have a circuit, and I want to mod part of it without  
having to rebuil it all, so I have two versions in the same box.  
Both ends of the original, and the moded part stay  
connectet to the same part of the circuit where they have to,  
BUT the beginings are introduced in the circuit  
with a switch (part a, or part b) Please remember  
that both ends of both versions will allways stay  
connected to the main board, ONLY the beginings  
are one or the other, on or off.  
Question (big doubt):  
Would, having it mounted like that, the part of the  
"out of the board" circuit that stays off at the momment, but with  
one of it's "ends" connected to the main circuit board,  
interfere with the rest of the effect?  
Short explanation. In a circuit, I want to mod part of the circuit,  
which consists in a FET (pin D -->to 9v, so it will allways be receiving  
power even the one (FET) that is in the unconnected part or version...) and a couple  
of caps and resistors that are all of them interconnected, that is,  
one right after another,  
so I though I might cut the circuit at the begining of that part,  
build a small board appart with those "option B" components, and with a DPDT,  
introduce the "original" or the moded.  
But to do that, the "ends" of both versions, the "original" and the moded board, have to  
be always conected to where they belong in the main circuit.  
Important: the transistor is connected to the 9v line even if it belongs to the "unconnected-in-one-of-it's-ends part of the circuit".  
Sorry, I had too...  
(I'll try by myself anyway)  
5/31/1999 7:05 AM

If you can sketch up what you have I might be able to help.  
In general, the inputs of things are higher impedance (that is, can suck less electrical current) than the outputs of things. That means that you can usually parallel the inputs of things, just connect them together with wires, and they won't interefere. You usually can't parallel the outputs of things and have them not interfere because they "fight" to put out the current that they "think" should be there, and this is often not what you had in mind.  
If I understand some of what you're doing, I would parallel the inputs of the two sections and switch the two outputs.  
But I'm having a hard time following the description - must be too early in the morning, or not enough coffee ;-)
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5/31/1999 7:20 PM
John C.

Thanks again R.G.  
>But I'm having a hard time following the description - must be too early in the  
morning, or not enough coffee ;-)  
I'm afraid it's my fault.  
It's all about the ProCo Rat circuit you once draw.  
I'm finishing the "original", and besides  
that couple of Ge or Si clipping diodes I could introduce separately via some sort of SPST switche, the rest of the modified circuit begins just after a 100k pot right to a 0.022uF cap`.  
So I thought I could "cut" right after the pot and right before de cap, and "introduce" the other modified version with a DPDT, but to do that (after a lot of thinking...) I realized that one of the "ends" of the moded subcircuit has to stay connected to the main board, that is, or the point at the pot, ot the point at the cap.  
One "channel" of the DPDT will handle R1 ON, R1 OFF. The other "channel" will do the same with the LED RAT modified part of the circuit,  
and I could even "generate" the Turbo Rat while the Led RAT is on, by switchig sepparately the two Si diodes instead of the Ge ones.  
If this can be done, wich "end" of the sepparate little board would be saver to remain always connected to the main board, the pot end or the cap end??  
If it is too much thinking, I'll just build a second pedal with the hole Led RAT, and generate the Turbo RAT by the "trick" of the SPST diode couple switching.  
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