Scale resistance range?
Scale resistance range?
(OP)
Friend and I are trying to build a ribbon controller, like this one:
http://www.youtube.com/watch?v=rexNt0Tau_o
Our problem is this: Our ribbon runs a resistance of 50kOhm to 500kOhm from lowest end to highest end, and the Timer circuit will give an output time proportional to the RC value. With a gigantic R value, the output sound becomes very low frequency(3hz) and cannot be heard.
I cannot change the capacitor value, it is already the lowest we can find...
So we need a way to reduce resistance on the ribbon. We cannot simply put the ribbon in parallel with a small resistor, because then the ribbon becomes useless as all the current goes through the small resistance, and the effective range of resistance becomes 1k-1.1k, making the instrument a near monotone.
SO, question is this:
Is there a way we can SCALE the resistance on the ribbon, 500k-50k near linearly to a smaller value, say 10k-1k? Such method would help us tremendously.
THanks so much!
-Evan
http://www.youtube.com/watch?v=rexNt0Tau_o
Our problem is this: Our ribbon runs a resistance of 50kOhm to 500kOhm from lowest end to highest end, and the Timer circuit will give an output time proportional to the RC value. With a gigantic R value, the output sound becomes very low frequency(3hz) and cannot be heard.
I cannot change the capacitor value, it is already the lowest we can find...
So we need a way to reduce resistance on the ribbon. We cannot simply put the ribbon in parallel with a small resistor, because then the ribbon becomes useless as all the current goes through the small resistance, and the effective range of resistance becomes 1k-1.1k, making the instrument a near monotone.
SO, question is this:
Is there a way we can SCALE the resistance on the ribbon, 500k-50k near linearly to a smaller value, say 10k-1k? Such method would help us tremendously.
THanks so much!
-Evan





RE: Scale resistance range?
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If we learn from our mistakes I'm getting a great education!
RE: Scale resistance range?
Buy a foot of two conductor cable and use that for a capacitor. If the capacitance is now too low, use a longer cable.
It is difficult to determine exact circuit details from the video. Perhaps look for a different video.
Bill
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"Why not the best?"
Jimmy Carter
RE: Scale resistance range?
RE: Scale resistance range?
Easy!
----------------------------------
If we learn from our mistakes I'm getting a great education!