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Does anybody know how to calculate this in an effects pedal?
- Thread starter Gutch220
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Applying schematic theory your AC input impedance would be:
Zin = 22K + 100K||100K||Beta x 1.8K
where || means resistance in parallel, Beta is DC gain of transistor (also known as hFE on datasheets).
Using min value for Beta of 250 from datasheet equation above reduces to:
Zin = 22K + 50K||450K
Zin = 22K + 45K
Zin = 67K
If you would like to practically measure the ac input resistance (Zin) then feed a 1khz 100mV signal into the pedal. Measure the input current. Zin = Vin/Iin.
You cant do this with a DC input as it will be blocked by the input blocking capacitor.
Zin = 22K + 100K||100K||Beta x 1.8K
where || means resistance in parallel, Beta is DC gain of transistor (also known as hFE on datasheets).
Using min value for Beta of 250 from datasheet equation above reduces to:
Zin = 22K + 50K||450K
Zin = 22K + 45K
Zin = 67K
If you would like to practically measure the ac input resistance (Zin) then feed a 1khz 100mV signal into the pedal. Measure the input current. Zin = Vin/Iin.
You cant do this with a DC input as it will be blocked by the input blocking capacitor.
67k sounds about right. I know it would likely be very low.
I don't own one to measure, or have a signal generator.
I think fuzz faces have it at about 10k +/-
This information, or actual measured value, seems impossible to find online.
I don't own one to measure, or have a signal generator.
I think fuzz faces have it at about 10k +/-
This information, or actual measured value, seems impossible to find online.
I love Super Fuzz pedals. Such a huge gnarly sound. I have a clone that I built and it’s pretty noisy, unfortunately. One day I’ll try to figure that out. It may just be the nature of the beast, though.
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