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DIY Stompboxes => Building your own stompbox => Topic started by: bwanasonic on January 27, 2005, 12:56:13 PM

Title: AMZ Mosfet Boost Output Impedance?
Post by: bwanasonic on January 27, 2005, 12:56:13 PM
Jack's Mosfet Boost article mentions that the output impedance is "moderately low" . How low is it? What variables effect it?

Thanks
Kerry M
Title: AMZ Mosfet Boost Output Impedance?
Post by: R.G. on January 27, 2005, 02:12:30 PM
The output impedance of any bipolar or FET common emitter/source amplifier is about equal to the collector/drain resistor. The collector/drain itself is quite high impedance, megohms, and so it hardly lowers the impedance of the resistor at all.

In all mos fet boosters like this, it's effectively the drain resistor, so 2.7K on this one.
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