[sdiy] dual gate mosfets

[James Patchell]

Dual gate mosfets had two primary uses.  In the RF amplifier, the second 
gate can be used to control the gain, and in the mixer, the second gate is 
used to modulate the in coming carrier with the local oscillator.  So, in 
therory, you could use a dual gate mosfet as a VCA, and as a 
MODULATOR.  This will be more or less AM modulation, rather than Balanced 
Modulation.  And I say more or less AM modulation because the gain control 
the second gate offers is not exactly linear.

Other possible uses would be as the frequency control in a voltage 
controlled filter...which could be interesting.

Also, a lot of the dual gate mosfets did not have any protection on their 
inputs....so use good anti static handling proceedures.

At 07:12 PM 1/22/2005 -0500, anthony wrote:

>I have a lot of dual gate mosfets that I've removed from old radio 
>equipment. Mostly 3SK45's and 3SK51's. Can anyone think of any synth uses 
>for them? Assuming of course that I didn't toast them.

         -Jim
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