[sdiy] dual gate mosfets

[anthony]

----- Original Message ----- 
From: "RMC" <RMC at richardcraven.plus.com>

>> 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?
>
> You could make them into double balanced mixers, also known as ring 
> modulators. Or, tie both gates together and use them as standard mosfets 
> in anything you like.

Thanks. I was indeed thinking: well they use them as mixers in radio so some 
kind of modulator sure.

And the last point brings me to another query:
Can you use mosfets in place of jfets in circuits that specify jfets? I 
assume yes, but... It's the but that I don't really know. I think I have 
enough jfets right now but:

I had also thought that if I had an op-amp that I really liked but it didn't 
have a high enough input impedence I could just use a mosfet for a 
front-end. I don't mind if it's more trouble if I already have the stuff. 
And I have quite a few of these mosfets.

Another mosfet question: Can you use the mosfets in switching supplies in 
amplifier circuits? The datasheets usually always seem to say more or less 
this is just a switch. I like the numbers though. I still like a nice 2N3055 
any day though. Bipolar transistors are kind of like that sweet chubby 
ex-girlfriend that you end up with again.