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Video circuit amplifier

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kkdelabaca

kkdelabaca

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hello,

What does this circuit? The control voltage is from 0 volt to -8 Volt. The source of the transistor is connected to GND.

The gain of the amplifier is about 14, but what is the function of the JFET? I think that the circuit is an amplifier controlled by the PIN control. Anybody can confirm? What is the reason for having two transistors in parallel?

**broken link removed**

Thanks!
 

This looks like a standard opamp-based amplifier with adjustable input level ..
The adjustmat is achieved by varying resistance of JFET(s) and connecting two in parallel may mean that the ON resistance of one JFET is to high to sufficiently attenuate the input level at its lower end, and if another one is added the input signal can be reduced down to a tolerable level ..

Regards,
IanP
 

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