lolo-m
Well-known member
I think this can be interresting for a lot of poeple here... The Fairchild is fascinating a lot of poeple, and there are a lot of nebulous points on it's basic operating principle...
It's also a way to check if I understood correctly ...
On the drawing down there :
1 - the SC amp input tranformer symetrises the signal
2 - each 12AX7 triode is mis-biased in the first stage so they amplify only the over modulation. The operating point of the triodes is set by a mono pot, and the dual pot (threshold) set the amount of signal we want to go into the SC amp.
3 - each side of the amp amplify it's part of the over modulated signal to get the voltage and power needed for charging the TC network.
4 - The SC-amp output transformer substracts the two signals ( signal A - signal B )
5 (not shown) - The diode bridge after the transformer rectify the wave into DC to charge the TC network
It's also a way to check if I understood correctly ...
On the drawing down there :
1 - the SC amp input tranformer symetrises the signal
2 - each 12AX7 triode is mis-biased in the first stage so they amplify only the over modulation. The operating point of the triodes is set by a mono pot, and the dual pot (threshold) set the amount of signal we want to go into the SC amp.
3 - each side of the amp amplify it's part of the over modulated signal to get the voltage and power needed for charging the TC network.
4 - The SC-amp output transformer substracts the two signals ( signal A - signal B )
5 (not shown) - The diode bridge after the transformer rectify the wave into DC to charge the TC network