| With this circuit we can amplify
selectively the high signal of picture frequencies [Video]. The circuit
should be placed between a Video unit and the reception of the plug Video
input of television receiver. The designing is simple, it's based on only 3
transistors. The first stage of Q1 functions as isolator - adapter of input
impedance. The second stage Q2 in common base connection which the gain is
determined by the TR2. The TR1, R6 and C3 determine the frequency response.
The third stage round the Q3 works as output buffer and 75-ohm line driver.
The TR2 should be regulated in a place where the circuit output voltage, to
be 1Vp-p, in 75 ohm load. The circuit functions with 12Volts - 50mA well
stabilized. the BC547 can be purchased from mouser electronics
www.mouser.com for 24 cents. |
