Secret Diagram

With this circuit we can amplification selectively the high signal of picture frequencies [Video] with result bigger clarity than this. The circuit should be placed between a Video unit and the reception Scart or the plug Video input of television receiver. The designing is simple, it’s based in three only transistor.

Video Signal Emphasis Circuit Diagram


The first stage of Q1 function as isolator - adapter of input impedance. The second stage round the 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.

Part List

R1=82ohm
R2=5.6Kohm
R3-9-11=2.7Kohm
R4=330ohm
R5=220ohm
R6=470ohm
R7=270ohm
R8=12Kohm
 R10=2.2Kohm
R12=180ohm
R13=68ohm
C1-4-5=100uF 16V
C2=2200uF 16V
C3=470pF ceramic
C6=470uF 16V
C7=220uF 16V
C8=100nF 100V MKT
TR1=250ohm trimmer
TR2=500ohm trimmer
D1=1N4148
Q1-2-3=BC547
J1-2=Female RCA jack
J3=2pin connector 2.54mm step

Video Signal Emphasis PCB