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SPEECH PREAMPLIFIER COMPRESSOR

 

Component List
     
Resistors   Capacitors
R1= trimmer 500 K   C1= 2.5 Mf 16v elect.
R2= 100 K.   C2= 100 Pf
R3= 1 M.   C3, C5, C11= 5 Mf. 64v elect.
R4= 2,2 M.   C4= 100.000 Pf.
R5= 27 K.   C6= 47.000 Pf.
R6= 120 K.   C7= 27 Pf.
R7= 47 Ohm.   C8= 1 Mf. 40v elect.
R8= 47 K.   C9= 4,7 Mf 16v elect.
R9= 2,2 M.   C10= 100.000 Pf.
R10= 270 Ohm.    
R11= trimmer 100 K.   Transistors
R12= 22 K   TR1= 2N3820
R13= trimmer 50 K.   TR2 TR3= 2N1711 MC140
R14= 100 K    
R15= 470 K   Diodes
R16= Pot. lin. 50 K.   D1 D2= 1N914 1N4148
     
    ICs
    IC1= LM387


This preamp has high gain, but should have a flat response 300-3K..

73 De John, G8MNY @ GB7CIP
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