Maker Pro
Maker Pro

AM modulator

E

exxos

Jan 1, 1970
0
Hi all,

Im trying ot build a very simple AM modulator with a small op-amp, bascially
the carrier is fed into the amp input (as normal audio) then im using a
transistor to alter the other input side in attempt to alter the volume, I
can't however for the life of me get it to work.... I've also tried a
resistor in the carrier line, then pulling the output side of the resistor
down to ground with the modulation wave, this to me should work though no
matter what I do it just dont seem to work at all :(

has anyone got any simple solutions to this ?

thanks
 
R

R. Steve Walz

Jan 1, 1970
0
exxos said:
Hi all,

Im trying ot build a very simple AM modulator with a small op-amp, bascially
the carrier is fed into the amp input (as normal audio) then im using a
transistor to alter the other input side in attempt to alter the volume, I
can't however for the life of me get it to work.... I've also tried a
resistor in the carrier line, then pulling the output side of the resistor
down to ground with the modulation wave, this to me should work though no
matter what I do it just dont seem to work at all :(

has anyone got any simple solutions to this ?

thanks
 
E

exxos

Jan 1, 1970
0
thanks everyone, ive got some ideas of more things to try now,

chris
 
J

john jardine

Jan 1, 1970
0
exxos said:
Hi all,

Im trying ot build a very simple AM modulator with a small op-amp, bascially
the carrier is fed into the amp input (as normal audio) then im using a
transistor to alter the other input side in attempt to alter the volume, I
can't however for the life of me get it to work.... I've also tried a
resistor in the carrier line, then pulling the output side of the resistor
down to ground with the modulation wave, this to me should work though no
matter what I do it just dont seem to work at all :(

has anyone got any simple solutions to this ?

thanks
This modulator circuit is very simple. As the gain control voltage is varied
from 10V to 0.5V the gain drops from 100X to nothing. (Pretty much any small
signal transistor will work).

Gain Control
.-----o 0.5 to 10V
|
.-.
| |
2k2| |
'-'
Audio In ___ | ||
(say 10mVpp) .-|___|------o---||----o Audio out
| 470k | || 0 to 1Vpp
|| ___ | |/ 47uF
o-||--|___|----o----------|
|| 1k BC546 |> o
o 47uF | |
| | |
'---------------------------|---------'
===
GND

(created by AACircuit v1.28 beta 10/06/04 www.tech-chat.de)
 
Top