catfarm said:
Its an audio modulator. It uses 2x quad opamps (TL074) and some LED/CDs
pairs to modify the sound.
Interestingly enough when I pull the chips I read a nice 9V at the plug.
Putting in one chip drops the voltage to 3.7V. Bad chip? They aren't
getting warm when the circuit is running.
Im using a 9V source that comes from a 7809 and should be able to put out
500mA.
One thing you might try is removing the op amp and putting a resistor
across the 7809 output which simulates the load. Start with a 100 ohm,
1 watt or greater resistor and see what happens. Also, thake a look at
what's happening at the input voltage of the 7809.
I'm assuming you've got the pinout of the 7809 right. That's another
common newbie problem. If you've got a TO-220 package (square black
plastic with metal tab), holding the plastic side forward and pins
down, the pinout from left to right is
INPUT -- GND -- OUTPUT
Good luck
Chris
Good luck
Chris