I'm trying to put a Jfet stage as input to my 2w amp.
12vac > FWR > Filtercap > 7809 Regulator > Filtercap = 9vdc power, with noise-hum.
The transformer is 3'' away from any of the other irons [choke, PT / OT] and the 9vdc PS leads are fairly short to the circuit, the circuit has very short in/out wiring.
If I put a battery on as the PS the noise is ~eliminated.
Open to suggestions / conclusions or theoritecal hypothises, any more info that's needed I'd be glad to supply.
Somehow RG managed to fit it into the workhorse, not sure what the noise-deal is with this platform though.
Hi
1. an LM7809 needs and input voltage of at least 12 V DC
2. it needs a small film cap (0.1uF) at its output
3. you might try a small resistor (e.g. 1, 2.2 or 3.3 ohms) in the PS line before the output cap (this greatly cuts noise on the line). It'll drop your output voltage a little ( = amps x ohms, e.g. 100ma x 3.3 ohms =0.33V drop).
cheers