R
Rikard Bosnjakovic
- Jan 1, 1970
- 0
Greetings
I found and built this project:
http://raymondaudio.nl/projects/project7/project7.html
After I finished and tested it out, I found lots of noise in the
headphones. Since my skill of analog electronics is way too low to get a
good guess what might have gone wrong, I took the construction to my
lecturer at the university. He gave me a couple of advices how to find the
errors in such piece of circuit.
Another week passed and after extensive searches, I think I have pinned
the problem. Here's an explanation of what I did to test and pin:
The blocks of the circuit are transformer, rectifier, linear regulators,
sound amplification. Using it plainly, I get lots of noise in the
headamps. Bypassing the transformer and rectifier-bridge (using a DC-psu
and feed the DC into the regulators), the noise goes away. Doing the same
but feeding to the bridge (i.e. "rectifying" my DC), the noise comes back.
I take this means the rectifier bridge (four 1N4005) is broken in some
way, but how? Before building, I tested each diode with an ohmmeter, and
they all showed "infinite" resistance in the wrong direction, and low
resistance in the correct direction.
So, what might it be that's happening at the diodes? Magnetic field
inducing? Short circuits?
I found and built this project:
http://raymondaudio.nl/projects/project7/project7.html
After I finished and tested it out, I found lots of noise in the
headphones. Since my skill of analog electronics is way too low to get a
good guess what might have gone wrong, I took the construction to my
lecturer at the university. He gave me a couple of advices how to find the
errors in such piece of circuit.
Another week passed and after extensive searches, I think I have pinned
the problem. Here's an explanation of what I did to test and pin:
The blocks of the circuit are transformer, rectifier, linear regulators,
sound amplification. Using it plainly, I get lots of noise in the
headamps. Bypassing the transformer and rectifier-bridge (using a DC-psu
and feed the DC into the regulators), the noise goes away. Doing the same
but feeding to the bridge (i.e. "rectifying" my DC), the noise comes back.
I take this means the rectifier bridge (four 1N4005) is broken in some
way, but how? Before building, I tested each diode with an ohmmeter, and
they all showed "infinite" resistance in the wrong direction, and low
resistance in the correct direction.
So, what might it be that's happening at the diodes? Magnetic field
inducing? Short circuits?