| Electronics > Beginners |
| how to isloate audio ground from the amplifier |
| << < (13/14) > >> |
| Audioguru:
When you measure the resistance of the transistor in the circuit then you are measuring the resistance of the circuit, not the transistor. Since the emitter of the transistor has a resistor of 330k to ground then the transistor would measure 3.3k or less for it to make it emitter near +12V. Disconnect one end of the 100 ohm resistor to see if the pin 5 of the LM3915 or the transistor is shorted to +12V. |
| Adhith:
--- Quote from: Audioguru on May 20, 2018, 09:19:17 pm ---Disconnect one end of the 100 ohm resistor to see if the pin 5 of the LM3915 or the transistor is shorted to +12V. --- End quote --- Done it but there is no shorting. and the traces are perfect Seems like I founded out the problem Since there is no way of shorting I concluded that it may be the transistor and removed it. To my surprise I founded out that the transistor is not manufactured in the actual standard. During the diode test it is found that the base and collector are switched between each other. I never had encountered this type of problem and totally feel stupid. So this is the problem right?? I'm very sorry to waste your time upon this ridiculous thing. |
| Audioguru:
That is what happens when you buy a cheap fake Chinese transistor from ebay, Amazon or Ali. Oriental little transistors like a 2SC945 have the collector pin in the middle. A 2N3904 transistor is American. |
| Adhith:
--- Quote from: Audioguru on May 21, 2018, 05:46:48 pm ---That is what happens when you buy a cheap fake Chinese transistor from ebay, Amazon or Ali. Oriental little transistors like a 2SC945 have the collector pin in the middle. A 2N3904 transistor is American. --- End quote --- Yup I understood Sir. The transistor was bought from a local supply. I have bought a lot of 2N3904 from the same shop but never had any problem with it. previously you have also warned me about the fake LI ion batteries from china in this same discussion itself. I have taken it seriously from that moment onwards . But I never thought that the fake ones will change the standard pin configuration itself, that's totally unfair. The thing is that I didn't knew it was fake. I'll be more careful next time |
| Adhith:
The transistor has been replaced and the circuit works great. It has good response and the LM3915 barely heats up. I sincerely thank each and every person who helped me with this discussion. Special Thanks to Audioguru for supporting me till the end. |
| Navigation |
| Message Index |
| Next page |
| Previous page |