inklen
Full Member level 1
Hey guys!
This is my first circuit I build, so please bear with me.
I made a prototype for a dynamic mic amplifier on a transistor and LM386 which contains a transformer and 4 electrolytic capacitors (and some others for bypassing and filter - 1n , 100n). Electrolytic ones are 100 uF and 220 uF 16V. The source voltage is 9V.
The prototype works, so I made a PCB for SMD components. It came out very good. But when I soldered everything I had smoke somewhere in the capacitors area I double checked the circuit and found a bug in my PCB. So I made it again. And I had smoke again... I figured I used wrong voltage capacitors - 6.3V instead of 16V (Vs=9V). I didn't have 16V capacitors but I had 10V tantalum ones (instead of electrolytic), so I used those. I made another PCB with them and the circuit worked for ~1 minute... and then I started hearing either clicks or noise. I desoldered the transistor and checked - it does work (used transistor tester for this). I checked capacitors - all seem to have their capacitance values. I have no idea how to check LM386, so I removed it and put a new one. Same result - still clicks or noise, or something in between.
So I'd really appreciate some ideas (and probably knowledge from experience) on how to fix or make it right.
One thing to keep in mind is that it never worked again (after those initial 2 minutes), no matter what I do.
My only idea for now is to really put 16V capacitors (ordered already).
Thanks in advance!
This is my first circuit I build, so please bear with me.
I made a prototype for a dynamic mic amplifier on a transistor and LM386 which contains a transformer and 4 electrolytic capacitors (and some others for bypassing and filter - 1n , 100n). Electrolytic ones are 100 uF and 220 uF 16V. The source voltage is 9V.
The prototype works, so I made a PCB for SMD components. It came out very good. But when I soldered everything I had smoke somewhere in the capacitors area I double checked the circuit and found a bug in my PCB. So I made it again. And I had smoke again... I figured I used wrong voltage capacitors - 6.3V instead of 16V (Vs=9V). I didn't have 16V capacitors but I had 10V tantalum ones (instead of electrolytic), so I used those. I made another PCB with them and the circuit worked for ~1 minute... and then I started hearing either clicks or noise. I desoldered the transistor and checked - it does work (used transistor tester for this). I checked capacitors - all seem to have their capacitance values. I have no idea how to check LM386, so I removed it and put a new one. Same result - still clicks or noise, or something in between.
So I'd really appreciate some ideas (and probably knowledge from experience) on how to fix or make it right.
One thing to keep in mind is that it never worked again (after those initial 2 minutes), no matter what I do.
My only idea for now is to really put 16V capacitors (ordered already).
Thanks in advance!