help identify a component on a microphone circuit

M

Mike247

New Member
Hi, I'm wondering if someone here could possibly help identify a component. I'm an accordion maker with at best basic knowledge of electronics and sometimes I build microphones in the accordions and concertinas, they are quite basic but have survived me well the last couple of years, they are basic electret capsules running on 48v phantom power.

I brought the PCBs and components from Akihabara electronics market in Tokyo and I'm down to my last one and was going to order the components here in Ireland and print the board but I have realized I'm missing one component.

there are 2 TO-92 packages on the board, I have one it's the "F308 BC182 C" the other is the one I'm missing, from what I remember when I ran some tests on the components it was PNP.

If anyone can figure out what is was or another TO-92 that would work in it's place or a few that might work ied be even just a point in the right direction to figuring it out.
 

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Ramussons said:
BC xxx: 161, 177, 178, 179, 212, 213, 214, 307, 327, 328, ......

Google for "PNP BC series" transistors.
Click to expand...
Hi Ramussons thanks for the response, I'll have a look at the BC series and see if they work, why do you think it's something from the SERIES? is there something about the circuit that makes you think it's from the BC ?
 
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Mike247 said:
Hi Ramussons thanks for the response, I'll have a look at the BC series and see if they work, why do you think it's something from the SERIES? is there something about the circuit that makes you think it's from the BC ?
Click to expand...
Transistors are only very rarely critical, you can use BC series to replace most small silicon devices.
 
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BC212 is the PNP complement to the BC182.

If you cant find that BC556 is a substitute for the BC212 and BC546 is a substitute for the BC182.

Edit: found a close schematic for your pcb and it is indeed a BC212 you need.
 
Last edited:
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This is the actual circuit, the only difference between this and the OP's is that R2 has been replaced by a trimpot.

The function of this circuit is to interface an electret mic to phantom powered balanced dynamic microphone systems.

 
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Other options:
2N4401 / 2N4403
2N3904 / 2N3906
2N2222 / 2N2219

The first time I saw stacked transistors handling balanced audio like that was in the audio system of the AVR-1 back in the 60's. Still works, although I'm surprised there is no gain in the circuit.

ak
 
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You don't need gain, it's already feeding a microphone input, and the output from an electret capsule is fairly high anyway.
 
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I know. But still, the better place for a little gain is at the front end of the cable. For all we know, that circuit could be driving 200 feet of single-braid, 90% coverage cable in a TV station with SCR light dimmers in the studios. Been there, done that. A gain of 5, or even 2, up front wouldn't hurt. The physical structure and the power system already are there, and they are the hard parts.

ak
 
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The gain is already there, in the electret capsule
 
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