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Old 2nd December 2010, 12:05 PM   #1
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Default Complementary to BC115

Is there a PNP version to the BC115 NPN transistor? Thanks.
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Old 2nd December 2010, 12:38 PM   #2
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I guess I suspect that no-one manufactured a PNP version of the BC115.

In a non Hi Fi application, (modulator amplifier service for transmitter, not Hi Fi) which is the case here, can anyone please suggest what would be reasonable PNP replacement for BC115? Circuit works off 12V.

In fact, the circuit is here, where I might want to change 15VT1:

http://homepage.ntlworld.com/richard...Y/circuit.html

Last edited by richard8976; 2nd December 2010 at 12:40 PM.
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Old 2nd December 2010, 04:50 PM   #3
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I'm a right stickler for drawing circuits that make it easy. I always "want" to see emitters of transistors that are in a Common Emitter arrangement, on the same side as, or pointing to ground!

I should really stick with the BC115, just show emitter towards ground.

15VT1 on the original circuit just bugs me with it's emitter pointing up the schematic!

(BTW, I am on pills for this condition).

Last edited by richard8976; 2nd December 2010 at 04:53 PM.
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Old 2nd December 2010, 05:34 PM   #4
wahab is offline wahab  Algeria
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As a replacement, BC107, 546, 547 or 550 should do it..
As PNP complementaries, BC177, 556, 557 and 560 respectively.
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Old 3rd December 2010, 04:38 AM   #5
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Yes, nothing of BC115 is particular except no complement, only low gain, low dissipation and Ft 80mHz.

As an audio driver, you might look to more modern high voltage types (BC546/56 as listed by Wahab or 2n5401/5551 etc.) in an effort to limit Hfe to original part spec, if there is a stability issue in your application.

Something non-RF guys often neglect is the sensitivity of audio circuits to RF. High gain/Ft audio parts where they are not strictly needed can cause mayhem and QRP transmitters, for example, are notorious for such problems where RF and AF circuits are in close proximity and poorly shielded IME.
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Last edited by Ian Finch; 3rd December 2010 at 04:43 AM.
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Old 3rd December 2010, 05:07 AM   #6
CBS240 is offline CBS240  United States
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What is the purpose? I'm sure there are other devices that will suffice for the purpose.
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Old 4th December 2010, 02:31 PM   #7
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Quote:
Originally Posted by wahab View Post
As a replacement, BC107, 546, 547 or 550 should do it..
As PNP complementaries, BC177, 556, 557 and 560 respectively.

Thanks. Rich
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Old 4th December 2010, 03:48 PM   #8
jaycee is offline jaycee  United Kingdom
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The circuit you are looking at is for Germanium transistors, which is why most of them are PNP and the powersupply is -24V with respect to ground. This was typical of Ge-based transistor circuits. Similarly the transformer coupling is a sign of Valve type design, with Ge transistors substituted.

What does the circuit actually do? It looks like some kind of microphone amplifier.
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Old 4th December 2010, 03:52 PM   #9
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Quote:
Originally Posted by jaycee View Post
The circuit you are looking at is for Germanium transistors, which is why most of them are PNP and the powersupply is -24V with respect to ground. This was typical of Ge-based transistor circuits. Similarly the transformer coupling is a sign of Valve type design, with Ge transistors substituted.

What does the circuit actually do? It looks like some kind of microphone amplifier.
It's a modulator. Well, an audio amplifier, that is used to modulate an RF carrier.

Audio quality will be naff by comparison to Hi Fi, but satisfactory for voice communications.
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