recently i found an old pcb containing germanium transistors that i decided to desolder, the transistors are a pair of: MP40 and MP39 as well as more MP40's, MP35 and MP37, im intrested if i could make an amplifier with these, probably tranformer coupled due to "low"(150ma) collector current.
also if it will be a transformer coupled design where could i find a transformer for these?.
also if it will be a transformer coupled design where could i find a transformer for these?.
Russian transistors by the look of it, If you need a transformer go find some old tape recorder or portable radio on the junk heat, you will most likely find a transformer.
An example germanium transistor power amplifier:
If you need the likes of T1 (2KCT-10K), look here: https://eu.mouser.com/ProductDetail/Triad-Magnetics/TY-142P?qs=Fg5d7evCuakf7g9SpG8XGQ==
If you need the likes of T1 (2KCT-10K), look here: https://eu.mouser.com/ProductDetail/Triad-Magnetics/TY-142P?qs=Fg5d7evCuakf7g9SpG8XGQ==
Probably not a whole lot different than the Triads. The Triads are a bit better than they seem at first glance - driven from lower source Z they go a hell of a lot lower than any 200 Hz. But neither the Triads or the more expensive Hammonds can tolerate any unbalanced DC in the core. Even a couple mA and they’re in saturation. Single ended operation (even on the input side) simply isn’t possible. It takes something with a bigger core or a gap as a single ended driver. Capacitively couple and they work, but you can’t just copy a classic driver stage.
I had a nice sounding Saba 6V battery powered taperecorder in my 1953 VW (6V car batteries where common back then) with about 1W or so output. The circuit resembled the one in #29.
Driver and output transformer where the same size 30mm EI-lams, the driver transformer was gapped.
It is possible i have winding details for those type of transformers, i will post them...if i can find them...but i cannot promise
Driver and output transformer where the same size 30mm EI-lams, the driver transformer was gapped.
It is possible i have winding details for those type of transformers, i will post them...if i can find them...but i cannot promise
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i made up this output stage. although it sucks and i accidentally drew an npn instead of an pnp.
Yeah, just one more CE stage, with a bootstrapped load in the collector. Direct coupled is possible if you actually have an NPN for that complementary output stage, and that if output pair is good for half an amp of peak current. No transformer at all… except the power supply.
Those devices of yours look Russian. Or from somewhere around there. The only NPNs I’ve ever had come through my hands were 2N1304’s (or was it 5’s, I had both at one time). But those are small signal devices. All the power stuff was GE, RCA, Motorola, or Japanese - and just PNP. And many of the domestic sourced ones not suitable for audio at all.
Those devices of yours look Russian. Or from somewhere around there. The only NPNs I’ve ever had come through my hands were 2N1304’s (or was it 5’s, I had both at one time). But those are small signal devices. All the power stuff was GE, RCA, Motorola, or Japanese - and just PNP. And many of the domestic sourced ones not suitable for audio at all.
The gain of the germaniums is very low and even an opamp will struggle to make much from them.
This is a 5 transistor circuit from the 70's used by Grundig and operates from a 9 volt battery. The output pair are germanium AC187/188, the rest silicon. This could drive a normal 3 way speaker with 10" bass unit to very respectable levels indeed and sound pretty amazing to me back in the day.
This is a 5 transistor circuit from the 70's used by Grundig and operates from a 9 volt battery. The output pair are germanium AC187/188, the rest silicon. This could drive a normal 3 way speaker with 10" bass unit to very respectable levels indeed and sound pretty amazing to me back in the day.