You like the Germanium sound? This shows a 1 transistor Germanium pre amplifier & tells more (text)
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- Опубліковано 7 лис 2023
- Please read the description first for a better understanding of this video and why I made it in this way + the corrections, especially when I am talking about the Japanese code of transistors. Sorry that that was not very correct.
When you like the sound of Germanium transistors in audio amplifiers (I am not very sure about that, anyway, I have to study that sound effect much better) you can use this 1 transistor Germanium transistor pre-amplifier.
After this pre-amp, you can amplifier further with Silicon transistors or a Silicon end amplifier. Because you have, at its first stage, that Germanium amplifier.
You can use any Germanium transistor in this circuit, as long as its Hfe (current amplification factor) is between 10 (that is the lowest value, much better = 30) and (say) 70. An amplification of 10 can be too low, test that with your transistor tester.
A Hfe between 30 and 70 is better and a common value for those days, the 1960’s and the early 1970’s, for these Germanium transistors. Of course these Hfe values (30-70) are also very OK now, in 2023.
These early stage Germanium transistors can now (2023) still work properly, because the Germanium technology of those early days was studied in a very broad scale (I mean: in a scientific way). NPN transistors were, in these very early days of the transistor (1960's) less easy to make.
And/but, apart from that, all the manufacturers of Germanium transistors in those days (early 1960’s-1970’s) Philips, General Electric, Philco, and I have surely forgotten many of them in America) payed enormous attention to the quality of their transistors.
Every transistor was in those days (1960’s-early 1970’s) extensively tested, before being sold, and especially for the military and the rocket science (1960’s-1970’s) there were very strict quality rules.
By the way: these standards are a reality even now (2023): for the military certain electronic chips have to hold on to specific properties, regarding: shielding, un-sensitivity to ionization rays, mechanical stability, maximum temperature range, extremely cold and idem hot, etc.
These quality factors for electronic components (also: R, C, coils, chips, processors, etc.) are “a sea to drink”.
So in this video I am surely not going to deep dive into that. Correction (in a certain way) The Japanese codes to name their transistors was/is: "1SB" or "2SB", etc. Followed by the specific type number. That is, of course, not the JEDEC code or the pro-electron code, anyway, no problem. You have of course a transistor tester to find everything out.
The only focus in this video is this good quality PNP Germanium transistor audio amplifier.
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Germanium 1 transistor NPN transistor for an audio amp application is here
• Germanium 1 transistor...
Though that NPN-GE transistor circuit is more modern.. The idea of this video now (8 nov 2023) was to use a real old PNP Germanium transistor, out of the 1960's.
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Situation 10 November 2023. - Наука та технологія
1N = one junction = diode, 2N = 2 junctions = transistor.
OC71 wow that takes me back to my childhood !! You can scrape the paint off them and then you have a Phototransistor, this was fascinating to me back then !...cheers.
True & thanks! Some GE transistors (say e.g. the Germanium ASZ 21, GE switch transistor, only 1 example, you know that) have, by the way enormous good properties in HF and even VHF circuits. But of course such a GE transistor is very obsolete now (2023), surely not easy available now. In my YT circuits I always want to use circuits & components that can be made with "always and everywhere" (on the world/www) available (common) transistors & components, now 2020-2023. That limits surely my approaches, say for publishing circuits that are/couldbe interesting for everyone,that I cannot show on YT. Thus that is a kind of balance. And this is a serious electronics YT Channel, not a "hack" channel, getting millions of views, anyway, you will know that for sure14 nov 2023.
good videos
Thanks, good to hear that. 8 nov 2023.
Hi great informative video, I built radios etc and worked in a radio shop when I was a kid using oc71 oc44, ac126, ac127, ac128 . Af117 long time ago
The variable resistor in the emitter circuit is clever. The emmitter resitor remains the same, but the proportion of it that is decoupled by the capacitor is varied. The portion covered by the capacitor adds to the bias on the emmitter / base junction; the proportion not covered by the capacitor gives negative feedback to the signal. The amount of negative feedback will affect the distortion - more NFB = less distortion until a cutoff point is reached.
Yes, that works nice. It also has an effect on the sound, in cases of an audio pre-amps, say between 20 Hz and 20 KC. When you take 100 uF instead of 10 uF, some extra gain can be reached in the lowest audio bands, say the 30 Hertz-100 Hertz band.
A great video, thank you! I now understand more about biasing and using a potentiometer and then a fixed resistor is a very good method to adopt.
I was given a lot of old PCB boards from the 1960s and I know they have some germanium transistors, so I'll be able to experiment.
Much success & yes that bias potentiometer is the key. Say 50 % of the 1 or 2 transistor circuits published on the www don't work because of this (= made with fixed value resistors that make that the circuit does not work or does not work properly). Very sorry to say, anyway.
Especially the analog circuits, where biasing is key to get an undistorted signal out. 9 nov 2023.
@@radiofun232 Thanks for your reply, it explains a lot.
Dankuwel! Mooi om te volgen.
Graag gedaan.
for an amplifier you should also talk about phase and bandwidth. Thank you for sharing 👍
Yes, that is absolutely true. But I wanted to keep it simple, the bandwidth is (by the way) OK, because it can surely amplify between 20 Hz and 20 KC.
Very cool! I was looking for germanium transistors since guitar pedal fanatics tell me I need it for that special sound if I want to build a similar one.
Here comes the interesting part, a guy has made a circuit called "transistor piggybacking" in which you get two matched transistors and you use one of them the normal way and you add another transistor so the bases are connected together, and the second transistors emitter is connected to the original transistors emitter with a 20k potentiometer. The collector of this second transistor is unconnected. Swiping the pot makes the amplification drop and grow as you wish below the original hfe. I made a "germanium" from two cheap silicon ones. I can even add leakage if that's "wanted" haha
Very interesting! Have to see the circuit to think about a conclusion. But anyway when it works, it "works". 9 nov 2023.
I've seen similar loopbacks in oddity amplifier circuits, took me awhile to catch on why it was like that.
Great channel!
Thanks, good to hear that.
Good example pnp transistor usage. Normally we use npn transistor.
Yes, that is say the general way we use that now, 2023, but earlier, since the early1980's, that got common, when NPN Si transistors were overall used and were made very cheap, they also had better properties (lower noise, better temp. factors, much more stabile, etc, etc).
I think it's mostly guitar effects fans that like "Germanium sound", and they are referring to the sound it makes with deliberate distortion, which is apparently less harsh than in equivalent circuits with silicon transistors.
Like the original "Fuzz Face" and its clones.
Yes, the Germanium transistor/diode can be more easily "overloaded" compared to the Silicium transistor/diode. And the overload properties of a Germanium transistor/diode have different effects on the sound, or can generate a different effect, due to their low (GE) barrier voltages. By the way: a Silicon diode can also be forward biased, via a small voltage, in the range of 0-1,2 Volt, variable. That can be done with a potentiometer. Schematic of that (how that works, forward biasing, both for a Ge diode and a Si diode) is e.g. on diode detection circuits in Shortwave receivers on my YT Channel. I don't have experiences about how that (typical) distortion in case of a Silicium diode will sound, could be that it comes close to the typical Germanium transistor/diode type of distortion, though I think the Germanium distortion will be over a somewhat bigger frequency bandwidth, perhaps even into the HF band. That can be damped, of course. This must all be tested out. 9 nov 2023.
How about setting up an input and output using both channels on the oscilloscope, input on channel one and output on channel two. That way, you can monitor input distortion vs output distortion. Thanks for the video.
Thanks Barry, a very good idea. Indeed you hit the point, because the sine wave signal that I have sent in in this case of this simple 1 transistor Germanium transistor audio amp (20 Hz to 20 KC) has (of course, like "all" , say simple or hobby, thus not laboratory made) a certain distortion. The setup that you proposed will give much more information about the distortion (typicals). I have nor done that test, because I wanted to keep it "simple", but on the other hand, such a setup that you proposed can help a lot to find out what is happening in this circuit. 8 nov. 2023.
Most of the so-called "germanium sound" relates to the high input capacitance of the transistors and consequent poor high frequency response. Incidentally, the "1N", "2N" codes are US codes where the leading number originally referred to the number of junctions in the device, thus "1N4001" is a diode and "2N595" is a transistor. There were some (now obsolete) "3N" devices as well. Japanese code numbers are commonly "2SA", "2SB", "2SC" etc. The "2S" is often omitted.
Yes, however even the first Germanium transistors could reach 300 KC.
Lower forward voltage than silicon. About 0.2V compared to about 0.6V. Check out T.Henry Moray.. Germanium was one ot the components of his 'Moray Valve'.. 😊
Have got a few of them I'm gonna try it out thanks.but I have question bit of topic but I brought a airband reicever kit off Amazon how ever it works but only when I put my diy super regen airband reicever on I no it radiates is that what giving the kit enough signal to turn on thank you
I don't understand your question exactly. You have made (diy) a superreg airband receiver. And you have an airband receiver kit from Amazon. What happens exactly? Is that kit from Amazon a superheterodyne receiver?