Hi all. Newbie. First the disclaimer that apparently I don't learn like normal people do, or so the brain folk tell me - although I'm now in the twilight of what has been a swimmingly half century technical career. I learn by doing, not reading how to do - not that I find no value in the latter; but "remove bolt A" is 'what' .. real world under a bus in minus twenty with bolt A having been subjected to 15 years of road salt is 'how'. I also don't tend to 'get' what I read until I see it - or do it - in real life. That said:
So I've been playing with breadboarding low power amplifiers .. Electret mikes through 741's, simple class A common emitters with 2SC945's and 2N3904's .. today a P-P with a '945 and 2SA733.
All seem to work - and yet none do as expected. There's something I'm missing between what my scope, ears, and what the manual is telling me.
(one) test signal is also a breadboarded Wien bridge sine wave "classic" oscillator using a 741 and 7660 (for negative supply), outputting a relatively clean waveform. Asterisk .. more on that in a second.
My first experiment was to AC couple the sine wave (1.0V p-p) through a CE class A amplifier circuit with values found on the internet, and substitute the various resistor values with multi-turn pots and observe the changes in the output waveform. Agian, this is how I learn what the bits actually do. I've seen a lot of industry folk over the years who knew how to swap something out, but couldn't tell you why.
Now every text I've ever read showed the input amplitude wee, and the output an awesome order of magnitude. This has not been my breadboard experience this last week. And I have yet to find component values in any of a score of published circuits that actual;l;y do this.
Either pretty waveform transfers, OR amplitude (and even that, not much) .. but never both. I'm not certain what I'm doing wrong .. especially as everything that I've built will happily drive a 4 Ohm speaker with decent sounding audio .. but I can't seem to achieve that textbook voltage gain diagram and I don't know why.
My goal is not a guitar amp, or any one thing in particular, but to understand how to amplify an analog signal with fidelity. Sine in, sine (inverted or not) with greater amplitude out.
This should not be so difficult.
So what am I asking for? Well .. it's quite possible that you all know exactly what I'm missing and are chuckling at the moment - so that clue would help, lol. Otherwise, a known good single stage ultra clean class A common emitter amplifier schematic using discreets .. something say around 50 mV in, 3 V out that I can study and dissect.
Second, that asterisk .. My scope (set 500mV/Div) says my 1KHz sine wave is 1V p-p .. My RMS DMM set at 20VAC says it's 2. Hundred percent disagreements 'tween the two have me scratching my head.
Any help appreciated.
CD.
So I've been playing with breadboarding low power amplifiers .. Electret mikes through 741's, simple class A common emitters with 2SC945's and 2N3904's .. today a P-P with a '945 and 2SA733.
All seem to work - and yet none do as expected. There's something I'm missing between what my scope, ears, and what the manual is telling me.
(one) test signal is also a breadboarded Wien bridge sine wave "classic" oscillator using a 741 and 7660 (for negative supply), outputting a relatively clean waveform. Asterisk .. more on that in a second.
My first experiment was to AC couple the sine wave (1.0V p-p) through a CE class A amplifier circuit with values found on the internet, and substitute the various resistor values with multi-turn pots and observe the changes in the output waveform. Agian, this is how I learn what the bits actually do. I've seen a lot of industry folk over the years who knew how to swap something out, but couldn't tell you why.
Now every text I've ever read showed the input amplitude wee, and the output an awesome order of magnitude. This has not been my breadboard experience this last week. And I have yet to find component values in any of a score of published circuits that actual;l;y do this.
Either pretty waveform transfers, OR amplitude (and even that, not much) .. but never both. I'm not certain what I'm doing wrong .. especially as everything that I've built will happily drive a 4 Ohm speaker with decent sounding audio .. but I can't seem to achieve that textbook voltage gain diagram and I don't know why.
My goal is not a guitar amp, or any one thing in particular, but to understand how to amplify an analog signal with fidelity. Sine in, sine (inverted or not) with greater amplitude out.
This should not be so difficult.
So what am I asking for? Well .. it's quite possible that you all know exactly what I'm missing and are chuckling at the moment - so that clue would help, lol. Otherwise, a known good single stage ultra clean class A common emitter amplifier schematic using discreets .. something say around 50 mV in, 3 V out that I can study and dissect.
Second, that asterisk .. My scope (set 500mV/Div) says my 1KHz sine wave is 1V p-p .. My RMS DMM set at 20VAC says it's 2. Hundred percent disagreements 'tween the two have me scratching my head.
Any help appreciated.
CD.