shimniok
Member
I've been playing around with the Heathkit IG-4505 oscilloscope calibrator circuit diagrams as I am trying to build my own for fun.
Turns out it amplifies a logic level square wave (up to 1MHz) to as much as 100V peak. It does this with a simple transistor amplifier. Which is actually pretty easy, really, since it is simply a case of turning the transistor on and off. Reproduced for educational purposes:
**broken link removed**
Caveat -- I haven't really gotten around to playing with this "in real life"
And I seriously doubt it can support 250W output!!
As for AC amplification, starting with millivolts and ending up with 50V ... well, turntable cartridges output alternating signals around 2mV and amplify this to a signal that swings 50-100V or so. So, audio amplifier as stated above isn't a bad model I suppose? Although they use AC supply with + and - rails. And a sh~71oad of transistors. And it's not simple.
For sake of reference, my vintage HK680i receiver uses ±43.5V rails, outputs 70wpc into 8Ω ... uses two giant Toshiba power transistors as well as probably a dozen transistors just on a single channel driver board. To say nothing of the phono preamp which I haven't even glanced at yet. A 250W amp would be more involved, I imagine, but certainly those exist too.
Maybe add a DC component to the AC so at least you're dealing with a single +DC power supply?
Michael
Turns out it amplifies a logic level square wave (up to 1MHz) to as much as 100V peak. It does this with a simple transistor amplifier. Which is actually pretty easy, really, since it is simply a case of turning the transistor on and off. Reproduced for educational purposes:
**broken link removed**
Caveat -- I haven't really gotten around to playing with this "in real life"
And I seriously doubt it can support 250W output!! As for AC amplification, starting with millivolts and ending up with 50V ... well, turntable cartridges output alternating signals around 2mV and amplify this to a signal that swings 50-100V or so. So, audio amplifier as stated above isn't a bad model I suppose? Although they use AC supply with + and - rails. And a sh~71oad of transistors.
And it's not simple. For sake of reference, my vintage HK680i receiver uses ±43.5V rails, outputs 70wpc into 8Ω ... uses two giant Toshiba power transistors as well as probably a dozen transistors just on a single channel driver board. To say nothing of the phono preamp which I haven't even glanced at yet. A 250W amp would be more involved, I imagine, but certainly those exist too.
Maybe add a DC component to the AC so at least you're dealing with a single +DC power supply?
Michael
