A Simple 10W Direct-Coupled Class-A Power Amplifier

Where we discuss new analog design ideas for Pro Audio and modern spins on vintage ones.
Prototype2
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Re: A Simple 10W Direct-Coupled Class-A Power Amplifier

Post by Prototype2 » Sat Oct 31, 2015 1:58 pm

JR. wrote:That stuff is just silly... But the audio business teaches us build it and somebody will probably buy it if it's exotic looking enough. :D

I totally agree, on both points! :) Again, I regret using the word "bling" in my initial posts - it really doesn't give you the correct impression. There's blue LED and gold-plating bling, and my kind of bling. This is my kind of bling:

Image
JR. wrote:The dedicated chip coolers are actually decent thermodynamic design, which I why I used one in my Peltier experiment.
I've always been interested in getting some peltiers to play with, but they're really just heat pumps, transferring heat from one side to another, and they usually need active cooling. I've seen people stacking them to reach crazy low temperatures (like below -20 deg C IIRC), but only with plenty of active cooling added (like water with fan cooled radiators).

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JR.
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Re: A Simple 10W Direct-Coupled Class-A Power Amplifier

Post by JR. » Sat Oct 31, 2015 3:14 pm

Prototype2 wrote:
JR. wrote:The dedicated chip coolers are actually decent thermodynamic design, which I why I used one in my Peltier experiment.
I've always been interested in getting some peltiers to play with, but they're really just heat pumps, transferring heat from one side to another, and they usually need active cooling. I've seen people stacking them to reach crazy low temperatures (like below -20 deg C IIRC), but only with plenty of active cooling added (like water with fan cooled radiators).
Yup I tried to use the Peltier effect to cool my kitchen while cooking food... great concept but (yawn) impractical.

One thing I figured out is that the Peltier effect generates and throws off heat from that process... kind of sucks when cooling stuff, but not so bad for me heating stuff up. Other problem is max temperature of Peltier is unsuitable for cooking... OK for warming and perhaps really slow cooking, but not even up to cheap crock-pot standards for heat output.

JR

PS I used a blue LED in my latest gadget. viewtopic.php?f=6&t=716&start=50#p8895 more news on that soon.
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Prototype2
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Re: A Simple 10W Direct-Coupled Class-A Power Amplifier

Post by Prototype2 » Sun Nov 01, 2015 11:42 am

Yeah, they can be used for heating stuff as well as cooling it - and you can even use them as electricity generators by heating one side (and cooling the other). Quite a versatile technology, but (as you've noticed) not all that efficient.

Your ground fault protection/detection thingy looks like a great concept! Having worked as technician on many events, including out-door festivals, I know only too well how often musicians get shocked by guitars & microphones. The most serious incident I've witnessed was the lead singer of a band falling off the stage and injuring himself after getting a shock from the microphone! In fact I think physical injuries resulting from falls after getting a shock are as common, if not more so, as death through electrocution. Having rigged lighting in a lot of nightclubs and theatres with dubious wiring while standing on tall ladders I've certainly had a few close calls, and eventually got into the habit of carrying a multimeter with me at all times...

I would definitely recommend using a red LED though, preferably blinking too - what with red LEDs being the international standard for indicating "fault", "error" or "bad", and blue the international standard for indicating "cheap", "Chinese", "junk" ;)

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Re: A Simple 10W Direct-Coupled Class-A Power Amplifier

Post by Prototype2 » Sun Nov 01, 2015 11:45 am

@mediatechnology: I just saw your post re. THAT 5263 - wouldn't this be the perfect thing to use in my case?

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Re: A Simple 10W Direct-Coupled Class-A Power Amplifier

Post by JR. » Sun Nov 01, 2015 12:11 pm

Prototype2 wrote:Yeah, they can be used for heating stuff as well as cooling it - and you can even use them as electricity generators by heating one side (and cooling the other). Quite a versatile technology, but (as you've noticed) not all that efficient.

Your ground fault protection/detection thingy looks like a great concept! Having worked as technician on many events, including out-door festivals, I know only too well how often musicians get shocked by guitars & microphones. The most serious incident I've witnessed was the lead singer of a band falling off the stage and injuring himself after getting a shock from the microphone! In fact I think physical injuries resulting from falls after getting a shock are as common, if not more so, as death through electrocution. Having rigged lighting in a lot of nightclubs and theatres with dubious wiring while standing on tall ladders I've certainly had a few close calls, and eventually got into the habit of carrying a multimeter with me at all times...

I would definitely recommend using a red LED though, preferably blinking too - what with red LEDs being the international standard for indicating "fault", "error" or "bad", and blue the international standard for indicating "cheap", "Chinese", "junk" ;)
I'll provide an update to my actual thread today to keep it together, but to answer your specific question now, I do use red to warn that ground is hot. Yellow if line and neutral are reversed, generally not dangerous, but wrong, and green for the correct wiring Line hot, with another green LED for ground present. The blue LED is just for power present, useful to know also when troubleshooting wiring.

JR viewtopic.php?f=6&t=716&start=50
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Re: A Simple 10W Direct-Coupled Class-A Power Amplifier

Post by Prototype2 » Sun Nov 01, 2015 12:50 pm

JR. wrote:I do use red to warn that ground is hot. Yellow if line and neutral are reversed, generally not dangerous, but wrong, and green for the correct wiring Line hot, with another green LED for ground present. The blue LED is just for power present, useful to know also when troubleshooting wiring.

Ah, hehe, that certainly gets an approval from the international LED signalling standards committee - though my dislike of blue LEDs is so strong that I'd opt for a white LED instead, of equal brightness to the others of course :)

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Re: A Simple 10W Direct-Coupled Class-A Power Amplifier

Post by Prototype2 » Sun Nov 01, 2015 12:53 pm

Come to think of it, won't the configuration mean that even without the blue LED there will always be two other LEDs lit? Doesn't that on its own serve as "power present" indication? "Less is more" and all that...

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Re: A Simple 10W Direct-Coupled Class-A Power Amplifier

Post by JR. » Sun Nov 01, 2015 1:13 pm

to stop feeding this veer I answered your question here viewtopic.php?f=6&t=716&p=9017#p9017

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Re: A Simple 10W Direct-Coupled Class-A Power Amplifier

Post by mediatechnology » Sat Nov 07, 2015 6:30 pm

I'm kinda lost in this thread but one thing I thought of us why not use Alps Black Beauties as the attenuator.
I have some and love them.
SSL used for the CR Monitor pot and they held up very, very well.
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