LM386 but on AC?

tubbytwo · 23rd November 2004, 10:58 PM

Is there such a thing as an amp similar to the LM386 but made to operate on AC? I'm looking for such an animal to be powered by about 6 to 13VAC. DC is almost out of the question because of AC hum. I don't want to use a diode and cap to supply DC if I don't have to. . Just thought I'd ask.

paulb · 24th November 2004, 01:43 AM

Quote:

Originally posted by tubbytwo
DC is almost out of the question because of AC hum.

I don't understand what you're saying here.

Quote:

I don't want to use a diode and cap to supply DC if I don't have to. . Just thought I'd ask.

One diode and one cap is a problem?

Anyway, the answer is no, you need to convert the AC supply to DC before you can amplify a signal with it.

tubbytwo · 24th November 2004, 04:42 AM

Sorry for the confusion. My original question was, is there a small chip amp SIMILAR to an LM386 that operates on AC. In my mind they have everything else so I thought there might be one with it's own built in DC "power supply" that would run on AC. "One diode and one cap is a problem" ...no, but it needs either to be isolated from the underside of this transmitter or encased in a metal can. It picks up hum. I've tried it. This is a one tube transmitter and I wanted to hide it. I guess I could put the whole thing in an IF can on top to keep with the antique theme.

kilowattski · 24th November 2004, 06:21 AM

No such animal. I don't think there ever will be either.

macboy · 25th November 2004, 03:01 PM

The only things that can run from AC are resistive heat makers (like heaters and filament lights and stoves), some kinds of motors, and flourescent and neon type lights. Every single other thing that you plug into an AC line has a built-in power supply to convert AC to DC. You'll need to do the same.

If you are picking up a lot of hum, use a bigger filter cap. Try using a regulator. You said you have 13 VAC, so after rectification that is about 18 VDC, which is far too high for the LM386 anyway. The regulator will significantly reduce the AC ripple on the power supply for the LM386.

demogorgon · 27th November 2004, 07:38 PM

and if even not regulation will do the tric, then batteries will.

think you'l have a hard time finding AC in those.

regards
marius

EWorkshop1708 · 29th November 2004, 01:38 AM

You can't run an amplifier directly on AC. If you did, it wouldn't work, and you would get hum in the speaker, and most likely fry the amp.

Just use a small diode bridge rectifier and a filter cap when you make your amp, so you can power your amp with AC because it gets converted to DC.

[/thread]

23rd November 2004, 10:58 PM	#1
tubbytwo diyAudio Member Join Date: Nov 2004 Location: Burbank CA	LM386 but on AC? Is there such a thing as an amp similar to the LM386 but made to operate on AC? I'm looking for such an animal to be powered by about 6 to 13VAC. DC is almost out of the question because of AC hum. I don't want to use a diode and cap to supply DC if I don't have to. . Just thought I'd ask. __________________ -Mike

24th November 2004, 04:42 AM	#3
tubbytwo diyAudio Member Join Date: Nov 2004 Location: Burbank CA	Sorry for the confusion. My original question was, is there a small chip amp SIMILAR to an LM386 that operates on AC. In my mind they have everything else so I thought there might be one with it's own built in DC "power supply" that would run on AC. "One diode and one cap is a problem" ...no, but it needs either to be isolated from the underside of this transmitter or encased in a metal can. It picks up hum. I've tried it. This is a one tube transmitter and I wanted to hide it. I guess I could put the whole thing in an IF can on top to keep with the antique theme. __________________ -Mike

24th November 2004, 06:21 AM	#4
kilowattski diyAudio Member Join Date: Aug 2003 Location: Long Island, New York	No such animal. I don't think there ever will be either. __________________ ----------------------------------------------- It's Alive, It's Alive! Kilowattski

27th November 2004, 07:38 PM	#6
demogorgon diyAudio Member Join Date: Jul 2004 Location: Behind you.	and if even not regulation will do the tric, then batteries will. think you'l have a hard time finding AC in those. regards marius __________________ A furore normannorum libera nos domine. "...democracy is, properly speaking, necessarily a despotism, because it establishes an executive power in which "all" decide for or even against one who does not agree; that is, "all", who are not quite all, decide, and this is a contradiction of the general will with itself and with freedom." -Immanuel Kant

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25th November 2004, 03:01 PM	#5
macboy diyAudio Member Join Date: Oct 2003 Location: Ottawa, Canada	The only things that can run from AC are resistive heat makers (like heaters and filament lights and stoves), some kinds of motors, and flourescent and neon type lights. Every single other thing that you plug into an AC line has a built-in power supply to convert AC to DC. You'll need to do the same. If you are picking up a lot of hum, use a bigger filter cap. Try using a regulator. You said you have 13 VAC, so after rectification that is about 18 VDC, which is far too high for the LM386 anyway. The regulator will significantly reduce the AC ripple on the power supply for the LM386.

29th November 2004, 01:38 AM	#7
EWorkshop1708 diyAudio Member Join Date: Nov 2004 Location: Florida	You can't run an amplifier directly on AC. If you did, it wouldn't work, and you would get hum in the speaker, and most likely fry the amp. Just use a small diode bridge rectifier and a filter cap when you make your amp, so you can power your amp with AC because it gets converted to DC. [/thread]

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