Is this OK for a heater supply?

blacklight · 11th December 2006, 06:20 PM

Hey all. I just modeled a a heater supply for my Aikido headphone amp. It's pretty much a result of my neanderthal thinking. My mains AC doesn't swing a whole lot so I don't think a regulated supply is absolutely necessary. Anyway, would you call this idea stupid? What should I do differently?

SY · 11th December 2006, 06:34 PM

It strikes me that this is more complicated/expensive than a regulator. Additionally, you'll want to take care of common mode noise as long as you're going to all this trouble.

blacklight · 11th December 2006, 06:41 PM

Nah, I just happen to have all this stuff available from my junk box. But yes, I did think it may be smarter to just built a regulator circuit. I've never dealt with DC heaters before, so I'm a little lost here.

SY · 11th December 2006, 06:51 PM

An LM317 will work wonders.LM350 if you've got unusually high current demands.

alexmoose · 11th December 2006, 07:28 PM

what voltage are those heaters operatring at? it seems like at heater voltages, you can use FAR larger capacitances than 330uf

rdf · 11th December 2006, 08:40 PM

Aren't you dissipating >280 watts in the drop-down resistors? 2.6 amps through 41.5 ohms. Buy heatsinks.

Wavebourn · 11th December 2006, 08:56 PM

I'd use a bridge rectifier, 4,700 mkF cap, and this current limiting voltage stabilizer (12V Zener for 12.6V output, and a resistor in place of current source):

blacklight · 12th December 2006, 05:51 AM

Ah yes, seems like I didn't think ANYTHING while modeling that thing. Just forget that stupid picture. Thanks all. Back to Jones' books...

rdf · 12th December 2006, 06:53 AM

Nothing to get frustrated about, the only reason I saw it was from repetetive and explosive experience releasing the magic smoke from resistors. Now I always keep the solar calc on the bench.

Sherman · 12th December 2006, 05:58 PM

I just built a regulated DC filament supply for a hybrid amp I'm working on. Four 1N4007s,1 100uF 25V electrolytic, 1 LM317, 2 resistors (1/2W). Total cost (since I have about 10 LM317s here I got for twelve cents each) about $3.50 US. The perfboard I mounted it on is about 1/3 of the cost.

I'm thinking about making PC boards to use the LM350 per SY's suggestion for amps needing more than 1.5A of heater current. Also it would be easy to use a 12.6VAC source for both 12.6V and 6.3V heaters just by adding one more LM350 (or 317) and two more resistors.

11th December 2006, 06:34 PM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	It strikes me that this is more complicated/expensive than a regulator. Additionally, you'll want to take care of common mode noise as long as you're going to all this trouble. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

11th December 2006, 06:51 PM	#4
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	An LM317 will work wonders.LM350 if you've got unusually high current demands. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

11th December 2006, 08:56 PM	#7
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	I'd use a bridge rectifier, 4,700 mkF cap, and this current limiting voltage stabilizer (12V Zener for 12.6V output, and a resistor in place of current source): __________________ The devil is not so terrible as his mathematical model! Wavebourn: We Create Creativity!

12th December 2006, 05:58 PM	#10
Sherman diyAudio Member Join Date: Feb 2004 Location: Chicago area	I just built a regulated DC filament supply for a hybrid amp I'm working on. Four 1N4007s,1 100uF 25V electrolytic, 1 LM317, 2 resistors (1/2W). Total cost (since I have about 10 LM317s here I got for twelve cents each) about $3.50 US. The perfboard I mounted it on is about 1/3 of the cost. I'm thinking about making PC boards to use the LM350 per SY's suggestion for amps needing more than 1.5A of heater current. Also it would be easy to use a 12.6VAC source for both 12.6V and 6.3V heaters just by adding one more LM350 (or 317) and two more resistors. __________________ --Sherman

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11th December 2006, 06:41 PM	#3
blacklight diyAudio Member Join Date: Feb 2006 Location: you tell me	Nah, I just happen to have all this stuff available from my junk box. But yes, I did think it may be smarter to just built a regulator circuit. I've never dealt with DC heaters before, so I'm a little lost here.

11th December 2006, 07:28 PM	#5
alexmoose diyAudio Member Join Date: Mar 2006 Location: Michigan	what voltage are those heaters operatring at? it seems like at heater voltages, you can use FAR larger capacitances than 330uf

11th December 2006, 08:40 PM	#6
rdf diyAudio Member Join Date: Jun 2004 Location: big smoke	Aren't you dissipating >280 watts in the drop-down resistors? 2.6 amps through 41.5 ohms. Buy heatsinks.

12th December 2006, 05:51 AM	#8
blacklight diyAudio Member Join Date: Feb 2006 Location: you tell me	Ah yes, seems like I didn't think ANYTHING while modeling that thing. Just forget that stupid picture. Thanks all. Back to Jones' books...

12th December 2006, 06:53 AM	#9
rdf diyAudio Member Join Date: Jun 2004 Location: big smoke	Nothing to get frustrated about, the only reason I saw it was from repetetive and explosive experience releasing the magic smoke from resistors. Now I always keep the solar calc on the bench.

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