multiple regulators, 1 pot - Electronic Circuits Projects Diagrams Free

technogeek · 16th June 2007, 03:00 AM

How would you control multiple adjustable voltage regulators with one potentiometer? Can it be done?

RadioRon · 16th June 2007, 03:26 AM

Well, without giving it much thought, you could simply use a ganged multiple pot on one shaft. But that doesn't really answer the question I guess.

Leftyretro · 16th June 2007, 03:36 AM

Quote:

Originally Posted by technogeek

How would you control multiple adjustable voltage regulators with one potentiometer? Can it be done?

Certainly with enough design thought and resources it could be done. Might be brute force but your one pot could drive a DC op amp whose output could drive individual calibrated drivers that control individual regulators, it's all linear tracking DC circuits. Just matter of board space and component costs.

Many commercial DC bench power supplies have tracking plus and negative outputs using one pot when in the 'tracking' mode.

Lefty

technogeek · 16th June 2007, 04:34 AM

ooo! found this: http://www.elecdesign.com/Articles/A...4093/4093.html

I like it! I like it a lot! Parts are spendy or not available from the big 2 though.....

Roff · 16th June 2007, 02:52 PM

Quote:

Originally Posted by technogeek

How would you control multiple adjustable voltage regulators with one potentiometer? Can it be done?

What voltages do you want?

technogeek · 16th June 2007, 05:05 PM

actually I need adjustable currents, 1-5ma.

maximum 12 volts.

I'm starting to think a current mirror might be a better idea, but I need precision over a large range of operating temps and load swings.

Roff · 16th June 2007, 07:03 PM

Quote:

Originally Posted by technogeek

actually I need adjustable currents, 1-5ma.

maximum 12 volts.

I'm starting to think a current mirror might be a better idea, but I need precision over a large range of operating temps and load swings.

Well, if you want any help here, you need to define what you need.

technogeek · 16th June 2007, 07:14 PM

Okay, lets start over.

I have 6 outputs that need exactly the same current (currently using 6 regulators and 6 pots). Power supply is 12 volts. The output current will range from 1-5ma, and I need to set that output with a pot. If I change the pot setting and the output is 4.9ma, I need the rest of the outputs to be exactly 4.9ma. 5ma might be okay, but no more variance than that. It needs to be stable. I can't set it to 5ma and have it drift around to 4 or 10ma just because the components heat up to 100F or cool to 60F. Suggestions?

Leftyretro · 16th June 2007, 07:32 PM

Quote:

Originally Posted by technogeek

Okay, lets start over.

I have 6 outputs that need exactly the same current (currently using 6 regulators and 6 pots). Power supply is 12 volts. The output current will range from 1-5ma, and I need to set that output with a pot. If I change the pot setting and the output is 4.9ma, I need the rest of the outputs to be exactly 4.9ma. 5ma might be okay, but no more variance than that. It needs to be stable. I can't set it to 5ma and have it drift around to 4 or 10ma just because the components heat up to 100F or cool to 60F. Suggestions?

Two 14 pin op amps chips (8 op amps total), one pot and a bunch of resistors and a few caps for bypassing should do fine.

Lefty

ikalogic · 16th June 2007, 11:44 PM

Quote:

Originally Posted by Leftyretro

Two 14 pin op amps chips (8 op amps total), one pot and a bunch of resistors and a few caps for bypassing should do fine.

Lefty

Yes, i would recommend that idea, which is safe, very accurate, and very suitable if you don't need more than 20mA per output...

Roff · 17th June 2007, 02:32 AM

What is the maximum output voltage when the current is 5mA?

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16th June 2007, 03:00 AM	(permalink)
technogeek	multiple regulators, 1 pot How would you control multiple adjustable voltage regulators with one potentiometer? Can it be done?

16th June 2007, 03:26 AM	(permalink)
RadioRon	Well, without giving it much thought, you could simply use a ganged multiple pot on one shaft. But that doesn't really answer the question I guess. __________________ RadioRon

16th June 2007, 04:34 AM	(permalink)
technogeek	ooo! found this: http://www.elecdesign.com/Articles/A...4093/4093.html I like it! I like it a lot! Parts are spendy or not available from the big 2 though..... Last edited by technogeek; 16th June 2007 at 05:03 AM.

16th June 2007, 05:05 PM	(permalink)
technogeek	actually I need adjustable currents, 1-5ma. maximum 12 volts. I'm starting to think a current mirror might be a better idea, but I need precision over a large range of operating temps and load swings.

16th June 2007, 07:14 PM	(permalink)
technogeek	Okay, lets start over. I have 6 outputs that need exactly the same current (currently using 6 regulators and 6 pots). Power supply is 12 volts. The output current will range from 1-5ma, and I need to set that output with a pot. If I change the pot setting and the output is 4.9ma, I need the rest of the outputs to be exactly 4.9ma. 5ma might be okay, but no more variance than that. It needs to be stable. I can't set it to 5ma and have it drift around to 4 or 10ma just because the components heat up to 100F or cool to 60F. Suggestions? Last edited by technogeek; 16th June 2007 at 07:20 PM.

17th June 2007, 02:32 AM	(permalink)
Roff	What is the maximum output voltage when the current is 5mA? __________________ Ron