trimmer pot voltage regulator

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keithg
 
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trimmer pot voltage regulator

Post by keithg »

I am an artist making a series of http://ifugaopaperblog.tumblr.com/ made of Fisher Price toys. These include a board with sound, LEDs, and motors. I want to use four or five with each mask from a single 12v battery and one speaker. I have made the 386 amplifier but have failed to make a successful power source after hours and hours of experimenting and searching web resources. The 7812 regulator is fine but the toy circuit/amp circuit are not. I am trying to power the 386 amplifier circuit and the toy from two of the trimmers http://i189.photobucket.com/albums/z215 ... rimmer.jpg. When using the batteries native to the toy the circuit runs as expected directly to the amplifier circuit. Any advise would be appreciated.

[Edit - mod - fixed links]

keithg
 
Posts: 82
Joined: Thu Oct 30, 2008 8:30 pm

Re: trimmer pot voltage regulator

Post by keithg »

Here is a not so professional drawing of what I am trying to describe.

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adafruit_support_bill
 
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Re: trimmer pot voltage regulator

Post by adafruit_support_bill »

You are trying to use the 100K trimmers to regulate to 3v for the toy and 8v for the amp? The output of a simple voltage divider will change when you load it. You will have better results using a true voltage regulator.

There are other regulators in the 780x family, including a 7808 and a 7803. Although using a linear regulator to get from 12v to 3v is rather inefficient and the regulator will get pretty hot. Another option would be to use switching regulators such as the ones from here: http://www.dimensionengineering.com/

keithg
 
Posts: 82
Joined: Thu Oct 30, 2008 8:30 pm

Re: trimmer pot voltage regulator

Post by keithg »

Yes, you are correct; when loaded, the trim pots are unpredictable. I assumed a 12v battery pack would be necessary to power 5 of these toys with their LEDs, sound recordings, and a few small motors. Not all would be active at the same time. If heat is a problem, possibly 8v would suffice. Does the regulator you mention have multi line out? Would http://www.analog.com/en/power-manageme ... t.htmlthis be a cheaper alternative? Thanks for the advise.

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adafruit_support_bill
 
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Re: trimmer pot voltage regulator

Post by adafruit_support_bill »

Not sure which LM386 amplifier circuit you are using, but most will operate anywhere in the 4-12v range. If you can get acceptable output volume with a supply in the 6v range, it will put less stress on your 780x linear regulators.

Switching regulators are much more efficient and will run cooler with higher input voltages. But still, there is no reason to have a primary supply higher than what the amplifier needs.

Do you have some idea of how much current the toy circuits need? This module will supply up to 3A at 3v & can probably drive a bunch of them wired in parallel.

The Analog Devices device in your link will only work with up to a 5.5v supply.

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