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John, Engineer and electronic enthusiast for more than 12 years.
Category: Consumer Electronics
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I have a product that was designed and made in China. It has

Customer Question

I have a product that was designed and made in China. It has a dial that turns a potentiometer to utilize 15v dc to power a rotary small massager motor.
Problem: the China engineer says that he had to absorb 6v into an aluminum strip in order to utilize a single turn to power the motor from 300 rpm to 800 rpm. The massager handle gets very hot.
There is a on/off timer chip that I believe is controlled by the potentiometer, and lays on the aluminum strip which I believe acts as a heat sink,but I can't tell how the engineer "shunted" the first 6v "into" the aluminum strip.
I need help to analyze the circuit board and tell me how to do this without creating the heat. My original suggestion was to use a double turn potentiometer and set it up in such a way that only the last turn is available to the user, and conceivably from 7.5v to 15v to power it from slow to high speed and not generate high heat...or tell me that the way China did it is the best I can expect.
Submitted: 1 year ago.
Category: Consumer Electronics
Expert:  Russell H. replied 1 year ago.

Hi, thank you for contacting My name is Russell. I will do my best to provide the right answer to your question.

That is a problem of the power circuitry arrangement, mostly.

Can you post a photo of the circuitry in the product in question?

The power excess may have been 'shunted' through the aluminum strip by passing part of the power path through it, possibly. But I cannot tell without either schematics or a good photo.

Use the Reply To Expert function to let me know - and also, use the paperclip icon to add a photo file to your Reply.