# A quick question about a rheostat



## Steff345 (Sep 14, 2007)

hi

i have a 10K volume control (rheostat) with me and I am thinking of using it as a dimmer on an array of LEDs mounted inside my case (runs on 5v off an AC/DC adapter)

when I connect the rheostat to the circuit, the lights are very sensitive - what i mean is that even a small turn of the knob will result in the light getting very dim..

this is to be expected since i assume that 10K is far too much max resistance for such a purpose, and the sensitivity issue is no big deal for me...

my concern is this - will there be any issues (concerning the circuit and its power supply) in using the 10K rheostat in this array?


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## jquisgard (Jun 12, 2010)

The problem isn't necessarily the impedance of the volume control, Its the way a volume control works. They increase and decrease the voltage exponentially not gradually. As far as causing problems for the power supply or circuit there could potentially be problems depending on the type of power supply and Volume control, These typically have internal electronics and they do catch fire even with low current. (I've had to go and replace plenty of them).


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## Steff345 (Sep 14, 2007)

jquisgard said:


> The problem isn't necessarily the impedance of the volume control, Its the way a volume control works. They increase and decrease the voltage exponentially not gradually. As far as causing problems for the power supply or circuit there could potentially be problems depending on the type of power supply and Volume control, These typically have internal electronics and they do catch fire even with low current. (I've had to go and replace plenty of them).


hi - thanks for your reply..

i must admit im just a beginner when it comes to electronics - so if it is potentially dangerous to use the rheostat (volume control) in my case as a dimmer for the array of the LEDs - what should I use for this purpose?


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## jquisgard (Jun 12, 2010)

I was thinking about this and I wonder if I misunderstood what you meant by "volume control". Is it a volume control that came out of a wall in a house or a stereo, or is it just a simply just a naked rheostat with a post and two or three tabs to solder the connections to. I'm starting to think it's the latter. As for dimming the led, I don't think led's like being dimmed by nature because of the way diodes work, You may need a way to cycle them on and off really quick. I'm going to check it out.


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## Steff345 (Sep 14, 2007)

jquisgard said:


> I was thinking about this and I wonder if I misunderstood what you meant by "volume control". Is it a volume control that came out of a wall in a house or a stereo, or is it just a simply just a naked rheostat with a post and two or three tabs to solder the connections to. I'm starting to think it's the latter. As for dimming the led, I don't think led's like being dimmed by nature because of the way diodes work, You may need a way to cycle them on and off really quick. I'm going to check it out.


yup.. i meant the latter.. Just to be more precise, here's a pic of it except in the pic its a 470K whereas my one is a 10K..


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