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Adjustable 5 volt DC pot

winr

winr

Diamond Member
Hi.

I have a rotary switch that has a 5 volt DC in.

As it turns from one side to the other it has .5 volt DC to 4.0 volts DC out.

I need to lower the .5 out with something adjustable like a rheostat or pot.

Thanks.

🙂
 
It is a rotery switch with click stops?

What exactly are you trying to do? Does the 0-.5 v need to be just one value (ie 0.25 instead of 0.5)) or more than one value?
 
It is a tiny load.

My mistake, it is like a light dimmer switch, it turns about 1/2 turn lock to lock.

In other words it has a stop in each direction that keeps it from rotating all the way around.

It starts out around .5 volts DC from one stop.
As it it rotates the voltage gradually increases to around 4 volts DC until it hits the other stop.

What I wish to do is have the .5 volts start out around .4 volts and still increase in voltage as the switch turns.

As an example, it would start out at .4 V and end up at 3.9 V instead of .5 V and 4.0 V.

I hope this is clearer.

Would a resistor do this?

Regards.

Richard.

🙂
 
A light dimmer? Either a small globe or an LED I'm guessing...

Depending how you set it up, you could have it go 0.4V - 3.9V or 0.4V - 4.0V. A resistor can do this, although you will need to find what current is flowing before you can calculate which resistor to use.

RoD
 
Is the current pot controlling a variable voltage regulator or is it attached directly to a load? Most variable voltage regulators have a minimum and a maximum. Perhaps that is what the stop on the pot is for - to prevent exceeding some designed maximum. You would have to find out the specs of the variable regulator to find out what size pot you would need to change the output range. And even then, .5V might be the design minimum. In that case, a resistor on the output of the regulator could still shift the range that would appear on the load. We just need more info.

.bh.
 
Your explanation of what you are trying to do is inadequate to provide a correct answer. I can't post a complete education in basic electricity in one post, but you need to know the range of current required to get the brightness range you want.

For a very low power lamp, a variable resistor might work. If it requires much power, at all, you could end up with a flaming resistor under some conditions.

With the proper information, the answer is simple. You can PM me for a little help, or you may get some help from another member or a local friend.

IF YOU DON'T KNOW WHAT YOU'RE DOING, DON'T DO IT.
 
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