Need Help!- reduce voltage...

[Coogrrr]

I have the Xylotex 4axis controller and it wants from 12 to the recommended 24 volts DC.

I have a controller power supply but it puts out 35vdc. That is the top and not so recommeded power amount that the Xylotex should ever have.

My question is this. What piece do I put on the 35vdc output of the PS to make it 24vdc into the Xylotex controller? do I place a resistor inline if so what size is recommended? do I put a resistor across the + to the - instead and if so again what size?

I am able to solder and build by plan circuitry but my electronics theory is way short... Can one of you whizzes at this give me a hand?

TIA!!!

Coog

[Ajax-oz]

Coogrrr,
You may already have the answer to your question and his is not needed but I will give you my answer.

first part of your question

To drop a voltage you put a resistor in series. To determine the resistor value you use OHM's law

Resistance (R) = voltage (V) / current (I)

Second part of the question

But in your situation you have a problem.

If you put a resistor in series with the motor controller as the current draw increases due to driving the motors the voltage across the resistor will Increase V=IR

in turn decreasing the voltage across the motor controller. that will mean the motor needs more current to drive, drawing more current decreasing the voltage again, and so on, and so on.

So my recommendation is to either modify the power supply to output 12 -24 volts (not using a resistor in series)

or get another power supply.

Hope this helps.

AJ

[Coogrrr]

The information given is invaluable and I have it in my notes now. I am taking your advice and getting another Power Supply as I dont want to mess up the one I have it is a nice unit. I wont do the series resistor but still good to know!

Coog

Originally Posted by Ajax-oz Coogrrr, You may already have the answer to your question and his is not needed but I will give you my answer. first part of your question To drop a voltage you put a resistor in series. To determine the resistor value you use OHM's law Resistance (R) = voltage (V) / current (I) Second part of the question But in your situation you have a problem. If you put a resistor in series with the motor controller as the current draw increases due to driving the motors the voltage across the resistor will Increase V=IR in turn decreasing the voltage across the motor controller. that will mean the motor needs more current to drive, drawing more current decreasing the voltage again, and so on, and so on. So my recommendation is to either modify the power supply to output 12 -24 volts (not using a resistor in series) or get another power supply. Hope this helps. AJ

[Odin M Yggdrasi]

If you can find one, a 7824 Voltage Regulator IC in a standard usage should also be able to provide what you need, plus the regulation of it would likely improve machine reliability if your filter capacitors were good.

[Al_The_Man]

If this is a linear non-regulated supply you could look at the possibility of removing some secondary winding turns.
A typical turn count would be 3 turns/volt.
And it is about the most efficient method.
Al.