Stepping down 24v to 12v for stepping actuator

[gints]

hey guys,

Im using a active low PLC with a supply of 24V, and need to run a 12VDC stepping actuator.

The board can supply 400mA, and i only need 129mA, so thats fine, but needs only 12VDC.

As I understand, the +ve supply is connected to the actuator, negative back to the output pin. Once turning "on" it pulls the output pin to 0V, hence curent flows in.

Thinking of the best way to get the 12V, do you think just a simple series resistor on the +ve supply terminal.

Drop 12V, with a draw of 128mA, so about a 100R?

Ideas?

 

[audioguru]

The 100 ohm resistor will waste 1.56W. The wasted power is more than the motor uses.

 

[gints]

so what would you reccomend? a simple regulator?

 

[Hero999]

I take it that efficiency isn't the overall goal.

I would go for something like an LM7812, just add a 100nF capacitor to the output and it'll work.

You'll also probably need a heat-sink but it doesn't need to be particularly large, a piece of aluminium plate will do.

If you want efficiency, then go for a switching regulator like the Black Regulator.
https://www.romanblack.com/smps/a03.htm

 

[Rolf]

Kiss .......

so what would you reccomend? a simple regulator?

How important is efficiency if it is not battery operated?
If the duty cycle is low a simple resistor should be sufficient. But I also think, even at 99% a switching regulator is going to be an overkill. So like in all designs you have a few choices. My philosophy is KISS (keep it simple stupid).