Been tinkering with electronics forever, and UNBELIEVABLY, I still have not grasped the basic methods around current and voltage. I know the whole water tower flow analogy, but I am still stupid.
I have a 10v valve that apparently need 23mA drive current. How do they limit the current to that valve?
The control board has a 10v, 2A supply on it that operates the valve using a pot which varies the voltage.
Can someone explain how they limit that output to (what appears to be a very low) 23mA?
It looks like they use resistors, but I can't red the values (blank SMD)
The valve will only take what it needs, not what you give it.
If it only needs 23mA, it will only take 23mA, regardless of the capacity of the power supply in amps that it is connected to.
If you connect a 10V, 100A supply to the valve and measure the current, you will see that it is only using 23mA.
Interesting. The information for the valve stated that the drive circuit must be limited to 19mA 10v preferably, and 23mA maximum. So that makes no sense then.
The datasheet is in a control panel at the office... I'll grab it tomorrow.
It definitely said supply maximums: 0-10v, 19mA (23mA max)
Perhaps it's badly worded and should have been it's consumption.
That's not right. It implies it could work on any voltage between 0 and 10V.
I think that is a specification for a control signal and not the supply voltage and the current specification is the maximum it would draw.
So to control the valve you need a signal that goes from 0 to 10V and the signal source should be capable of providing a maximum of 23mA