Quote from: MarkT on Jul 28, 2012, 03:21 amWhat is the load?I need to send a signal of between 0 and 12 Volt to an electric-over-hydraulic trailer brake.
What is the load?
You seem to be making hard work out of this project.
You can drive an open collector transistor or FET from the arduino. Your 50ohms load is connected between your 12 volt supply rail and the collector of the transistor.
If there's a datasheet for the device it would be really re-assuring to see it - I don't know how such a thing works and what sort of frequencies of PWM are suitable.
Also automotive devices often are permanently connected to the chassis/ground and can only be switched on the high-side - if this is so you'll need a PNP or p-channel device to switch and some kind of level-shifting circuit to control this from the Arduino.
I can't do that because I only have one wire that goes to my "load." Not two.
QuoteI can't do that because I only have one wire that goes to my "load." Not two. No you always have two wires to connect to the load otherwise you can't get any current to flow.Your other "hidden" wire is either the ground or the +ve power supply.What do you need to do wit this wire to turn it on. If it is supply +ve then the ground is your other control wire.