Hi all, got a potentially easy question (I hope!). I am using Arduinos on my homebuilt flight simulator....currently I'm using one to read a rotary switch on a weather radar, another to read the frequency setting and drive a light on a real transponder (a common aircraft radio). I also am driving a real flap indicator gauge, a vertical speed indicator (easy servo instrument), and a temperature gauge....I gotta say I am loving these boards, any of the "off the shelf" flight simulation solutions couldn't do nearly as much and would cost 10x the price!!!!
Anyways, I have a slightly new challenge. I have a fuel quantity indicator that, despite 12+ pins in the back, appears to be a simple D'Arsonval meter. Varying the voltage on one of the pins moves the needle. Trouble is, it takes about 28v for maximum deflection.
I've been using the Arduino's PWM for running similar analog instruments. So, what I need is a simple circuit to step the Arduino's 5v PWM output to 28v. I did some reading about FETs and other things that seemed to be geared to heavy loads, but I'm thinking that's all overkill since the load from this meter will be almost nothing. I just need to step up the Arduino's output. Is there a simple and safe way to do this without a complex circuit?
One thought I had was using transistors to switch the meter to a 28v source, I just don't know if a transistor would switch fast enough to keep up with the Arduino's PWM. Bad idea?