[simpits-tech] Arduino PWM to Milliamp meter driver?

[Matt Bailey]

That's quite a complex circuit for such a simple task. :)

Do these gauges have only two inputs? Most of the small GA engine/fuel
indicators I've seen are D'Arsonval meters, they are designed to measure
a resistance from something like a simple analog sending unit. This
means they can be controlled directly with a variable voltage (or PWM).

I doubt you need an op-amp or transistor etc to drive the thing. Quite
the contrary, the meters I've worked with are very low-current and get
full deflection at very low voltages. Figure out how much voltage it
takes for full-scale deflection, then put a resistor in series from the
Arduino output to cut the Arduino's 5vDC down to whatever the max scale
voltage is. This way you have all of your 256 steps of resolution from
the Arduino's PWM channel.

Matt

On Sat, 17 Jan 2015 11:40:13 -0800
Ray <raysot at comcast.net> wrote:

> Got me 2 beautiful analog fuel gauges from BeechCraft. I don't know
> much about how to drive them from an Arduino though and I was hoping
> someone could point me in the right direction.
> 
> There's a few interesting circuits that I found on the Google, and
> I'm particularly interested in this one, although the input side will
> most likely nee a redesign since I'll be sending PWM from Arduino.
> 
> http://www.next.gr/rf/amplifiers/1mhz-meter-driver-amplifier-l13678.html
> 
> Does anyone have anything handy or suggestions?
> 
> Thanks in Advance, and Happy New Year!
> Ray