build a voltmeter car

Here it is.

https://ogrforum.ogaugerr.com/t...29023675319155910ere it is.

This is the thread where the car was just being discussed. I think gunrunnerjohn had previously posted another thread about actually building the car mentioned in this thread. I looked a little yesterday and did not find it, but haven't given up looking just yet. Will post here if I find it, others pleas do the same if you find it first.

Thanks - that was driving me crazy. I will keep looking on whether we can find the build it thread mentioned. I am curious about whether it makes more sense to power with the 9v battery mentioned or whether the power supply used by Gunrunnerjohn is cheap enough. Looks like the one in the picture is a regular box car and not a hi cube.

I'm sure GRJ will make a cameo here when he sees this, but in this thread he mentions the $5 DC-DC converter module.  As mentioned earlier you need an electrically isolated power supply to use the blue AC voltmeter.  That is, you can't use the voltage you're measuring to power the meter itself.

 

https://ogrforum.ogaugerr.com/t...490#5512461172059490

 

What I'd like to see is someone install a 555 IC and a simple Voltage-to-Frequency converter circuit so you can drive a small speaker where the pitch changes with voltage.  Put it on a switch so it doesn't drive you crazy.  In any event the idea is you don't have to follow the car around the layout which can be problematic (such as in tunnels)  but rather just listen for the pitch to shift at problematic locations.  This circuit would only add a couple bucks...

The old module I used has been obsoleted, however here's a comparable model: 12V DC-DC Isolated Supply.  That's the only "tricky" part of the install.

What I'd like to see is someone install a 555 IC and a simple Voltage-to-Frequency converter circuit so you can drive a small speaker where the pitch changes with voltage.

What's stopping you Stan?