Digital vacuum gauge
 

I have decided to add a vacuum gauge to my dash. I think it will help me re-calibrate my manual orthopedic fuel input device. I don't have a lot of dash/gauge cluster space and I don't want to add it below my sight line. I look at my dash constantly to keep my speed in check. Unfortunately I don't have a tach, but at 30+ MPG I don't think I'm doing all that bad.

My question is......has anyone seen a digital vacuum gauge that has a display that reads like a bar graph? Something linear maybe changing from red to green or just showing more lights for more or less vacuum. I could always go with a numerical readout and just remember to keep the number as low as possible if need be. I just don't have the room for a dial style gauge.

Thanks for the help.

Check summit.com

If you can find a suitably sized 'air fuel ratio' gauge, you can hook that up via a potentiometer to your MAP / MAF sensor. Alternatively there's the ubiquitous LM317 / ten-led bar graph circuit which could be adapted for this purpose.

Yep. The circuit for the TPS LED bar graph (other thread) will also work with a 0-5V MAP sensor. The upper and lower voltage limits are different for both idle and WOT but that's it. GM sensors - at least - are not quite linear voltage vs MAP but pretty close. I intended to post to that effect in the TPS thread but wanted to try it myself first.

If you want more than 10 LEDs, the second part of the circuit, after the filtering and signal voltage divider, can be duplicated with the upper and lower limits for each LM3917 adjusted to suit the voltage ranges over which they need to be lit.