I bought these meters somewhere around 10 years ago. I don’t even remember where they’re from at this point, but I wanted to buy them because they looked cool. Do you really need any more justification than that? Not too long after that I decided it would be perfect to turn these into a clock!

I wired the meters up, printed custom faces for them and started working on prototyping the electronics. Aaaand then they sat untouched for 10 years.

That’s where I’m picking this project up from. I had to make sure the meters were still even working first. I hooked one up to a power supply set to 3.3 Vdc and the needle shot right up, way past the “maximum” level. I needed to be able to adjust the upper level to “calibrate” the meter. To do this I used potentiometers (think light dimmer) to be able to precisely set the dial at the right location. Next I connected one of the meters up to the Teensy 3.2 microcontroller I’m using. I wrote some test code in Arduino that would tell the meters what values to display in order to tell if it was all working as expected.

Once I had the test code running, I quickly realized the meter faces weren’t accurate, so I had to re make those from scratch and reinstall them. Finally I wired up the rest of the meters and wrote the clock code, based off of the previous test code I had written, integrating the RTC (real time clock) from the Teensy, that would tell the meters what time to display.

Then I hit a bit of a speedbump. I was having a problem with the RTC on the Teensy that was causing the time to not display correctly, especially when it was turned off and on again. I’m still not sure what happened but I’ll be researching solutions for the issue, and be back with those as well as building a display case for these meters when I’m back for part two of this video.

Materials:

Analog meters
Teensy 3.2
Bench Power supply: Tekpower TP3005N
Soldering Iron
Various electronic parts from DigiKey