Replacing a moving coil (volt) meter with a digi display?

[Chris Wilson]

I have restored a large linear PSU and found the panel volt meter, a taut wire suspended, moving coil movement of 1mA is kaput. I doubt I will find a direct replacement, as it's late seventies, early eighties vintage. It's nice unit, very stable, nice specification, beautifully made. I would have liked to have kept it original, but given this issue my mind is turning to a digital display on a nice machined panel to go in the space the 90mm X 75mm meter occupies. I have never given such a conversion much thought. Should I be thinking of ignoring the existing wiring to the meter, which is really measuring current, and wiring a digi display direct to the output terminals of the PSU? It's 0 to 60V output (at 50 Amps, so a big beastie). I suppose a digi display would flatter the potential stability and accuracy of the thing.... Just thinking aloud here Thanks

[Rick Law]

Suggestion 1: With such a huge opening (90x75mm), may be some of those 8x8 LED matrix in 4Ledx3Led arrangement?  So 22.5mm x 25mm slot for each of those LED matrix.  The top can display current, the bottom can display voltage, and with 4 high, you can also get a DS3231 and display the date/time + temperature.

Suggestion 2: Better yet, get one of those LCD display and you can have a digital meter display as an analog meter like those dials in the airplane cockpit - and/or digital at the user's command.

[Macbeth]

You can get stacks of 2 wire or 3 wire triple digit floating point 7 segment displays in red (cheapest), green, yellow, blue for not more than a £1 each. I just bought a mix for less than beer or chippy meal money because I know I will find a use for them (and if I don't I can make a DeLorean time machine panel out of them). They have a trimmer for adjustment to a calibrated source if need be.

It's a no brainer really. Unless it's audio equipment and then you need bumping backlit analogue needles and bargraphs and stuff.

[Joule Thief]

Please read the spec sheet for any potential candidate for your supply. Some panel meters may require the addition of a small DC to DC isolated supply module for the panel meter electronics.