Some days ago I've bought 5x 10 of
these LED DC voltmeters which can measure from 0V to 100V.
As promised yesterday on discord I played around a little bit with them.
Here are some pictures of them. I tried to compare the brightness and colours of the displays but I think I need a better camera than the one in my Sony Xperia Z3.
I have powered the displays with 5V but they can do the range from 4V up to 40V.
The displays are coming with three wires, yellow, red and black.
black: GND
red: 4 ... 40V
yellow: input, 0 ... 100V DC against GND
Ok, let's start with the pictures.
Front and back of the disply. I think the trimpot is for adjusting the meter but I haven't tested this yet.
The holes are good for M2 screws.
Comparison of the displays. The green one is the brightest, followed by the blue one and then white, red, yellow.
The order of the colours is from left to right: white, blue, green, yellow, red
White is looking much nicer with the naked eye than on the pictures.
I tried different settings with the camera and these are the best results I got.
The colours in detail
Here are now the measurements. I started at 0V and went on with these points: 1V, 5V, 10V, 25V, 50V, 75V, 98.71V, 100V.
At 98.71V the first display (green) reached the 99.9V
The BM235 on the left is showing the supply voltage of 5V and the 121GW is showing the input voltage.
All displays are connected in parallel.
As you can see, they need a bit of tweaking which I hope can be done with the trimpot on the backside.
Besides that, they are nice little displays and they are having a resolution on 10mV in the range of 0 to 10V and then they are switching automatically to the 100mV resolution in the 10 to 100V range. No leading zeros.
All in all not that bad for 1 EUR per piece.
Which brings me to my last point:
If somebody of you is interested in playing around with these little buggers, send me a PM.
I'll give away 3 batches with five different colours. Price per batch 5 EUR plus shipping (EU + UK).
First come, first serve.
Thank you for watching.