Simple HT supply build

[Mike Watterson]

The mini 3 digit voltmeters: 12 off for £8.77 on Amazon.

AZDelivery Module Mini Digital Voltmeter Panel 2,5V-30V DC 0.28 Inch with 7 Segment Display Voltmeter 2,5V-30V DC

The Mini Voltmeter allows the reading of the voltages in a simple and fast way.
Due to its characteristics, the Module is perfect to be installed in a house or another structure for a long time.

Since it has Welded Cables the quick test of batteries or accumulators can be developed.
In addition to its versatility, it has an easy connection.
Just connect the black cable to the negative pole of the battery and the red cable to the positive pole of the battery.

The reverse polarity protection makes it safer to use, especially for temporary installations.
In case the reading is very accurate, the voltmeter can be calibrated, through the potentiometer on the back.

The different colours displayed on the screen have different minimum voltages.
This is because different coloured LEDs require different amounts of voltage to illuminate.
So, each colour reflects a different range, the voltmeter with the red screen can measure from 2.5 to 30 V.
The modules with the green screen and the yellow screen work from 2.6-30V and the blue screen from 3-30V.

✔️ Measuring range: 2.5V/2.6V/3.0-30V.
✔️ Operating voltage: Minimum 3V.
✔️ Screen: 0.28" LED.
✔️ Screen colours: Red, Green, Yellow, Blue.
✔️ Measurement accuracy: +- 5%.
✔️ Cable length: approx. 20 cm.
✔️ Dimensions: 31x14x10mm.
✔️ Weight: 4g.

I recommend opening the solder link and a 5V PSU. Spare pad is the voltage measure. I'll check what series resistor they need for x10 = 300V. I'll power one with a floating/isolated 5V supply and connect the 0V connection to -HT via a scale resistor and V sense in to HT supply 0V.