Volt meter for Mother X4...

[GUNHED]

Wouldn't it be nice to have a small expansion card for the CPC, which can be put into the great Mother X4 expander? Just to show you how much volts are "really" there.

My problem is that I can't find a precise volt meter. There are lots of small gadgets which show theree digits after the point (like 4,873 Volt). But the problem is that they are not even precise to 0,2 Volts.

Now my question to the hardware experts: Can we do this? Does it make sense? What else?

[Bryce]

You should be easily able to find a meter with 0.1% accuracy, the problem is, it will need to have a battery or separate power supply. Standard cheap meters usually can't measure the supply that's powering them.

Bryce.

[GUNHED]

You should be easily able to find a meter with 0.1% accuracy, the problem is, it will need to have a battery or separate power supply. Standard cheap meters usually can't measure the supply that's powering them.

Bryce.

Ah, good point. So the battery alternative may be the best choice. Because if I use an external PSU for the Volt meter... well, people may like to use the same PSU they have for CPC anyway.


How would you (as known hardware expert) do this the best way?

[Bryce]

Normally a voltage meter has to have a supply that's isolated from the source it's trying to measure. The cheapest way to do this would be to find a meter that will reliably work from a battery and will give a relatively accurate reading of the power supply in the CPC. When I get a chance, I'll see if there is any cheap ebay/chinese meter that would be suitable.

Bryce.

[GUNHED]

That would be awesome! 

[Bryce]

How about something like this, powered from a battery: https://www.ebay.de/itm/Digitales-Voltmeter-0V-100V-Einbau-Modul-0-28-LED-Display-Spannung-Anzeige-rot/184026916373

Bryce.

[pelrun]

I've currently got one of those panel meters connected to my MX4, using the same supply for measurement and power. It works well enough - I haven't bothered to calibrate it for supreme accuracy, as I just need an indication that the voltage hasn't sagged too much. I suffered all sorts of issues for years until I finally boosted the input voltage to 5.2v or so to compensate, but the dc jack from my monitor is still old and corroded and sometimes needs a wiggle to improve the connection.

[Bryce]

Some of these will work from the same supply that they are measuring, but not always, which is why I prefer to use a separate supply.

Bryce.

[GUNHED]

Thanks, that's good advice! 


Now, let use see who is willing to do such a neat thing?
Sadly I'm a bit too busy these day, but maybe we could inspire somebody to create a nice little card for the CPC / 6128plus.