AD584 Precision Reference

I’ve been waiting for this little item for some time now… and today it turned up – a very neat Perspex box that requires micro-usb – and which gives out on demand (button press) 2,5v, 5.0v, 7.5v and 10v.

Accuracy? It is hand-written on the back. The unit outputs the following: 2.4939v, 5.00248v, 7.49906v and 10.00194v.

Or, to 3 digits accuracy, 2.494 , 5.002, 4.799, 10.001v

That’s pretty accurate I would say. So, I did what I purchased the unit for and tested my various gadgets.

Firstly the EM125 hand-held scope and meter from Banggood… 2.506 (+0.24% error), 5.007 (+0.14% error) , 7.51 (+0.13% error)  and 10.02 (+0.20% error) – I don’t think that’s bad for a cheapo hand-held scope!

Next, my trusty IO-TECH Smart-B meter… the most expensive one I have in the UK (that is about to change dramatically) – 2.48 (-0.8% error), 4.98 (-0.40% error) , 7.47 (-0.40% error), 9.97 (-0.30% error). Granted it was only £15 but that’s 4x the cheapest ones… not impressed.

Finally my Owon SDS1102 (mean voltage) 2.516 (+0.64% error), 5.079 (+1.58% error), 7,588 (+1.17% error), 10.10 (+1.00% error) – could be better – but read on..

Then I realised I had never used the self-calibration function on the SDS1102!!! I ran that and did the tests again… 2.505 (+0.20% error), 5.005 (+0.10% error) , 7.510 (+0.13% error), 10.001 (0)% error)

Not too surprising that the Owon would be the most accurate as it is the most expensive instrument. I was surprised however that the EM125 turned out to be better than my meter.

So for now, the Owon SDS1102 will be my go-to meter (not exactly pocket sized but ok on the bench) but I believe something altogether more special is on it’s way. More on that, soon.

I’ll add the BitScope later, this was not on the bench at the time.

This little test unit was cheap – and granted it is not going to find everyday use – but it certainly has put my mind at ease. The button on the front selects between the 4 voltages and long-press turns it on and off. There’s a Lithium battery inside the “case” for running without power.