Basic troubleshooting - Multimeter Comparison

I'm sometimes asked the question "How much should I spend on a multimeter?". Of course the question isn't quite as simple as that, because if you want a good brand like a Fluke, the cheapest I found on Amazon was £80, and if it's something you use infrequently, then that price is really rather a lot to pay.

At the other end of the scale, the cheapest general purpose multimeter I could find on Amazon was £4 plus £1 delivery. That's just £5 for a multimeter, but that's OK right, because I can afford that, and it's just a multimeter right?

Well, not so much. I ran some tests here with a bench power supply to guarantee a stable voltage and put the £5 multimeter (Don't ask me why I own one!!) up against my own £29.99 multimeter to see how it fared.

I would say the £29.99 was bought for £12.99 when I managed to hit a deal on Amazon, purely by accident, and the same meter can still be found for less than £29.99, and is robust, autoranging and has a lot of features including mains power detection, which I've found very useful when fitting lights in my new house!

Here we are at 5V:

And at 9V:

And finally at 12V:

I chose these voltages simply because they are common ones I use for retro machines.

So what is the takeaway here? Well, as you can see, in the case of the cheap meter, it read universally low, and this could lead you to believe your PSU is not putting out the correct voltage.

If you were then to adjust it up, you may find yourself in the position, like here, of adjusting up to 5V and the actual output really being 5.16v. Now that will likely be ok, but what if it was reading even lower to begin with, say reading 5v as 4.5v?

You adjust it up to 5v, and now you're actually at 5.5v. Now the ICs may be fine with that, but long term it may be a problem, especially if the voltage happens to drift up for any reason.

The advice here really is, don't buy a cheap multimeter, it may cost you a lot more in the long run.

If you can afford that Fluke, then why not, but my advice would be to look for something is somewhere in the middle, say around the £30-£40 range, and if you can, see if you can find a deal and get some money off.

£5 may seem like a great deal, trust me, it's not.