Day 38, Multiple multimeters
First of all, let it be said that I'm mostly a software guy. To the extent that I build things (radios, electronics, or woodworking) I'm mostly self-taught and therefore only been trained by someone as ignorant of things as I am. But a lot of the garage gems that I've been posting are tools that I use in pursuit of these more physical endeavors. At various times I've dabbled in electronics, and when you do that, you probably are going to want to have a multimeter. In fact, you may wish to have more than one multimeter.
For those who know only a bit less than me, you might not know what a multimeter is. Well, it is a gadget that measures electrical quantities, most commonly voltage and current. One thing I've done with this collection is understand the voltage and current coming from a surplus solar panel that I bought for tinkering with. To measure the output power of a panel, you need to know both the voltage and the current produced by the panel, and you multiply them together (power is the product of voltage and current). While there are purpose built monitors that can tell you that (or any of number of DIY projects you could construct to do so) for just tinkering, you can measure the two separately using two different multimeters.
But this is a gem series, meant to highlight the physical artifacts, not explain them.
I have three multimeters that I use for most of my tasks, which usually means I can find one when I need it.
The first is a Radio Shack Model 22-805 multimeter. A few things suggest that it's fairly old:
- First, it's a Radio Shack Multimeter, and radio shack went out of business in 2015.
- Radio Shack actually made a different model, the 22-812 which was a later model that replaced this one.
- It has a computer interface (snazzy), which is not USB, but rather a conventional (for the time) RS232 port.
I think I bought this about thirty years ago, but it might have only been twenty five years or so. But it's
still in great condition, and while it has pretty much just the basic functionality that you would expect from
a multimeter, it works well, and I have (once or twice) used the RS232 port to log data to my main computer.
A quick survey for this model on Ebay suggests that they still can draw a fairly good price, which makes me
believe that others think these are pretty good too.
It has good battery life, and (importantly) will auto power off when not in use to preserve battery life.
Which brings me to this multimeter, the PROTEK D903.
I frankly don't remember how or when I got this thing. My brain tells me that it's the cheapest possible multimeter, but it's not really true. I've got no real gripe with it except one thing, and it's pretty much a deal breaker: it doesn't auto turn off to preserve battery life. You can see from the photo that I added a reminder to turn it off with my label maker because on multiple occasions, I've gone to use it and had the battery be dead because I failed to turn it off. That's too annoying for words. For all I know it's not bad, but basically I think of this one as similar to the $7 models that you can buy for Harbor Freight any day of the week.
The last is my daily driver, the ANENG AN8008:
You can still buy this multimeter from amazon for about $25-$30 (maybe soon to rise from tariffs) but in the past people have managed to get these for less directly from China. In addition to the usual functions, this one also includes the ability to measure capacitors, as well as frequency.
And most importantly, it auto powers off.
A potentially useful thread about this particular model is on the eevblog website, although I've done none of the associated hacks or changes, or even calibrated it.
If you have more specialized requirements (such as working on lots of higher voltage AC, or need higher precision) you probably would scoff at any of these, but for the kind of DIY/hobby stuff I do, these things are quite useful and won't break the bank.
Hope Monday finds you all well.