Tag Archives: Multimeter

Best beginner’s auto-ranging Digital Multimeters (DMMs) compared and reviewed

With the current DIY/Maker movement in full swing, one thing that almost all of us need is a good Multi-meter. When shopping for one, it was decided right away that a good entry-level multimeter for beginners had to be:

  • Digital
  • Auto-ranging
  • under $50

Why these 3 criteria?

Digital for high precision, Auto-ranging to eliminate the need to switch the dial every time something changed, and $50 maximum to keep this within the budget of most DIY’ers/Makers like you and me. (As an aside, the requirement for an Auto-ranging feature also makes the minimum around $20.)


After perusing Amazon, it was discovered that 8 models fit this criteria. The biggest problem was that all 8 of them reviewed really well typically averaging between 4.4 and 4.7 stars.

The customer reviews were okay for getting a feel of each model, but they were so inconsistent that there was no way to compare and contrast one model with the next. So one of each was purchased and immediately we began the going over of the models while poking and prodding each one.

Continue reading Best beginner’s auto-ranging Digital Multimeters (DMMs) compared and reviewed

Bathroom Laser Light project — the analog version

A few weeks back, Redditor /u/doakey posted an insanely cool idea to /r/arduino of lighting up his toilet bowl with a red laser so that when he got up in the middle of the night to pee, he could see where he was “shooting”, so to speak. And it was a grand success!

Walk into the bathroom. Laser shoots into the bowl. *pew, pew, pew* Lights up the target like a spotter for some stealth aircraft to hit with a smart bomb. Night vision preserved. Mission accomplished. Laser turns off. Then you go back to bed.


Yet, he noted that the 9v battery only lasted a few days. Naturally, a few of us pointed out that an Arduino is overkill and that he could have done this using analog electronics.

And I get it. Analog is pretty hard. Arduino is relatively easy. There are plenty of resources out there on how to program Arduinos, but analog… well, it is kind of on its way to becoming a “lost art”.

A few people in /r/arduino asked me to write-up my proposed analog verson. After a few weeks of fiddling, here’s the analog circuit (and explanation) I came up with to reproduce the same effects…

Continue reading Bathroom Laser Light project — the analog version

The portable LED USB multimeter (that you didn’t know you needed)

Update 08/01/2016: If you’re looking for full-size multimeters with USB support. There’s a new article on budget DMMs. Of which 2 DMMs have USB data connection support.

The USB port is one of those things in the 21st century that provides the necessary “lifeblood” (electricity) to charge and re-charge all of our fancy cellphones and gadgets. Yet rarely in this process is there a good way to know that things are going well in the power transfer process. Maybe you’ve experienced plugging in your phone to charge and yet for some reason it doesn’t appear to take a charge or perhaps it’s just charging too slowly. And how does one figure out what to do about this? Surely, there is a little gizmo that can help us out here!


And sure enough, there is. In fact, there’s more than just one. There’s a whole bunch of them. They go by the names “charger doctor”, “USB detector”, “USB meter”, and even “USB power monitor”. At the end of the day, they’re mostly just digital multimeters designed for the USB port, but what they do is insightful!

And the best part is that they sell for under $15.

Continue reading The portable LED USB multimeter (that you didn’t know you needed)