It was about time for a second digital multimeter for my toolbox and as my current one is still the one I got from my father X years ago, I decided to buy a more sophisticated one as addition.
I did not want to spend more than 100€ and my local dealer had a Uni-T UT61E1 available, so I gave it a try.
Given that I just spend 50€, the multimeter is a great deal and provides several nice features including a serial interface. What I really miss is a backlight but hey, let’s mod our multimeter…
I’m not the first one who tries to add a backlight and there are some rather cool mods including a touch sensor2 or ambient light sensor. To simplify things, my requirement was an backlight that is always on if I use the multimeter, so I just had to search for two pads that provide 9V when I switch on the multimeter.
You can find those pads just below the battery contacts, but beware that they are interchanged from the labels on the contacts. Those pads provide direct voltage from the battery, so you can either sadd some LEDs directly (with a matching resistor) or add a voltage regulator for a stable voltage.
I have a large stack of LE33 which provide 3.3V output and are really small. Inside the UT61E you will find plenty of space, so you are free to use larger regulators.
The display has two notches where you can glue either regular or SMD LEDs as you can see on the images. My blue LEDs require an additional resistor with 47Ω, so the required parts are:
- LE33 or similar regulator
- 2 LEDs
- matching resistors