In this instructable I am going to show you how to convert your standart multimeter's LCD into a baclkit LCD. We will use some LEDs and some clever programming to modify our stock multimeter. Thus, we will design a better product and most important we'll help ourselves do measurements in dark places!
The high-end multimeters have this function built in, unfortulantely not all of the affordable ones have it. It is handy to use the LCD backlighting sometimes, so lets just do it.
Not a problem I think - all electronic devices that have LCDs have pretty much same looking display components, if you wonder where it will work or not, just open the multimeter to see, it is straight forward.
I wanted to design the whole thing as it would be in a real off-shelf device.
After the modification there are no hanging wires and swithes, no messy batteries around.
When you press one of the standard multimeter's buttons - the yellow one in my case - and voila the LCD is lightende for 15 seconds! And what is more cool - you can program the 15 seconds delay to your preferences and change it to one minute for example!
HARD TO DO?
I'd say a bit tricky.
Step 1: Parts List & Tools
> SMD LEDs x 2 (Mine are tiny! 1.6mm (L) x 0.8mm (W) x 0.8mm (H))
> ATtiny85 microcontroller
> Soldering iron and wire
> Super glue
> Heat shrink tubes
> PC & Arduino Uno to program the microcontroler
Step 2: Open The Multimeter
Grab a screwdriver and open the multimeter. Remove the battery cover, the batteries, the back shell and then detach the PCB from the front shell. Take the LCD plastic frame out.