We're teaching a class on Napking Schematics
at the beginning of January. We won't be demonstrating Nuclear Fusion quite like that shown above, but we will be helping people learn the basics. This class is ideal for those who have an idea but are not quite
familiar enough with available 'widgets' to be able to actually build their project.
I have had the same set of calipers
for a couple years now. After awhile the screen started to blink. I couldn't be sure, but I figured this meant the battery was running low. Who reads the manual
anyway? It became obvious once the display cut out completely. Why does this always happens when you desperately need to measure something in a hurry?
Popping the small cover off showed a small coin cell battery. Foolishly, I assumed all coin cell batteries were the same 3V output. So I attached a larger CR2032 3V battery
, assuming it would simply last longer. The unit turned on but the display was completely black - all segments where on. Hmm.
Probing around google, I discovered Dave Hylands' great page on Caliper Battery Life
. It turns out these calipers are quite the battery hog. And, they use 1.5V batteries, not 3V batteries. Ooops.
I decided to create a voltage divider with a couple resistors to take the 3V of the CR2032, cut it in half, and run that 1.5V into the coil cell holder on the caliper. Digging around my tools, I came across the box of AA batteries for the Simon
boards. Of course! A fresh AA battery starts at ~1.6V, but I don't really care - anything is better than having to order a silly LR44 over the internet.
I am lucky. Hooking up the 3V CR2032 Coin cell did not ruin my digital calipers. Attaching a 1.5V AA battery with double stick tape, plus two power leads soldered directly to battery and holder inside the caliper, I have a happy, non-blinking caliper readout!