DIY Caliper On-Off Switch

I have this old digital caliper that is rarely used, because the battery is always empty. The issue with these calipers is that they don't have any on-off switch, so they are constantly draining the battery. Basically they only switch off the display. I don't know whether newer calipers also suffer from this problem.

It's a shame, because this is a good old caliper. Newer ones look and feel like they are made cheaper.

I've seen people on the Internet adding various kinds of switches to their calipers, even external batteries(!), but I've not seen a good solution. The issue has been finding a small enough switch that doesn't interfere with the usage of the caliper.

I was lucky with this one, because I found a switch that was a perfect fit without any modification to the caliper.

Here is my solution:

I used a small DIP switch:

DIP switch dimensions are 10 mm x 6.5 mm x 5.5 mm (length x width x height). 

On this caliper, there is a small lid on the top side above the battery compartment. Behind it is a small terminal probably meant for attaching an external cable for an output signal. This DIP switch was a perfect fit in place of the small lid. 

I filed a small notch on each side of the DIP switch with a miniature file so that the switch fit exactly in the grooves for the lid.

I made it deliberately a tight fit, so I didn't even have to add any glue to secure the switch. I had to press reasonably hard to get the switch to snap into the grooves.

I cut away the second one of the small white levers. I'm only using one part of the switch. There is no need to switch off both battery terminals.

Before snapping the DIP switch into place, I soldered two thin wires to the DIP switch (isolated with some heat shrink tubing) and placed the stripped other end of the first wire on the bottom of the battery holder so that it touched the bottom battery terminal.

On top of that, I added some kapton tape so that the battery can't touch the bottom terminal or the first wire. The second wire end is laid on top of the tape, acting as the bottom terminal for the battery. Be careful so that no wire strands touch the side terminal of the battery holder. Then the battery is put on top of the second wire and keeps it in place.

One disadvantage with the real power off switch is that now the zero position has to be set every time when the caliper is turned on.