My wife recently started her own business of making personalized products and decorations and for her manufacturing she needed digital calipers to properly measure things.

We got two different ones made by Parkside and both of them work great with one caveat. In storage, they will occasionally turn on by themselves and if they stay unnoticed, the battery will be drained when we would need them the next time.

To mitigate this, I decided to modify both calipers and to add a switch in between the battery and the circuit so that there is no chance of them turning on by accident or on their own.

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Opening the calipers

To open the calipers, there are a number of screws from the back under the sticker with the manufacturer details. Once these are removed, the plastic housing can be separated and the PCB is then exposed.

To remove the PCB, there are several more small screws that need to be removed.

Finding a track to destroy

In order for the switch to be able to physically disconnect the battery off circuit, we will need to destroy at least one track on the PCB. In both my cases, there was a single track coming out from the positive terminal, and this is what I "destroyed".

To make the separation, I used my utility knife and I also used it to grind off a bit from the solder mask on the terminated side. This is where we will be soldering the wires for the switch.

Adding the switch in circuit

For the switch wires, I used the thinnest wire I could find, 0.1mm in diameter. This came from an old LED bulb transformer and it is important that this wire is isolated.

I stripped a bit of the insulation on one end with the utility knife and I soldered that end to the positive terminal and another such wire to the exposed track from before.

I then routed the wires to the exterior of the plastic enclosure so that I can solder them to the switch. The switch is then secured with a drop of super glue to the exterior and we can call the modification done.

Next Steps

There are several mods online that go far and beyond of what I did and include a rechargeable battery, a better case for the switch and a lot more, but for what I needed this is just perfect. The CR2032 battery will last a long time when it is kept disconnected so my goal is complete there. If you are interested in seeing some other mods, please let me know in the comments.

Tools and materials

Below are links to some of the tools and materials I used for the project. By purchasing through them, you support me and my channel at no extra cost for you!

• Digital Calipers - https://s.click.aliexpress.com/e/_mMuASQR
• Latching PCB Switch - https://s.click.aliexpress.com/e/_EyHCGmp
• Slide Switch - https://s.click.aliexpress.com/e/_EG4Qb41
• Multimeter - https://s.click.aliexpress.com/e/_EyU3gWD
• Grinding Pen - https://s.click.aliexpress.com/e/_EwGGpnR
• Soldering Station - https://s.click.aliexpress.com/e/_EyFoM6t
• Screwdriver Repair Set - https://s.click.aliexpress.com/e/_ExFREGl