Reed switch selection

I have an Excalibur Grandmaster electronic chess purchased in 1997. The set is in good condition however one square does not register movement by the magnetic chess pieces. I suspect that the underlying reed switch is no longer operational. All other squares work fine.

I have noted that the switch has a 10mm glass core and is form A. I would like to replace switch but do not know specifications. They are not available in manual or parts list.


Hi markie,

Welcome to the Tech Forum.

There would be no way for us to know the specific specs of your particular reed switch, but here is a link to a number of them that are 10mm or less which might work. They are arranged from most to least sensitive.

All of these can handle at least 350mA switching current, which is almost certainly more than enough for your application. Some are more sensitive than others, so the sensing range would be dependent upon the strength of your magnets and the distance between the magnet and the switch. Depending on distance between adjacent squares and the strength of the magnets, it is also possible that a piece on an adjacent square could trigger one of these if it were too sensitive. You may have to experiment a little there.

I would start by finding those which look most similar, dimensionally, and then either select one somewhere in the middle of the sensitivity range (either the 15 ~ 20AT or 20 ~ 25AT range) or get a few of them with different sensitivity ranges to see which worked best.

Along with the advice that David posted, try to simulate the same orientation of the reed switch and the distance from the magnet, and then visually test some of your samples before soldering. This should at least eliminate the most extreme results where the sensitivity is much too high or low.

Even if this simulation doesn’t product an exact match, but the switch/magnet pairing is almost adequate, you might be able to adjust the reed switch distance just slightly to compensate for the difference once it’s soldered into place.

1 Like