Could you please tell us who made this old alarm sensor? It’s part of an alarm system that was professionally installed and we’ve debated whether to leave it in place after a panel upgrade.

A: It’s late 1980s, early SMD, looks well-made for the era and professionally installed with bridging detection, as well as triple pulse count and tamper detection. It’s in good condition – obviously installed in a dry environment. Probably has a genuine Fresnel lens, which is increasingly rare these days.

It’s up to you as to whether you pull the sensor and replace it, or add it to a new controller. If it was your own home you might keep it if the panel is compatible, but you don’t want to be called across town when the opportunity cost is only $35. The wiring in some of these images looks fine – we’d be tempted to trim that and use it again, all test measurements being equal.

We’re not sure who the maker was – the big brands of the time were Ness and EDM – if anyone with a long memory emails us more details at [email protected] we’ll add the information to this post.

* We’ve had a reply to this query from Greg Curry who says this sensor is a Gem PIR, manufactured by Micron NZ. According to Curry, these were excellent detectors and he installed many of them back in the day. 

Simon Jabour of Micron Alarms agrees.

“The detector in question is rightly called a GEM PIR, manufactured in New Zealand by Micron Alarm Supplies/Micron Security Products,” he says. “Yes, Gem was a 3 Pulse count detector and was fitted with a Fresnel lens. Mounted at the correct height of 2.4m it would detect intruders at up to 20m. If the components don’t break down in the installed environment, this detector will probably last another 10yrs.”

And from Peter Lind of DataTalk:

“Ahhhh, the good, old Micron GEM – Micron also famously manufactured the 6-Pac alarm panel. The 6-Pac was so good at the time that even Gallagher used it as their fence controller because “any decent security tech knows the 6-Pac, why not use it to control the electric fence?”

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