Ancient RF teardown: crude but effective

August 01, 2015 // By Bill Schweber
Bill Schweber tears down an old Telectron garage door remote control and finds it elegant as well as more analog than digital.

We now view the convenience of sophisticated home-automation systems with their smartphone-enabled, Internet-connected functions such as garage door control as "routine." It wasn't always so, of course, but smart engineers worked some design magic with far fewer options, yet still did clever work.

This became clear to me when I came across an old garage-door remote control by Telectron, also called a clicker, see Figure 1.

It has no date markings, but I estimate it is 30 to 40 years old, based on the design and asking some questions of family members. There's no indication of frequency, but due to the "Model No. T80--RF 230" designation on the back, and some similar units I found on the web, I assume it's a 230MHz unit. The package is 10 cm by 5.5 cm by 2.5 cm thick and has only one user control, a large square push-button which actives a small switch on the PC board. It's the genuine embodiment of simplicity of operation, that's for sure.

Figure 1: Garage-door opener is a model of simplicity in design and use; it has just one user button, with a large arrow molded into it.

Compared to today's RF units which operate from 900 MHz for a basic dedicated unit to 2.4 GHz and higher for a smartphone connection, it is both easy and tempting to dismiss the design of this RF unit as trivial. However, the available parts were larger, design and layout tools were non-existent, and units like these had to be very, very inexpensive.