Lithium coin cells (batteries) are very popular for timekeeping and memory backup applications. Ever wonder why?

Fast facts

The output voltage is 3 V, roughly double that of other common battery types. Designers can use one lithium coin cell instead of two cells of other chemistries.

Let’s take a stroll down Random Access Memory Lane to see how controller memory evolved over the years.

Let’s take a then-and-now look at how generations of S-COM controllers kept time.

The term for what we’re talking about is Real-Time Clock, or RTC. It refers to timekeeping in human terms (time and date) rather than the cyclical clock signal used to synchronize logic. RTC can be implemented in software or with an integrated circuit that tracks time and date independently of microprocessor intervention.

Today, most repeaters are available with internal controllers. This presents the owner with a choice: Do I retain the internal controller, or add an external one at extra cost? Let’s look at the differences and some reasons for upgrading to a larger model.

If you own a 7330, you know that its flexibility in port programming is unmatched in repeater controllers.

How did it get that way? Let’s go back some years...

The 7K is in its prime and is our flagship model. It’s designed to support one repeater, one link transceiver, and one control receiver. It’s still doing its job well, but we’re getting more frequent requests to have it control two or three repeaters instead.

So why are we dedicating a blog to a boring topic like cabinets? Are they made of Valyrian steel?

Nope, aluminum. But we hope you’ll find the details interesting anyway.

Our repeater controller cabinets are made of 5052-H32 aluminum alloy sheet. It’s strong, light, formable, and commonly used for aircraft, marine, and commercial-grade parts.

Macro commands have been implemented in every S-COM controller since 1976. Why?

The term dates from mid-1950s computing. It was common for a programmer to enter a short macro instruction to generate a series of other instructions. It saved time, reduced errors, and helped standardize the code.

So where did it come from, anyway?

Not surprisingly, early repeater control systems weren’t very sophisticated by today’s standards. Oldsters will recall one-tube COR circuits, CW identifiers that used code wheels and tape decks, and controllers made from relays and pneumatic timers. Some repeaters could be shut down by dialing an unlisted telephone number.

The 7330’s internal power supply is compatible with both standard and alternative energy sources. Here’s how it works.

The 7330’s circuitry requires four voltages: +5 V, +3.3 V, +2.5 V, and +1.2 V. A type of DC/DC converter called a buck regulator reduces the external supply voltage to +5 V; linear regulators further reduce +5 V to the other voltages.