Line voltage thermostats

If you have an original Eichler, this might be interesting to you.

There are two kinds of thermostats: 24 volts, a.k.a. "millivolt"; and baseboard, a.k.a. line voltage. The former is the sensible kind: the heater takes a low-voltage signal from the thermostat to determine whether to turn on. The latter is silly: the signal wires operate at the full voltage and current of the heating system, so when you adjust your thermostat, you're one insulating plate away from the trillion watts coursing through the heater.

The sensible kind has seen all sorts of great innovations with the advent of microelectronics, such as this:

Look at all those buttons. I wonder what they all do. Meanwhile, the line voltage thermostat industry's efforts in the 60 years since the last world war have brought us this gem:

Guess which kind is used in Eichlers.

Anyway, if you want the new gadget-type thermostat but don't want to spend thousands to put in a new central heating system to get it, then what you want is a neat contraption that acts as a relay between the high-voltage heater and any old millivolt thermostat. The neat part (since the relay needs a nontrivial amount of power to work the magnet) is it also has a little built-in transformer, so it's pretty much self-contained. Wow!