High tech comes to Am Sci & Surp!! It is here in the form of a Peltier junction, a thermo-electric device that translates electric power into heat, and perversely, into cool. Apply current @ 3-12 VDC to the gizmo and it extracts thermal energy from one face, thereby cooling it. The heat is dumped onto the other face, thereby heating it. Please note: you must use a heat sink on the hot side or the junction will fry itself, since it can quickly create a 65° C temperature differential in a no load situation. Stack two, or build a cascade to increase the thermal differential created. Or run it backwards. Apply heat or cold to the relevant face and produce a current. Amazing for science projects and experiments. Practical for coffee warmers, beer coolers and mini-refrigerator or warming oven applications. Comes with instructions. Large is 1-9/16" sq. x 3/16" thick.

From Therm-O-Disc, this thermal cut-off switch is N/C (normally closed) by definition. (Thermal cut-offs are what keep your coffeepot from burning your house down.) This one shuts down between 221°F (105°C) and 248°F (120°C) and measures 5/8" dia x 9/16" thick, with (2) axial terminals.

It's a nonpolarized bimetal heat sensor, 1/2" long with rubber sleeves and 6" long leads. It's also mysterious, because when used as a thermocouple multimeter input, it reads approx 94° in nearly boiling water but approx 170° in ambient air. Wethinks some sort of inversion or scaling is going on, but a person with your smarts will surely figure it out.

This 120V 1385W J-shaped heating element hit 750 degrees before it scorched our test bench, so we turned it off before it burned the place down. Measures 8-1/4" long x 1-5/8" wide across the elements x 5/16" with 1/4" terminals past threaded ends. We believe these were made to live inside hot-water heaters. UL recognized.

Dry heat is for deserts. This handy little non-electronic humidifier is made to keep you from drying out in the living room this winter. It’s simple, really, just a 10” x 7” x 2-1/4” thick white plastic frame with little feet holding a hunk of open-cell foam that you soak with water and place on a register vent, radiator or in front of a baseboard heater. Presto, instant humidity.

You need a dehumidistat to sense the relative humidity and turn on a fan or whatever dehumidifies you. This one is from Broan-NuTone and is rated for up to a 10A load at 120VAC and 5A at 240VAC but can be used with a low-voltage (24V or less) fan. Use the clearly marked, easy-to-use dial to set your humidity anywhere from 20 to 80 percent, with full on and off settings as well. Housing measures 4-1/2” x 2-3/4” x 1-1/2” with keyed 5/32” mounting holes. Comes with mounting hardware, Lo-V terminals and wiring instructions. Made in Canada by humid Canadians. Broan #DH100W.

It’s a Peltier junction rated at 12VDC, 2.2 Amps, and attached to a heat sink and a muffin fan, making it all a self-contained cooling unit measuring 1-9/16” x 2-3/16” x 3-1/4”. Techie talk: the fat red & black leads are for the Peltier; thinner ones feed the fan, and there’s a yellow or white thermal sensor lead on the same plug. Separate green and yellow leads are to the thermistors at the top of the cool side of the heat sink. Made in the USA.

Return with us now to those thrilling days of 1977, which is when this Pyrex-topped heating element was made as part of a stovetop hotplate. Measures 10-3/8” x 5-3/8” x 3/16” thick, and draws 120W at 120VAC with a thermal cutoff, neon indicator lamp, 1.5 ohm power resistors on both legs as fuses, and 4-1/2” leads. Will heat up to at least 230F. Made in the USA by Sierracin/Thermal Systems, part #976-4935-3.