baby triac

Hotplate imperfection

I’ve got two hotplates and neither is exactly right.

  • lab hotplate with low power (300w), no power/temp control, and a 4” head that isn’t wide enough for pot stability. 300w is generally too little to cook over but too high for simmering
  • a no-frills IMUSA 1100w hotplate. 5.5” burner diameter works well with normal pots. Thermostat, but cycling nominal 1100w (measured 928w) off/on to hold a temp setpoint is more than my system likes. I did have a chance to use it on my recent stint on shore power.

thinking about solutions

Last time I looked the cheapest I found was $100. But now my searching is finding some controllers that seem to do what I want in the $25 range. Pertinent reviews/comments:

this works by chopping the AC cycles down to half the cycle of a full AC cycle. This WILL NOT lower the voltage or current! Do not use this on any electronics as it could damage it or greatly lessen the life of your electronics!

No problem, I’m just running resistance loads.

I used it this morning to control the heater element on my coffee maker - the coffee maker element is rated at 1440 W at 120V, and a Kill-a-watt registers 1420 from it. If set to non-variable mode the kill-a-watt registered 1410. When switched to variable, the output was as follows: at the lowest setting it output 687 W, at the middle of L it output 710, at the top of L: 750, at mid-M 812, at low H 955, and at the max the Kill-a-watt showed 1374 W. My desire was to reduce the output of the coffee maker to slow the brewing and it worked perfectly for that. The unit heats up whether in variable or non-variable mode, in variable mode it does get hotter, but not excessively in my opinion. Your mileage will likely vary..

That sounds really promising. Interpolating from the above, On the larger hotplate it appears wattage can be dropped as low as 449w. I’m thinking the IMUSA’s 5.5” coils running at ~500w-600w would be verrah nice. Leave the thermostat cranked all the way up and use the controller to vary the heat.

Another review suggets there’s a pot to turn down the minimum even further:

I read another review that indicated there is a hidden adjustment potentiometer inside for minimum power setting. Wall dimmer switches have these as well. I was able to adjust it, but I’m waiting for my tachometer to get it where it needs to be. By the sound of the motor, I can tell it will go down enough. They really should disclose this adjustment in the instructions… Note: The hidden adjustment is soldered onto the top side of the PCB inside but you need to use a small flathead screwdriver to adjust it from the back after removing the back cover.

Down to 25% power would be nice.

Other possible uses: run the 300w hotplate at 150w for simmering. Run crockpot at varying power to control temp more precisely than HI/LO allows. Oh boy oh boy oh boy

I’ll have to wait until/if the 1000w PSW is returned, but this should be interesting.

pulled the trigger

I ordered this one which has over 2,000 reviews and some clueful reviewers. I’ll let you know what we find…