Hello.
These on the control panel of kitchen ranges work by duty cycle, Is there several types of these ?


Am looking for one that its tiny internal heater makes the internal bi-metal switch cycling without any 'burner plate' load connected. Do you know of a brand/model/part number ? If at 120VAC, better.
In other words, the click-clack (on-off) times vary by the shaft position.

Perhaps the control in this thing has an internal heating ? Anyone knows ?

 

The control you want is a simmerstat.

 

The dial on my stove is like that, I believe. No thermostat on the burners, just control by duty cycle determined within the guts of the switch. I have no idea if mine works without a load, though.

Pretty sure this is mine: https://www.robertshaw.com/Products/Cooking/Infinite-Switches/5500-200/?cat=2147483735

 

This is a mechanical thermostat with hysteresis. What is infinite about it? The resolution of the temperature setting?
The duty cycle results from the hysteresis of the switch and the thermal properties of the thing that is being heated (thermal mass, insulation, etc).

 

With no more description than what is given there is no way to offer much advice. Variable duty cycle timers are available but as we are not even given an operating voltage there is no way to suggest anything.
Thus the TS needs to provide a lot more description of what the actual application is.
Otherwise there is no reason to waste time guessing what might work.

 

The ones depicted in the OP appear to be typical of 'Infinite' control switches, these use a bi-metal strip connection across terminals that disconnects with increased temperature as depicted in post #3.
They are still fairly common.

 

The ones depicted in the OP appear to be typical of 'Infinite' control switches, these use a bi-metal strip connection across terminals that disconnects with increased temperature as depicted in post #3.
They are still fairly common.

It is not likely that a bimetal switch type of variable duty cycle controller will function with no load, although it is possible if it includes a full voltage heater, The question is about the application.

 

My read of this patent is that the internal heater runs in parallel to the external load. But it is a bit confusing.
https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/11566793

 

It is not likely that a bimetal switch type of variable duty cycle controller will function with no load, although it is possible if it includes a full voltage heater, The question is about the application.

The picture represented in the OP appears to be the type that is typically aimed at a wide range of wattage control, 100w to 3600w, these are usually used in 240v element controls with the neutral supplying an internal element for the bi-metal strip.
IOW the Bi-Metal element circuit is separate to the intended load.

 

With the heater across the contacts it only requires the two connections, making the application a bit cheaper.

 

My read of this patent is that the internal heater runs in parallel to the external load. But it is a bit confusing.
https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/11566793

Exact control as meant, surprisingly recent patent. The internal parallel heating does it. Now will have to find who manufactures such. Thanks, Wayneh.

Dismantled a couple of different stove controls and there is no ´heater´ in them. Seems a bimetal gets hot by being a non-copper poorly conductive path in series with the hot plate load.
Dismantled a single plate stove as the second image and senses heat from proximity to its hot plate.

 

Certainly there are a variety of schemes for producing a variable ON/OFF duty cycle, including "heat while contacts closed", "heat while contacts open", and "heat while load is drawing current."Within each scheme it seems there is also both independently powered and load supply powered versions. And all of this in a electro-mechanical bimetal motivated variable duty cycle package. So there is bound to be a bit of confusion arising. While these different arrangements are able to control an electric stove temperature, none of them will function as a satisfactory light dimmer. I discovered that many years back when I tried to dim a light with one of them. I was in fifth grade at the time and did like to make electrical projects. batteries were expensive but mains power was readily available for free (to me, at home) and so things were mains powered, mostly.

 

This is a nice one with infinite control :
The code is available on the Microchip site.

 

The older ones I've taken apart have a thin nichromium wire (or some other metal) that run across the neutral and line/load circuit. Regardless of whether there's a load or not the switch operates based on how much pressure you put on the bi-metalic junction. More pressure means longer heat cycle. Cool time does not change (relatively speaking). The cycle times can run anywhere from short seconds to longer minutes of on time. Since the heating element on the stove doesn't respond very quickly a slow cycle time works just fine.

 

I checked a Simmerstat yesterday. There is a 12Ω heating element in series with the load: so not what you're looking for

 

The older ones I've taken apart have a thin nichromium wire (or some other metal) that run across the neutral and line/load circuit. Regardless of whether there's a load or not the switch operates based on how much pressure you put on the bi-metalic junction.

This type is still in use, as shown in the OP.;
Many modern stoves now use a form of electronic control. I just discovered mine had calibration method for the oven !!

 

Used to have gas stove. Now have induction stove with electric oven. And solar.

 

Gas? Still do, still popular.!
68% of US household's owns one.!

 

Exact control as meant, surprisingly recent patent.

FWIW, the patent seems to describe the similar switch in my 30-yr-old stove. I didn't get to the claims, which might make clear what's truly new and novel in this particular patent. There may not be much. It's a well known strategy to keep patenting every aspect of innovation around your bread and butter product, to keep extending the coverage as long as possible. Anyway, glad it helped.

 

Gas? Still do, still popular.!
68% of US household's owns one.!

The "E X P E R T S" are saying running a gas stove in the house is hazardous to our health. Funny, I grew up in a home with a floor gas heater. Did not have a flue. Heat and exhaust gasses entered right into the home. Today the experts would be screaming about carbon monoxide. In fact, in the mornings I used to stand on the register and feel the warm heat rising up. Every morning. Never mind chewing on lead paint chips - I stood directly in the exhaust stream. I may be small for my age but I'm still as sharp as a fuzzy tennis ball.