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Thermostatic Electric Iron
The electric flat-iron already published has one state: on. Leave it plugged in and it keeps getting hotter until something scorches - the user is the thermostat. The rung above it puts the Butz idea, a bimetallic strip, inside the iron: the iron holds whatever temperature the dial asks for, and silk and linen each get their own.
**US 2,723,336**, "Thermostatically controlled electric flatiron or the like", Swenson and Finlayson, assigned to General Electric, filed 23. July 1953, granted 8. November 1955.
**You build the thermostat, not the mains appliance**: a bimetallic strip switching a battery-powered lamp, measured on a hotplate - then you measure a real iron's cycling from the outside.
Beginner
2 hours
Instructions
1
1
A switch from a strip
A switch from a strip
Clamp one end of the bimetallic strip. Set a screw or a stiff wire as the contact so the free end presses it at room temperature. Wire strip and contact in series with the LED, its resistor and the battery holder: the lamp is on while they touch.
Materials for this step:
Bimetallic Strip1 piece
LED - Basic 5mm1 piece
Resistor Kit1 kit
Dupont Jumper Wire Set (M-F)1 setTools needed:
AA Battery Holder (4-Cell)
Spring Clamp2
2
Heat it and watch
Heat it and watch
Tape the thermocouple to the strip. Warm it gently on the hotplate and note the temperature when the lamp goes out; let it cool and note when it lights again. Three runs.
Tools needed:
Hot Plate
Thermocouple with Readout
Clear Safety Glasses3
3
Move the contact
Move the contact
Turn the contact screw in by half a turn so the strip must bend further, and repeat. That screw is the iron's fabric dial.
Tools needed:
Thermocouple with Readout4
4
Measure a real iron
Measure a real iron
Stand a steam iron on its heel on a heatproof surface at a mid setting. With the infrared thermometer on the soleplate and a stopwatch, time how long its indicator lamp stays on and off over several cycles, and note the highest and lowest readings.
Tools needed:
Steam Iron
Infrared Thermometer
Stopwatch5
5
Bend, hysteresis, duty cycle
Bend, hysteresis, duty cycle
Loading Jupyter Notebook...
6
6
History & Context
History & Context
**What the patent specifies:** a flatiron whose heating element is switched by a thermostat set from a fabric dial, holding the soleplate at the chosen temperature. **Modern build (derived):** the bimetal switch alone, on safe low voltage, plus outside measurements of a working iron.
The same bimetal switch went into kettles, ovens, toasters and motor overload protectors. Its limits: the strip switches over a few degrees of swing, it ages with cycling, and it senses its own temperature - not the cloth's.
Materials
4- 1 piecePlaceholder
- LED - Basic 5mm10% commission1 piece$0.77
- from$5.70
- Placeholder
Tools Required
8- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Steam Iron10% commissionPlaceholder
- Placeholder
- Placeholder
Estimated Total
What the maker bought. Materials shown without a price are sourced wherever you buy them.
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