Here are some unusual uses for common electrical devices:

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A Feet Heater

The concrete floor was cold, so I wanted a heater to keep my feet warm under a workbench. I tried a standard portable heater, but it had two problems:

  1. The standard heater's thermostat alternately roasted and froze my feet.
  2. The standard heater could not be used when I used the soldering iron at the same workbench or the circuit breaker would trip.

The problem is that nobody sells a heater that puts out less than 500 watts. So I made one:

The calculations I used are as follows:

Calculations at 240 Volts:

500 W / 240 V = 2.0833 A

240 V / 2.0833 A = 115.2 Ω

Calculations at 120 Volts:

120 V / 115.2 Ω = 1.0417 A

120 V × 1.0417 A = 125 W

I bought a 500 watt 240 volt baseboard heater and put a 120 volt plug on it, as shown at right. Make sure the hot wire goes to the thermal fuse.

The calculations show that the heater is now a 125 watt heater.

This heater does not draw enough current to cause problems when the soldering iron was in use.

The heater worked just as I wanted it without a thermostat.

When I later wanted to adjust this kind of heater's output, I found that an ordinary lamp dimmer worked quite well.

Because of the shape of the case, I had to put the heater upside down so it would set on the floor.

desk heater

Wiring diagram of a 240 V
500 W heater connected as
a 125 W 120 V heater

A Floor Warmer

The floor is cold in the house when the weather is colder outside, so I wanted a way to make the furnace run longer per cycle when the floor is cold, rather than having to monkey with the thermostat when the weather changes.

Calculations at 120 Volts:

10 W / 120 V = 0.0833 A

120 V / 0.0833 A = 1440 Ω

3 W / 120 V = 0.0025 A

120 V / 0.0025 A = 4800 Ω

Calculations at 24 Volts:

24 V / 1440 Ω = 0.0167 A

24 V × 0.0167 A = 0.4 W

24 V / 4800 Ω = 0.005 A

24 V × 0.005 A = 0.12 W

I bought a second thermostat and mounted it just above the baseboard at floor level. I used a Honeywell CT31 A1003 with a slotted cover over it to protect it from foot traffic. These thermostats must be simple thermostats, not electronic ones.

I connected the heat connections of the floor thermostat to the terminals across the anticipator heater of the other thermostat, as shown in the diagram.

The connection marked $ has no screw terminal and must be soldered. Also, cut the jumper at x.

The light bulb is optional. Its purpose is to make the anticipator on the floor thermostat operate. Use a 120 V bulb between 3 W and 10 W, and keep it away from the thermostats.

Set the floor thermostat 2 to 4 degrees below the setting on the wall thermostat.

Set the wall anticipator for normal operation. Set the floor anticipator experimentally to get the amount of extra heat needed.

To enable the floor thermostat, set its switch to HEAT.
To disable it, set its switch to OFF.

floor booster

The two switches shown
are ganged.

An Air Stirrer

The air in the house gets stratified. Also, the air needs to be run through the high efficiency filter periodically. The electric bill goes way up if the fan runs continuously. So I wanted a way to occasionally run the fan to stir the air, whether or not heat is needed.

Light Bulb at 120 Volts:

25 W / 120 V = 0.2083 A

120 V / 0.2083 A = 576 Ω

Calculations at 24 Volts:

24 V / 576 Ω = 0.0417 A

24 V × 0.0417 A = 1.0 W

I bought a thermostat and mounted it high on the wall (above normal wall level). I used a Honeywell CT31 A1003 with a slot cut in the bottom edge of the cover to admit heat from the light bulb mounted below it. These thermostats must be simple thermostats, not electronic ones.

Cut the jumper at x.

When enabled, this circuit cycles the system blower on and off. Adjustment of the anticipator and thermostat settings determines the cycle length and the duty cycle of the blower.

The lamp should be mounted in a metal enclosure directly under the thermostat. A 25 W 120 V lamp was used, but is operating on 24 volts. The top of the enclosure must be open

To enable the stir thermostat, set its switch to HEAT.
To disable it, set its switch to OFF.

stir control

The two switches shown
are ganged.

Traffic-Actuated Stairway Lighting

I wanted to make stairway lighting in my home automatic. The lights come on only when someone is actually using the stairs.

I bought two outdoor motion detector floodlights to use as detectors. They must be the kind that uses a relay to turn on the lights and uses screw shell bulbs. I mounted one at each end of the stairs. If the stairway has a landing between flights, additional detectors can be wired in. This can also be used in a long hallway or on a ramp.

Lights can be connected in anywhere along the run. But the total wattage must be smaller than the capacity of any one of the detector units.

I later had to add a switch (shown) to turn off the lights in the event that a power surge caused the lights to stay on. Turning the switch off for 5 minutes fixes it.

Aim the detectors so that the entire stairway and its approaches are covered by their sensory fields.

stairway lights

Black = 120 V Hot   White = Neutral
Red = Switched Lamp Power   Green = Ground (bare)

Timer Control of Air Conditioner

I had a heavy-duty electronic timer controlling a booster air conditioner. The problem was that the surge from the air conditioner starting or stopping erased the settings on the timer.

I bought an Intermatic 15A appliance timer to control the 500W air conditioner. Then I had to add the other parts to keep the surge from the air conditioner from erasing the settings on the timer. I put everything in a 2-gang handy box with 2 duplex outlets feeding the lamps and timer. The orange and black plugs and the orange socket are on cords.

The capacitors and the resistive incandescent lamps offset the inductive load of the air conditioner. This protects the electronics and the contact points from the surges from the air conditioner when it starts and stops.

I colored the outlet faces the indicated colors with permanent markers to prevent them from being used for other uses. The lamps are in plug-in screw sockets.

stairway lights

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LED Christmas Light Circuits

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Circuits for New Technology Bulbs

Circuits for New Technology Bulbs (scroll down)

Switching Circuits for Selecting Between Series and Parallel

Selecting Between Series and Parallel

Build Special Purpose Lamps

Build a Full Spectrum Lamp

Build a Lamp for Defective Color Vision

Simulate Defective Color Vision

My Inventions and Discoveries