SensingRebuild shelfTest and identify
Tilt switch
Also called tip-over switch, mercury switch.
Heaters use a tip-over switch so they die when they fall over. Newer ones are a mechanical ball or a pendulum. Older ones are a glass capsule of mercury. Mercury goes to hazardous waste, intact, not into the parts bin.
If you are new to this category
A sensor reports a condition such as weight, light, temperature, or position. Many sensors do not switch fully on or off. A kitchen scale bar, for example, changes by thousandths of a volt. Keep the small board that read the sensor if you still have it.
Keep the connector. Write down the wire colors before you cut them. If you do not know which wire is which, the sensor is hard to reuse.
Red and black feed the sensor a steady few volts. Green and white are the tiny signal, measured between them, not from either one to ground. Pressing the bar changes that signal by millivolts. A normal meter on DC volts can show that it responds. Turning it into a number on a screen wants a small amplifier board, often an HX711.
Mercury. A broken CFL, fluorescent tube, or old tilt switch releases mercury. There is no useful parts yield that justifies breaking one.
Heaters without their cutout. Nichrome and tubular elements are happy to start a fire if the thermal fuse or tip-over switch is left out of the new circuit.
| What to look for | Usual figure |
|---|---|
| Mechanical | A ball bearing bridging two contacts, or a spring pendulum. Rated for the heater current if it was in series with the element. |
| Mercury | A glass vial with liquid metal. Do not break it. Do not collect it. |
Volts are electrical pressure, amps are how much current is flowing, and ohms are how hard the part resists that flow. A higher voltage than the part was built for is how salvage parts die on the bench. If a cell in the table says “read the stamp”, that stamp is the whole specification.
What people actually use it for
- A tip-over cutout on a new heater
- A crude motion alarm, mechanical types only
Leave this one when
It is mercury. The rest of the heater can still be salvaged around it.
Buying a new one is the better idea when
A mechanical tip-over switch sold for heaters, if you are building a heater. This is not a place to improvise.
How to tell if this one still works
Beep while you tilt. A heater switch should be closed when upright and open when on its side, or the reverse — map it before you trust it.
Tools you will want: Meter.
Words on this page
Short meanings, so the rest of the entry is readable if you are not already doing this every weekend.
- series
- Connected in a chain. Cells in series add their voltages. LEDs in series all go dark if one of them opens.
Where people actually find it
1 notes, most useful first. “Leave it” means the part is in that machine and you should not take it: it is dangerous, worn out, or only useful if you already know that exact repair.
| From | Call | How many | How often | Where it sits |
|---|---|---|---|---|
| Space heater | Worth it | 1 | usually | Bottom. |
- In this particular machine
- Mechanical ball, or mercury in old units.
- Where to look
- Bottom.
- How to get it out
- Mercury: do not break the capsule. Recycle that switch.
- The condition to expect
- Mechanical ones are worth keeping.