You will need: RC car, watch batteries, buzzer, wire, LEDs, seltzer tablet, universal AC adapter.
Inexpensive radio-controlled cars have many sneaky adaptation possibilities. We’ll use the cheap single-function type of radio-controlled toy car — the type that continuously travels forward once it’s turned on until you actuate its remote control, causing it to back up and turn. You can modify the transmitter to a more compact size, and for use as an alarm trigger. You’ll also modify the receiver to activate other devices, such as lights and buzzers.
1. The transmitter is always in the Off mode until its activator button is pressed or until wires connected across the push-button leads are connected together.
The first step is to remove the circuit board from the case. Then, substitute lightweight watch batteries for its normal battery type. For each AA or AAA battery, use one small 1½-volt watch battery to supply the same voltage output.
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2. Remove the radio receiver
from the car’s chassis.
Unlike the transmitter, the
receiver must stay On in order
to operate. You can use an AC
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voltage) instead.
The car motor is attached to the receiver with two wires. If you disconnect the motor wires, the receiver can be used for more practical purposes to indicate that a remote sensor is activated. LEDs and buzzers are perfect.
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3. If you connect two wires across the transmitter’s activator button, you can have another sensor or switch activate the transmitter to alert you of an entry breach or that your valuables are being removed, or that your basement is flooding.
Here, two paper clips are attached to the wires. Then, a seltzer tablet is placed between the paper clips with a rubber band. If water gets near the wires, the tablet will dissolve and the rubber band will cause the paper clips to make contact and activate the transmitter.
Illustrations by Mark Frauenfelder
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Cy Tymony ( sneakyuses.com) is a Los Angeles-based writer and is the author of Sneakier Uses for Everyday Things.
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