Build A Motion Sensing LED Step Stool

This is a fun project that can be built in a couple of hours (minus the glue’s drying time).

Building a step stool is obviously a simple project. The circuit is also extremely simple but it can be used to drive robot motors, water pumps, or high voltage lights from a Raspberry Pi or Arduino.

Parts

2N2222 transistor
PIR sensor
LED Strips
1/4 inch neodymium magnets
5-minute clear epoxy
20 gauge flexible wire
2 x 4-AA battery holder

The Wood

Here are the rough dimensions of the wood, but these measurements were taken after the project was finished.

The top was 12″ by 7″
The total height was 7″
The width of the bottom of the leg was 8″
The legs were splayed out at a 10-degree angle.

The only measurement that’s important is the ratio of the top platform to the base. Make the base about an inch longer and wider than the top so it won’t tip over. Decide how big you want the top then cut the legs accordingly.

The Cross Beams

The center cross beam is made from three parts, the center beam, and two pieces that are attached to either side of the center beam.

Carve out the middle of the center beam and cut tenons on the ends.

Use the center cross beam as a pattern for the other two. Cut a mortise in these, but don’t cut all the way through. When the three pieces are placed together, there should be a hollow center.

The Step Stool

Glue all the joints and clamp everything. Only glue one side of the center beam. The other side will be the access panel used to install the electronics and change the batteries.

After the glue dries apply whatever finish you want. I don’t really like stains, so I just used a simple oil finish.

The Access Panel

Drill small recesses on the inside of the center cross beam and loose cross beam.

Mount the magnets in the holes with epoxy.

The Circuit

Attach the LED strip to the center cross beam. Drill a small hole at one end large enough for a red and black wire. Solder the wires to the led strip and cover the exposed solder with some hot glue.

Measure the diameter of the PIR sensor and drill a hole through the center of the cross beam covers. Screw or hot glue the sensors in place.

Solder the parts together as shown in this diagram

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