“Do you have hard-to-reach light bulbs? If so, then you are perhaps familiar with a device known as a Light Bulb Changer. It threads on the end of a pole and extends your reach. A problem is one of mechanics. If you can’t get your pole square to the bulb, the effectiveness of the holder decreases rapidly. Imagine trying to use this thing at a 90 degree angle to the bulb. That is the exact situation I found myself in.
OK. Just get a tall ladder, move that table, make that suspicious call confirming my life insurance details and up I go. Just kidding, I instead used this as an excuse for another maker project.
I spent way more time on this than the ladder would have taken. Then again, it was quite a bit of fun and now I have a useful tool on-hand ready to square off against the next light bulb challenge. Lucky for you, all of the design, modeling, and testing steps are done so you can build one in a fraction of the time.
Of course if you want extra challenge, feel free to mod up the design below to match your favorite parts and techniques. Have it play inspirational music, add Bluetooth… Your imagination, skill, time and budget are your only limits.
If you don’t have a 3D printer, hope is not lost. You can always use a project box, parts from the hardware store and plenty of zip ties to get things done old school.
Parts I used include:
- Geared brushed motor. These are around $13 on Amazon, probably cheaper other places. I went with 200 RPM which is a bit more than 3 rotations/second at 12V. This seemed about right.
- Flange Coupling Connector. This is needed to adapt the motor’s shaft to the Light Bulb Changer.
- Microcontroller. I went with the ATTiny85 which cost $1-$2. Loading firmware on it can be tricky if you have not done so before, but there are dozens of video and written guides on the internet on how to do it. Once you get it working the first time, it will be turn-key after that.
- L293D H-bridge motor driver. This turns the puny waveforms the ATTiny85 can generate into power boosted energy waves that can drive a motor at variable speeds and in either forward or reverse.
- Broomstick or painters pole for mounting
- Wire to connect the control box at one end of the pole to the motor at the other.
- Zipties to secure the control module to the broomstick.
- Sony PS2 thumbstick which is basically a thumb-friendly potentiometer. Any 10k potentiometer will work, so long as you are OK with the ergonomics.
- A power source. You’ll need around 12V and enough current to drive the motor. A 3S lipo battery (450-1800 mAh) works well, but you’ll need a special charger if you don’t already have one. You can also stack 9 (or more) AA batteries in series. A 12V DC “wall wart” could also work.
- Connectors for the power source. With a small 3S LIPO, I really like the XT30 connector.
- PCB prototyping board. Technically optional as there are many ways to construct a circuit, but a 30x70 perf board is what I used.
- Status LEDs. I went with a two-color LED which has red and green channels. You can also go with two separate LEDs of any color you want.
- Some current limiting resistors for the LEDs. Values are not critical - something in the 470 to 2k range will work.
- A 5V regulator. I went with the LP2950Z but nearly anything will work here.
- Some capacitors. The DC motor is a noisy load for the battery and the 5V regulator will see this noise on it’s input. Caps on each side of the regulator will help reduce this noise to the 5V electronics. I went with 500+ uF on the input side and another 100 uF on the output side, which is likely overkill.
- Connectors for the PS2 thumbstick and motor wire. I used standard 2.54mm pitch headers. Anything you have could work.
- A 3D printer if you want print the motor housing and controller box. As said above, you can also come up with a custom alternate solution.
- A Breadboard. if you want to verify operation before committing the parts with solder.”