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Step 1: Parts Used
Here are the parts I used in this project
1. 5 inches of 0.01" 70 degree Nitinol wire
2. A 5 volt power supply .5 amps (this can be replaced with a usb cable)
3. A small wood box from a craft store
4. Two ring lugs
5. Two 3mm counter sink screws and nuts
6. Two plastic wire ties
7. Some 30 AWG hookup wire
8. Super glue
9. A small piece of balsa wood.
10. A 2K resistor and a TIP31 NPN Transistor
11. A 555 timer kit
Step 2: Assemble the Electronics
Assemble the 555 timer kit according to the instructions but do not install the relay that came with the kit. Install the 2K resistor and transistor like the schematic below shows.
Step 3: Make the Nitinol Actuator
1. Crimp a ring lug on each end of the Nitinol wire.
2. Wrap the wire around a nail or other metal rod and use a small piece of 30 awg wire to hold the Nitinol wire in place.
3. Heat the Nitinol wire in an open flame. This will reset the memory of the Nitinol and turn it into a spring shape.
4. Remove the Nitinol from the nail and solder a 6" piece of 30 awg wire to each ring lug
Step 4: Prepare the Wood Box
The box I bought has a fine wire mesh inlay on the lid
1. Cut a slot in the wire mesh so the screw on slider won't be obstructed.
2. Glue the head of a screw on the underside of the lid. This is were you will attach one end of the actuator.
3. Drill a small hole in the back of the box for big enough for the power cord to fit in.
Step 5: Make the Balsa Wood Slider
1. Cut a piece of balsa wood that fits loosely from front to back in the inlay and is about 1/2" shorter than the inlay side to side.
2. Glue the head of a screw to the back side of the wood slider. Make sure it lines up with the slot in the mesh inlay of the lid.
When the balsa wood slider is placed in the inlay make sure it slides it back and forth easily with very little resistance.
Step 6: Make the Return Spring
The return spring is made out of a used plastic wire tie.
1. Use a straight pin to poke a hole in each end of the wire tie.
2. Put a short piece of 30 awg wire through each end and make a loop big enough to fit over your screws.
Step 7: Assemble Lid Parts
1. Install the slider in the lid and attach the spring to the two screws.
2. Install the actuator on the two screws and bolt them down.
Step 8: Install the Timer Board
1. Install the timer board inside the box.
2. Feed the power cord through the hole you made in the back of the box and connect it to the timer board.
3. Attach a plastic wire tie to the power cord to prevent it from being pulled out of the box.
Step 9: Adjustments
1. Adjust the pulse pot on the timer board so power is applied to the actuator only long enough to fully move the slider to one side.
2. Adjust the pause pot so the slider only moves around every two minutes. I adjusted it faster for the video.
3. Shim the wood slider so it is even with the top of the box.