So, the STAR TREK DOOR has been a slow, “back-burner” project for a while. Recently, I got a little time, so I sat down and figured out how to hook up the air valves to a set of relays, and control those relays with an Arduino.

Here’s a video overview of the physical doors themselves and how we plan to open and close them with air valves.

This is a joint project, working on this with my brother-in-law, Fred. The doors are between his garage and workshop. Fred has been working on the doors themselves, the wall and framing, and mechanical connections. I’ve been working on figuring out the software, controls, and electronic magic that will drive everything.

IMG_6655IMG_6610The physical doors themselves are done, except for paint. Fred has also been making a pretty neat frame for the garage side. He cut alternating widths of wood and then glued them together for the nice light-colored wood on the inset of the planks that will frame out either side of the door. A similar piece will cross the top of the door.

I got all the main components – Arduino, breadboard, relay board, 12V power fuse panel, and air valves themselves all screwed to a piece of plywood. At this point, it’s not pretty, but it is functional.

IMG_6652We have a nice industrial door control with OPEN/CLOSE/STOP buttons on it. Those are momentary on buttons, but through the power of the Arduino, I can make them be whatever I want. I started with a Button Tutorial, and then modified it to suit my purposes, and added a Delay(1500) command after activating the air valve. That way, the valve will stay open long enough to fully open or close the door, even if the button is just pressed for a moment.

I programmed the pin for the STOP button to test out a sequence to open the door, pause (long enough for a person to walk though,) and then close the door. It seemed to work pretty well. If the timing is wrong for the real-world application, all I have to do is simply change the delay times. (It will also need a safety. We don’t want the door closing on a person!)

IMG_6520At this point, the basics of the control panel are working. The STOP button is just wired up as a “stand-in” for a single button we already have installed on the garage side of the door. It’s a capacitive touch button that lights up either blue or white with internal LEDs. It’s a neat looking button, but it’s only a SINGLE button. So, it needs to have functionality to both open AND close the door. I’d also like to explore using a variable in the Arduino that states whether or not the door is open, and then changes the functionality of that button based on whether the door is open or not. The air cylinders themselves also have built-in position sensors, which would be neat to use possibly as both a safety AND a “Is the door open or not?” sensor.

Here’s a video clip showing all the components actually working together. At this point, if the panel was simply mounted above the door, and air connected between the compressor and air cylinders, we would actually have functioning doors.

IMG_6653I don’t like the look of how the air valves and tees are held together right now. I was able to find some not-too-expensive push connectors (similar to PEX Sharkbite style) for air, which might make it a little easier to connect all the air components and look cleaner. Once I really have everything finalized on what’s going on at the breadboard, I also need to decide if I want to pull the breadboard out and replace it with a custom circuit  board. One thing I DO need is a simple way to connect the tiny pin connectors to the larger wires going to the buttons AND provide strain relief. For the moment, I just used staples to nail the 18 ga lamp cord wire to the plywood and then made the electric connection with alligator clips. What would be the BEST/CLEANEST way to do this? Some sort of small screw down terminals?

I also have a rather large fuse panel mounted on the plywood. It was free, and I already had it. It supports many separate circuits, but for this project, a single DC fuse would probably be fine. I’m also using a bit of an overkill 12V power supply. I’ll want to replace that with a simple wall-wart. Lastly, the Arduino is running from USB power. I’ll need to solder up a 12V DC barrel connector so that it can run off the same power as everything else. I think we will make a switched electric outlet, and plug the wall-wart in to that. If the system is ever not working right, just switch off the power and manually open and close the door as needed.

I’ll definitely want to hang out with the guys at the Makerspace sometime soon talking Arduino, specifically how to integrate some more sensors and get feedback used to activate the doors fully automatically.

-Ben Nelson

Video Wall of Terror

This weekend, I helped decorate for a Halloween Party at my sister’s house. There’s an odd hallway that connects their main large public room to the rest of the house. It’s used for storage, and has shelves on both sides.

This year, I decided to decorate that area by creating a video wall effect. Something like a Television Control Room of Terror!

To start with, I simply filmed my brother-in-law with a video camera – only from WAY TOO CLOSE! I shot macro video of his eye and mouth. Then I edited the footage to create a custom looping DVD.

In the hallway, I set up multiple monitors. These are old monochrome standard definition monitors that were on their way to the recycling center. They were professional monitors, which means that they can pass a video signal through from one monitor to another, making it easy to daisy chain several monitors.

Next to the monitors, I set up three DVD players (including one car DVD player – hey I use what I got!) to play the three different custom DVDs – Right Eye, Left Eye, and Mouth. Each of the three videos is a different length, so they will continue to drift out of sync. That way, as they loop, the visuals are a continuingly changing experience through the whole evening.

Above the monitors, I set up a video camera on a tripod and fed it to some of the monitors. That way, when party-goers look at the monitor, they also see themselves. Having feedback on some of the monitors adds a sense of interactivity to the project.

After the monitors and DVD players were all set up, I covered the rest of the shelving with black paper. In a dark hallway, lit only be black lights, it’s a great effect of creepy images floating in the hall.

If you want more details on this project, I made a full step-by-step write-up on Instructables.

Electric Ice Scooter


When I recently was at the thrift store and saw a pair of ice skates next to a kick-scooter, it got my mind going. “What would a scooter look like with skates in place of wheels!?”

The next time I was at the Makerspace, I saw my old electric scooter over on the Hack Rack. This was a scooter I originally rescued from a dumpster. Although it didn’t have batteries, just adding power and a little tinkering got it up and running again. A few of the EV Club and PowerWheels Racing guys played around with the scooter a bit, but eventually the controller got toasted, and who knows what happened to the front wheel.

Oh well, I’d be replacing that front wheel with an ice skate anyways.

Turns out that the heel of an ice skate is actually sturdy enough to drill right through and use as a mounting point. I simply  drilled through the skate, inserted a spacer, and then ran a 3/8″ bolt through the skate and the front fork of the scooter. I finished it off with a couple of washers and a nut.

Then next thing to fix was to get the  motor going again. Turns out that it’s a brushless motor. While I have a fair amount of experience now with BRUSHED motors, this was my first experience with brushless. I did a little research, and then ordered a 24V, 250 watt generic brushless controller from a mail-order scooter parts company. Unfortunately, it used a different style of throttle than what was already on the scooter, so I had to order a throttle to match.

Connecting the controller was pretty easy, three wires to the motor and the black and red one to power. I first bench-tested it with an old printer power supply, and once everything was working right, bit the bullet and bought a brand new pair of 12ah SLA batteries. The two batteries are wired in series, along with a 20 amp fuse, and then go to the controller.

I still needed a deck for the scooter. I dug through some scrap materials and found a pair of cabinet doors that were about the right size. I cut them down just a bit and bolted them to the scooter. I even re-mounted a cabinet door handle to have as an attachment point for towing a sled.

With that, I was ready to go for a test ride, so it was off to the lake. Once I was on the ice, I turned on the scooter and gave it a go! What fun! It really zipped along, but it was almost impossible to steer, as the back tire would slip right out from under me! Time for more traction!

I decided to make a spiked tire. I removed the rear wheel, then disassembled the two-part rim and removed the tire and inner tube. I stuck 1/2″ self-tapping, pan-head, sheet-metal screws through the tire from the inside, so that their points stuck out.DSC_0394 I evenly spaced out 24 screws and alternated them to be slightly off-center side to side. Next, I put some old scrap bicycle inner tube over them as a liner to protect the scooter tire inner-tube. After that, it was just a matter of reassembling everything.

Now for test #2 out  on the ice. Remembering how much it hurt to fall on the ice, I was prepared this time by wearing my motorcycle jacket (which has padding built-in) and my helmet. Good thing too, as I would learn while steering with one hand and holding a GoPro camera in the other…. (Note to self, keep both hands on handlebars at all times.)

Overall, the Ice Scooter works great! I still have a few little things to do on it. For example, the motor is running “sensor less”, and I’d like to learn about how brushless motors use the sensor system. I’d also like to get a small 24V dedicated charger. As it is right now, I have to remove the deck and manually charge with a little 12V charger.

From thrift store idea, to hack rack, to life on the ice, it’s always fun to see what you can do with just a little ingenuity. I hope you like this project. If you want to see more on it, please check out the write-up I did on Instructables. It’s even in a few contests there, and I’d love your vote!

Keep on Making,


Exercise Bike Generator

I’ve always been impressed with exercise bike generator displays at renewable energy exhibits. So, a while back, when I saw a classic Schwinn exercise bike at the thrift store, I nabbed it with the plan to make it into an EXERCISE BIKE GENERATOR!

Earth Week is only a week away, and since our local eco-group is hosting a BIKE-THEMED event this year, I thought I’d “get in gear” and quick put together a bike generator.

I really already had all the parts needed. Mostly, that’s a bike and a permanent-magnet motor. Besides that, it’s just some scrap wood, a bolt, nuts and washers and a bungie-cord.

At the heart of the project is a 12V electric motor. I still had a few parts left over from my electric car conversion project, including the electric radiator fan. My electric car didn’t need an engine or radiator, so I set the fan motor off to the side for future use. I pulled it out for this project. First, I had to remove the plastic fins, which were practically cast in place. I managed to remove them, and get it down to an aluminum hub mounted on the motor shaft.

Next, I cut a scrap of plywood, and used a hole-saw to make a hole in it big enough for the motor to sit in. I put the motor in place, and attached it with three small wood screws.

I drilled a 3/8″ hole through the corner of the plywood, and ran a long bolt through it into the front frame of the cycle. That way, I was able to test alignment of the motor shaft with the front wheel. It matched up pretty well. I would just need to smooth out the hub on the driveshaft and add a stabilizer and tensioner to the motor.

The hub on the driveshaft was bumpy, which made a lot of vibration on the exercise bike tire, and the gear ratio was just a hair off. If I could trim down the diameter of the hub a bit, it would smooth out the ride and allow me to pedal just a tad slower while at the right speed for 12V charging.

I did NOT have a lathe handy, so I thought it would be pretty tough to smooth out the hub. That’s when I realized there was nothing stopping me from JUST SPINNING THE MOTOR. So, I clamped the motor down to a work-table, grabbed the jumper cables from my truck and a 12V battery, and just spun-up the motor! I then used an angle-grinder (with a flapper disc) to smooth down the hub, and reduce its diameter a bit. Because it was spinning at high speed, it came out perfectly concentric and balanced. Not bad for an improvised “poor-man’s lathe”.


I put the motor back onto the cycle and added another piece of plywood opposite of it and a cross-piece to made a basic box shape. This holds the motor solid and lets it swing up and down but NOT side to side.

At that point, all that was left was a tensioner. I added a drywall screw to the wood and attached a bungie-cord from it to the base of the cycle. That applies a light, but steady, force of the motor against the wheel.

I clipped my volt-meter to the two wires coming off the motor and pedaled. Sure enough, it was pretty easy to pedal at a rate that gave me an output voltage between 12-14 volts, what’s needed to charge a 12V battery.

After that, I hooked it up to my Fenix Intl. Ready Set – a 12V battery with built-in charge control and 12V and 5 outputs. It also has a nice charge indicator light on it, and universal power input on the back, meaning I could just run my bare wires straight in and tighten them down without even needing tools. I then only have to pedal fast enough until the “Now Charging” light comes on to know what speed I need to maintain for 12V charging.

This isn’t exactly a fancy or high-power exercise bike set-up, but it sure was easy to build. I did some testing, and it’s simple to output 10 watts of energy. That’s just about perfect for charging an iPad. That also means it’s pretty easy to do something like designing a setup where if you want to watch a movie on the iPad, you have to pedal to make it happen!

Just think how much more fit the average American would be if we all had to pedal to watch TV!

This project took about an afternoon of work and cost me $8, the cost of the cycle at the thrift store. I already had the motor, nuts and bolts, bungie-cord and scraps of wood. All in all a nice little weekend project.

Have you built your own exercise bike generator? What do you power with it? What did you do different on your design? Let us know!

Take care, and keep pedaling!