my arduino-projects: laser harp, thermoscan, 3d-scan, segway


Here are some pictures of my recent arduino projects.

First my simple laser harp using a 20mW DPPS-laser, a LDR, stepper and MIDI-output for the right sound

Second my cheap thermocam, using a Melexis 90614-DCI with 5°-resolution

Third my 3D-ultrasonic-scanner, based on the same servo-plattform like the thermocam.

And fourth my DIY-segway using a sabertooth 2x60 motor-controller, two 24V/250 motors, two sensors (gyro + accelerometer) and a kalman-filtering. At the moment I had (have) some problems sending the motor-values to the controller. But now it seems to be solved and I’m waiting for my first working ride. The first version using two fullbridges and PWM wasn’t powerfull and sensitive enough and therefore I decided to buy a commercial product.

wow!! Wonderful projects!! I'm just starting a similar harp project too..

But I'm going to planning to use a sharp GP2Y0A02YK0F proximity sensor (which has 1,5 meter of range) for each laser beam and no galvanometer.. The angle of the prox sensor is 5°, so I have about 10 cm of space at 1meter as switching space.. I could use 7 lasers pointers used just as guide for my hand.. but the true job would be done by the prox sensor (rec+trasmitter)

I think that it would be no such expensive.. for 7 notes, I need 7 sensor (about 13$ each) and 7 cheap laser pointers..

But I still need to study a bit for this solution.. did you thought to this solution?

Can you give me some ideas? thanks Paolo

Hello Paolo!
My first attempt of a laserharp used many laserpointers too. I took the electric piano of my children ( :cold_sweat:) and connected the notes to the phototransistor-circuits.
The above pictured version using the stepper isn’t very complicated. But the speed is very limited (stepper and no galvos) and the light detection with the LDR not very sensitive. The more sophisticated versions seen in the internet work significantly better, but they cost much more and are more complicated to build.
Concerning your version I would just have doubts that the angle of each sensor isn’t small enough and so that what sensor interacts with his neighbours. When you need 7 proximity sensors than your version will be more expensive than my one.
I wish you good luck with your project! :wink:

Thanks fot your fast reply,

yes, I have your same doubt about the prox sensors angle, but.. I will take it as an experiment.. I can start with a couple of sensors, and look if there are interactions between them and valutate if it is reasonable to build..

7 sensors will cost about 90€ 7 laser pointers will be about 3-4€ each one.. an arduino.. and few other components..

I think I can contain the cost under 150€. Another doubt come into my head.. the response time of the prox sensors.. As they come with an integrated circuit, if they would need more than 10-11 ms to eaborate and send me the information.. It will be too much time.. So I'll need to follow another way..

I'd like galvanometer solution, but I think It will be more expensive, compared to mine.. I've seen prices of galvanometers starting at 90-100€, and I need then to build a controller..

I still need more documentation, but.. I wanna start with a couple of prox sensors as mentioned.. I can always recycle them to other projects if they won't work..



I don't think that the response time is too long. The sensors just send you the information, when your hand is within a specific range. Therefore I don't think that it's important, whether the hand-signal and the output of that note delays for some milliseconds.

On ebay you can find cheap galvos for 80 Euro. The drivers for the x- and y-galvo need +/-10V analog signals. So you just have do generate a sawtooth-circuit for one galvo. ;)

Here are some of my other projects. Maybe they are a little inspiration for anybody...