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Hey all. Thought I'd take the time to post a bit about my latest project.
First I'd like to say that I was only able to do this with the help of other peoples hard work from around the internet,
and other than the actual build I came up with nothing new here. I used chunks of info from this site,
Instructables, Hackaday, Youtube, and tons of other non-laser related sites.
This project is not finished, I'm still waiting on parts for the laser that I will be using in the end product.
The following pics are using a 50 mw green pointer.
The following items are needed for this project:
1: Laser Safety Goggles. Don't even think of attempting this project without them.
2: A cheap galvo set. I got mine on Ebay for $89. They are the 20k set with show card.
The show card can be sacrificed for parts, which is handy. You will only need the power supply, one of the galvo driver boards and one galvo.
3: A Teensy 3.1. This is an Arduino compatible MC with a built-in 12 bit DAC.
It's cheaper to buy a Teensy than it is to buy an Arduino and a stand-alone DAC, plus it makes programming much easier.
Sparkfun and Adafruit both carry these at around $20.
Be sure and download the Teensy add on library for the Arduino IDE
4: A TTL controllable laser. It needs to be of high enough power to be divided into at least eight beams
and still be visible with some smoke. A 50 mw green is the bare minimum.
I went with a blue 2000 mw because I like blue lasers and they are much cheaper than green for the same power output.
5: A differential amp. This part you will have to build. I know of no source to buy these.
I built mine on perfboard, but you can use a small prototyping board or roll your own board.
6: Various components for the midi section of the harp. Here is the schematic.
7: Various components for the photo detection circuit. Here is the schematic.
8: A case to mount everything in.
9: A smoke machine. Party City carries a cheap one that will get the job done for about $30 bucks.
10: Midi to USB adapter. Ebay has these for less than $10
So all in all, I built this harp for about $200. I got a great deal on my laser, which really helped with the price.
Like I said, I got all my info from other people,
and just put this thing together like a puzzle.
I found a neat harp on Instructables Frameless Laser Harp and modified his code to work with the Teensy 3.1 If you wish to build one without using galvos, this is the way to go.
For the differential amp, I used the schematic posted by Benm and it can be found on page 3 of the Sound Card Dac tutorial, post number 45. All the components needed are available at your local Radioshack. I built mine on a 2x2 inch piece of prefboard. This connects to pin A14 of the Teensy, which is the DAC output.
Once the amp is built, follow Benm's guide to calibrate it, using this Arduino sketch.
Calibration Sketch
Once calibrated, connect the amp to the power supply, the galvo driver and test again. The galvo should rock back and forth slowly.
Next modify the Calibration sketch by cutting the delay down to 3 or 4 ms. The galvo should speed up considerably. With no delay, the galvo will just hum. The output from the Teensy is way too fast for the galvo to follow.
Next, build the photo sensor circuit. You can use any pin on the Teensy that is analog in. This is only two components and you need to use a variable resistor instead of the one shown in the schematic. I used one of the pots that came with the galvo set because it was what I had. This will allow you to tune the circuit for ambient light. Use a full size pot and knob and mount to be accessible with the case closed. The photo resistor has to be mounted on the outside of the case to see the reflection of the laser. I cut the leads short on mine, soldered two long wires to it and and then ran it to the Teensy.
Next, build the Midi circuit. This requires one 220 ohm resistor and a midi jack. I got the jack from Sparkfun. Once that's done, load the Harp software
Harp Sketch
to the Teensy, connect to your favorite Midi software and away you go.
You will need to modify the code depending on which pins you use for the Teensy for the analog input. The output to the differential amp has to be on pin A14. The delays at the top of the file will have to be modified depending on your galvos. Super easy to do.
If you have any questions, let me know. As soon as the rest of the parts come in, I will post some videos.
First I'd like to say that I was only able to do this with the help of other peoples hard work from around the internet,
and other than the actual build I came up with nothing new here. I used chunks of info from this site,
Instructables, Hackaday, Youtube, and tons of other non-laser related sites.
This project is not finished, I'm still waiting on parts for the laser that I will be using in the end product.
The following pics are using a 50 mw green pointer.
The following items are needed for this project:
1: Laser Safety Goggles. Don't even think of attempting this project without them.
2: A cheap galvo set. I got mine on Ebay for $89. They are the 20k set with show card.
The show card can be sacrificed for parts, which is handy. You will only need the power supply, one of the galvo driver boards and one galvo.
3: A Teensy 3.1. This is an Arduino compatible MC with a built-in 12 bit DAC.
It's cheaper to buy a Teensy than it is to buy an Arduino and a stand-alone DAC, plus it makes programming much easier.
Sparkfun and Adafruit both carry these at around $20.
Be sure and download the Teensy add on library for the Arduino IDE
4: A TTL controllable laser. It needs to be of high enough power to be divided into at least eight beams
and still be visible with some smoke. A 50 mw green is the bare minimum.
I went with a blue 2000 mw because I like blue lasers and they are much cheaper than green for the same power output.
5: A differential amp. This part you will have to build. I know of no source to buy these.
I built mine on perfboard, but you can use a small prototyping board or roll your own board.
6: Various components for the midi section of the harp. Here is the schematic.
7: Various components for the photo detection circuit. Here is the schematic.
8: A case to mount everything in.
9: A smoke machine. Party City carries a cheap one that will get the job done for about $30 bucks.
10: Midi to USB adapter. Ebay has these for less than $10
So all in all, I built this harp for about $200. I got a great deal on my laser, which really helped with the price.
Like I said, I got all my info from other people,
and just put this thing together like a puzzle.
I found a neat harp on Instructables Frameless Laser Harp and modified his code to work with the Teensy 3.1 If you wish to build one without using galvos, this is the way to go.
For the differential amp, I used the schematic posted by Benm and it can be found on page 3 of the Sound Card Dac tutorial, post number 45. All the components needed are available at your local Radioshack. I built mine on a 2x2 inch piece of prefboard. This connects to pin A14 of the Teensy, which is the DAC output.
Once the amp is built, follow Benm's guide to calibrate it, using this Arduino sketch.
Calibration Sketch
Once calibrated, connect the amp to the power supply, the galvo driver and test again. The galvo should rock back and forth slowly.
Next modify the Calibration sketch by cutting the delay down to 3 or 4 ms. The galvo should speed up considerably. With no delay, the galvo will just hum. The output from the Teensy is way too fast for the galvo to follow.
Next, build the photo sensor circuit. You can use any pin on the Teensy that is analog in. This is only two components and you need to use a variable resistor instead of the one shown in the schematic. I used one of the pots that came with the galvo set because it was what I had. This will allow you to tune the circuit for ambient light. Use a full size pot and knob and mount to be accessible with the case closed. The photo resistor has to be mounted on the outside of the case to see the reflection of the laser. I cut the leads short on mine, soldered two long wires to it and and then ran it to the Teensy.
Next, build the Midi circuit. This requires one 220 ohm resistor and a midi jack. I got the jack from Sparkfun. Once that's done, load the Harp software
Harp Sketch
to the Teensy, connect to your favorite Midi software and away you go.
You will need to modify the code depending on which pins you use for the Teensy for the analog input. The output to the differential amp has to be on pin A14. The delays at the top of the file will have to be modified depending on your galvos. Super easy to do.
If you have any questions, let me know. As soon as the rest of the parts come in, I will post some videos.
