Laser Harp (Open Source) !

[ar1999]

Not sure where you are getting this figure from, unless you are looking at a complete unit .. https://illuminationsupply.com/laser...1d91841c9b14cf

OK, thanks for the link. It sounds good. I couldnt find anything in that price range before...and I probably would have bought one for myself if I had found it earlier.

The only ones I have found before were about US$1200 and up just for the controller. Then I still would have to buy an ILDA Laser Scanner and pay import taxes for both controller and Laser Scanner (100% in my country) so that would be too much for me...

Here are the sellers I found before (I am not afiliated with them in any way):

EUR$799 (aprox. US$1100)
Prolight Laser Harp Controller | Laser Show Projector

US$1,155:
Laser Harp controller for ILDA laser show projectors | eBay

GBP$ 1,110 (aprox. US$1,751):
PROLIGHT LASER HARP CONTROLLER ILDA | eBay

Lots of choices and prices here:
Products | KROMALASER

 

[lasersbee]

What country are you in... There is nothing indicating your
location in your Profile...:thinking:

Jerry

 

[ar1999]

About the laser: currently I am using a 532nm green laser pointer with key, labeled 1W, but since it is from an unknown chinese manufacturer I cant tell if it is a true 1W... But for now it fits the bill.
As I said in another post, I dont have a professional laser measuring device.
Any ideas about other ways to measure it would be highly apreciated.
Anyway, how much current is expected to show at a 1W green laser measurement with a multimeter?

 

[ar1999]

What country are you in... There is nothing indicating your
location in your Profile...:thinking:

Jerry

Brazil (yes, 100% import taxes here!)

 

[lasersbee]

About the laser: currently I am using a 532nm green laser pointer with key, labeled 1W, but since it is from an unknown chinese manufacturer I cant tell if it is a true 1W... But for now it fits the bill.
As I said in another post, I dont have a professional laser measuring device.
Any ideas about other ways to measure it would be highly apreciated.
Anyway, how much current is expected to show at a 1W green laser measurement with a multimeter?

You can only get a very rough idea of power by checking
the battery current draw of your Laser. It is like sticking
a wet finger in the air to check wind speed. You will be
able to feel the direction of the wind and that it is in deed
blowing.

The only real way to know the output power of your Laser
will be with a calibrated LPM...

Going back to your Laser... How much current does it draw
from fully charged batteries. You can check at the Tail Cap...
Put your DMM in series with the Tail Cap connection and place
your DMM to test Amps.


Jerry

 

[ar1999]

You can only get a very rough idea of power by checking
the battery current draw of your Laser. It is like sticking
a wet finger in the air to check wind speed. You will be
able to feel the direction of the wind and that it is in deed
blowing.

The only real way to know the output power of your Laser
will be with a calibrated LPM...

Going back to your Laser... How much current does it draw
from fully charged batteries. You can check at the Tail Cap...
Put your DMM in series with the Tail Cap connection and place
your DMM to test Amps.


Jerry

Using the recommended battery (labeled 3.7v, but with real 4.1 volts Multimeter measured) it draws 480mA.
I also tested it using a 4.5 volt power supply and then it draws 530mA.

I see everybody has at least a couple lasers. Could you share with me these same measurements please?

 

[ar1999]

Since I got no reply here it is again:
I see everybody has at least a couple lasers. Can someone share with me your green lasers current (mA) consumption tests?

 

[Roger O]

Mods, since this is an ongoing open source project, perhaps it should be a sticky?

 

[Ablaze]

My green 5mw (or 12mw without IR filter) draw 275mA. You are going to have a VERY VERY difficult time estimating the power output of your laser based on current draw.

If you really want to know you should get it tested. You can buy a cheap but effective LPM from laserbee, or you can find a local university with a physics department and ask them to test your laser for you.

 

[lasersbee]

Using the recommended battery (labeled 3.7v, but with real 4.1 volts Multimeter measured) it draws 480mA.
I also tested it using a 4.5 volt power supply and then it draws 530mA.

I see everybody has at least a couple lasers. Could you share with me these same measurements please?

I just did a test with my 200mW 532nm Laser with a charged
battery at 4.1Volts. It outputs 281mW and draws 1100mA...

I would suspect your 1W Laser is way underspec...


Jerry

 

[Things]

I'd suggest moving away from using laser pointers for things like this and using lab modules instead. With the duty cycle of a laser harp, it wouldn't surprise me at all if the laser overheated rather quickly. Their drivers also aren't too happy with switching on and off at such speeds, as they need a little time to stabilize each time its turned on.

If you use a lab laser with TTL or analog modulation, there is no need to worry about current draw and transistors etc, it can be controlled directly from the Arduino pin ...

 

[Sputnik77]

Why couldnt you just use one of the diffraction lenses that produce a single row of beams/dots instead of galvos or motors. This would simplify the system as well as make it much cheaper.

I have one and experimented with it and a web cam with Roborealm with promising results. Just need to work out some sort of MIDI "driver" for roborealm.

Here are some pics of the pattern my diffraction grating generates. Dont see why something like this couldnt be used instead of galvos or motors.

 

[Things]

It can be, but like you have said, you need a camera and computer software in order to track the dots. In the laserharp design I use, the beams have to be drawn individually so the sensor knows which ones are being interrupted. That way the uC can draw a beam, check if it's being reflected back. and trigger a note. Because you're doing it one by one, you can trigger as many beams at a time as you like.

The upside to using a camera is you can use things like the position of your hand up and down the beam to adjust things like pitch.

 

[ar1999]

Why couldnt you just use one of the diffraction lenses that produce a single row of beams/dots instead of galvos or motors. This would simplify the system as well as make it much cheaper.

I do have a diffraction lens and I did try this method, but the problem is: it makes the laser light o lot less dim ( it divides it by 10 or 12 or more beams...) so it is not as bright as a stepper motor shining the same laser light.. This is a lot more bright.
Also with the arduino I can program how many beams I want, and I can make a frameless laser harm instead of a framed harp.

 

[ar1999]

Why couldnt you just use one of the diffraction lenses that produce a single row of beams/dots instead of galvos or motors. This would simplify the system as well as make it much cheaper.

Just one more note: I'm not using galvo motors. These are not cheap, but I use a step motor instead (nema17).
You can find nema17 step motors at ebay from US$12.

 

[Sputnik77]

Just one more note: I'm not using galvo motors. These are not cheap, but I use a step motor instead (nema17).
You can find nema17 step motors at ebay from US$12.

I am well aware of all those facts! Also, you are forgetting the cost of the Arduino, and all the other support components. A $12 stepper will not run all by itself!!!!

However, a $5 webcam, free software (especially using Linux), a cheap diffraction grating that when used with fog, is practically just as visible. Yes, it may be a bit dimmer, but still PLENTY visible. Considering most will be using software synths now days, there should be essentially no issue with using a webcam. Also, it has the potential to do a LOT more considering it is PC/Image based, instead of an Arduino!!!