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FrozenGate by Avery

Laser Harp kits - Batch 2 - Finished

Re: Laser Harp kits - NOW PRE-ORDERING!

@ a2dconverter:

Very nice! I just love your case. That is awesome!
I cannot wait to get my kit. (@ Things: "HURRY!! :wave: )

I am thinking of sacrificing an old DVD player as casing.
Then I just need to change the front.

Is the bandpass filter really necessary?
 





Re: Laser Harp kits - NOW PRE-ORDERING!

I ordered the BP Filters from the beginning because I didn't want to be stuck if I needed them! I didn't try it without the filters, and since they are now epoxied to the sensors, now I'm really stuck :-)

EDIT: For the best performance of the LH, I realized that the filters were not necessary. I was able to pry off the filters without damaging the sensors.
 
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Re: Laser Harp kits - NOW PRE-ORDERING!

permanently!!! :yh:
 
Re: Laser Harp kits - NOW PRE-ORDERING!

What difficulties did you encounter?
 
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Re: Laser Harp kits - NOW PRE-ORDERING!

a2dconverter said:
None really, beside learning that I needed to turn Blanking OFF.
Click to expand...

I have had my kit built for a bit now but I have just about been able to play a tune on it with the blanking on which does my 400mW dpss green no favors as the power drops to about 1/10th with the blanking on

My harp dose work a lot better with blanking off like you have discovered but I have a problem with the note on beam 10 also being on about 3/4 of the back stroke line. this means I get two notes if I play beams 3-9. even if I put my finger in between two beams so that just the back stroke line passes my finger you still hear the note set to beam 10. Did you come across any similar issues?
 
Re: Laser Harp kits - NOW PRE-ORDERING!

The dim beam issue is something I've been really trying to look into, but the only thing I can think of is either the lasers aren't handling the speed of the modulation too well, or the code isn't keeping the laser on for long enough for our eyes to realize it's at full power.
 
Re: Laser Harp kits - NOW PRE-ORDERING!

At what frequency are the beams running?

When you look at the video which is in my previous post, you perhaps will notice that the most left beam looks brighter than the other beams.
The beams were created using an (ilda) IShow DAC. You can already see this in my avator which is a screenshot out of that movie.

The human eye can not recognise that a light source is blinking at 25 Hz. You will see a continously burning light.

When you use 10 beams and they are blanking at 100 Hz (each), it means that theoretically the beams should move at 1000Hz which is easily achieved by even a cheap galvonometer and a good ttl blanked laser.

Maybe the scanning of the beams is too fast?
 
Re: Laser Harp kits - NOW PRE-ORDERING!

In a later code revision, I have added an adjustment to allow scan speed changes, however I believe the issue is the last of time between when the laser is turned on, and off again.

For example, if you get an LED, and get it to turn on for 1 microsecond, it'll look dull to your eye, but for that 1 microsecond, it's actually at full brightness, your eyes just don't have enough time to register the light, and it looks dim. I have a feeling the same is happening here. I've come up with a few ideas to try keep the beams on longer without screwing over the timing, but I'm pretty heavily buried under assignments and school work.

This is my 2nd last week of year 12, it's hard enough even finding time to check in here ;)
 
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Re: Laser Harp kits - NOW PRE-ORDERING!

a2dconverter, that is one of the most simple, clean and accurate works I have seen! Nicely explained and a very sexy enclosure. +1
 
Re: Laser Harp kits - NOW PRE-ORDERING!

Things said:
This is my 2nd last week of year 12, it's hard enough even finding time to check in here ;)
Click to expand...


All your time and effort helping each of us with our questions is VERY MUCH APPRECIATED! You've stood behind this all the way.

Good luck with your work and thanks again for putting these kits out.......(i'm still working on mine, but it's close:D)
 
Re: Laser Harp kits - NOW PRE-ORDERING!

Here'a a little demo with my son on the drums and me on the Laser Harp...

The Laser Harp is stunning and much brighter in real life but doesn't translate to Video as well...I had the Camcorder shutter to 1/60th (which is as low as it would go) and 18 dB Gain on the video.

Laser Harp Midi out to a M-audio UNO Midi-to-USB interface triggering a KORG M1 soft synth (Slightly modified "Baroque" patch) on my netbook. The netbook audio out feeds a Carvin Stagemate PA with extension speaker.

If Dan could modify the code, (please!), to allow the beams to stay on a bit longer, then I think that they will be even brighter!

seeya

Joe

YOUTUBE VIDEO:

Laser Harp Composition - "Pierced" by JL - YouTube

New information!

As in the you-tube example, my usual playing style is playing a melody over a drone note. Playing around today, I noticed, as some others in the above posts, that every note that I played as a single note was actually two, the note that I was playing plus the lowest C. (My LH was tuned to the C minor key). I wouldn't of noticed this while playing around as I was holding that Low C as a drone anyway. The other thing that as bothering me was that I didn't seem to be able to play with Blanking ON. I figured that solving the problem of my LH not working with Blanking ON was also the cause of the problem that I was having with two notes sounding with one beam. So, I put on my evil scientist goggles and went hunting...

I switched the LH to Blanking ON. I previously had problems triggering with this mode and nothing had changed until I removed the Bandpass Filters from the sensors. Removing the filters was easier than I thought... I pried them with a small screwdriver and the glass gave to the epoxy.

Now something interesting happened. In Blanking ON Mode, with the filters off of the sensors, when I placed the sensor very close to the harp, as I triggered a specific note beam, that beam became brighter...cool. I thought to myself this is the way it's supposed to work!, But, I couldn't get that to work with all of the beams, the notes were inconsistent and playing two notes at the same time didn't work either... even with the sensor really close to the laser beams. I moved the sensor about 5 feet away and guess what? The beams didn't light brighter when I played each individual beam, but, I could play two notes simultaneously and the triggering was consistent.

So in hindsight, you can play in Blanking ON mode with the sensor about 4 - 5 feet away with consistent triggering and the ability to play chords! Also, even though the sensor is a more likely to be more susceptible to noise from regular lighting with no filters on the sensor, it sure does make everything more reliable. 532nm Bandpass filters not required!

The nice thing is that if I want to play with a low drone, as in my first demo, I can switch to Blanking Off and I can recreate the performance.

Now I have to record another demo! I'm going to try to use an old 8mm analog camcorder that might be more sensitive to the laser light.

Things are the best they've ever been! Looks good for others starting their own builds.
 
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Re: Laser Harp kits - NOW PRE-ORDERING!

The increase in brightness is most likely due to the extra routines the microcontroller has to run when a beam is triggered, like finding and sending the MIDI note, thus taking up more processing time, leaving the beam on longer.

I'll have to look in to keeping each beam on longer, not sure how doable it is without upsetting the timing.
 
Re: Laser Harp kits - NOW PRE-ORDERING!

a2dconvertor, your build skills are amazing!
that video is pretty awesome too :)

Craig
 
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Re: Laser Harp kits - NOW PRE-ORDERING!

Things said:
The increase in brightness is most likely due to the extra routines the microcontroller has to run when a beam is triggered, like finding and sending the MIDI note, thus taking up more processing time, leaving the beam on longer.

I'll have to look in to keeping each beam on longer, not sure how doable it is without upsetting the timing.
Click to expand...

Hi Dan,

The beams lighting brighter was a neat consequence of the sensor being really close to the beams, but it wasn't reliable. THANKS again for doing the homework on the original code looking forward to an update!

Regards

Joe
 
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