laser Harp V2 open and free

[Carl B]

At that price I am all for YOU soldering! I think an option with a case or without would be fine... I do have another idea to make a laser harp more simple involving Ronchi Rulings or a grating rather than scanning a beam. That is another project, with the Arduino code and sensors, no complaints at all on the design at all. I thought I would get the idea I have had for awhile out in the open.

-Adam

-Adam

Hi people.

The first harp that i built used a grating and I found that the power of the laser was not equally spread across the fan of beams after the grating and the overall power loss was a lot as well. Plus how would you get a single sensor to work out which beam you have broken? The harp I built had a Light dependent resistor for each beam in a overhead cross bar.

For me the V1 harp would be perfect for my needs as it looks to be just like the one that Jarre is using on his stage.
Dose the V1 harp open and close?
How do you asign a Key / Note to each of the beams and is it easy / quick to change the note to beam asignment?

Carl

[Genesis]

the V1 one use obsolete parts now and the best way is to use the new one.
to assign a note like in the videos you needs to play a note to the harp and play the note to a master kayboard like synthetiser or midi software keyboard.
the harp microcontroller receive the midi note and store the value in eeprom

the V1 is only a open frame.


for the V2 closed frame mode i think to use an acrylic tube used in "light pipe" mode with a single ptotodiode at the end. the beams are received along the tube and collected by the photodiode
in this mode the harp is surely less sensitive to ambiant light.

[300EVIL]

hi all
don't worry about the box because i've made the routing using a box from Hammond Manufacturing available at radiospares.

Ah, I figured that was the "case" with the way you had the board notched out. Any chance you can post the parts list so I can work out cost?

for the V2 closed frame mode i think to use an acrylic tube used in "light pipe" mode with a single ptotodiode at the end. the beams are received along the tube and collected by the photodiode
in this mode the harp is surely less sensitive to ambiant light.

Cool! So only one PD. I'm guessing each beam is modulated so the harp board knows which beam is blocked. Very nice!

[Carl B]

for the V2 closed frame mode i think to use an acrylic tube used in "light pipe" mode with a single ptotodiode at the end. the beams are received along the tube and collected by the photodiode
in this mode the harp is surely less sensitive to ambiant light.

I think you miss understood what I ment. I was meaning do the beams open and close like a fan from a single beam?

Carl

[Genesis]

sorry i don't understand what you say.
perhaps you are talking about the opening and closing the harp from one beam?

[Carl B]

Yes that's exactly what I mean just like how Jarre's harp dose. Sorry for not making my self clear about what I ment.

Carl

[Genesis]

Hi all
some news about the boards:
just 3D models from Eagle3D and PovRay

the sensor one with OPT101 photodiode


and the mainboard in 3d:

[mccarrot]

Wow very nice job

But I see the whole pcb is smd. smd is difficult to solder for DIY. are you willing to deliver complete assembled pcb's?


Keep up the great work

[300EVIL]

Any details on pricing of the bare PCB's?

[Genesis]

Wow very nice job

But I see the whole pcb is smd. smd is difficult to solder for DIY. are you willing to deliver complete assembled pcb's?


Keep up the great work

i know but the V2 was made from standard components but theses one are no longer available in DIP (like D/A converter)
no idea of the price because i need to make samples before.

[FourDee]

I know smd seems harder than thought hole, but once you get started with smd, you will never want to go back.

[T0mmm]

I'd also be interested in a PCB and a box/list of components that i'd need

This project sounds awesome; i'd love to assemble my own one

[Stoney3K]

Cool! So only one PD. I'm guessing each beam is modulated so the harp board knows which beam is blocked. Very nice!

Let a fellow harp-builder enlighten that for you...

The harp is nothing but a one-axis scanning projector (any projector will work, as long as the Y galvo stays put) with the aperture pointing upward.

Detection works through a single photodiode because the PD signal's timing, not its intensity, is important for determining the beam which was struck. After all, a specific timing on the PD corresponds with the galvo position at the moment the reflected beam was received.

The whole thing actually is pretty similar to the electronics inside your keyboard. Instead of a chip having 104 input pins and switches for each key, the encoder does a rapid row-by-row scan of of the key matrix, and by examining the timing on the input pins, it 'knows' which keys were pressed or released.

If the harp was projecting all beams simultaneously, it would be a lot more difficult to make it a frameless harp (with beams going up into the air forever), since it requires a photodiode for each beam targeted exactly at the player's hand. The scanning design is a lot more compact, efficient and allows the PD intensity to be used for a modulation or expression controller.

@mccarrot: I am developing a harp with through-hole components only and an ATMEGA8 as the master brains, and DAC's based on the Microchip MCP4921 SPI 12-bit DAC chip. For the detection, I am using three photodiodes spread over a little wider area (like Jarre's detection system in the World Arena Tour) and a fourth PD which is used for compensation of ambient light.

The detector has a differential output, which means that any detector signal which has both outputs at logic high or outputs at logic low, means the detector is either not connected or at fault. The controller picks that up, and shuts all the interlocks for safety purposes.

[Genesis]

my friend actually work on the website.

http://www.harpelaser.com

but this is just the beginning

[mccarrot]

Any updates on this nice project

[300EVIL]

Yeah, I really want to build one. Any news on price of the boards? Parts list?

[Genesis]

i'm waiting to have one working prototype before to create the part list and other.
the boards are in manufacturing step and normally shipped the 10 march.

[Genesis]

Hi all
i've received the boards!
very good quality with HASL finish.
now i need to solder the components ^ ^

[Stoney3K]

Boards look great! You don't mind sending me one for a sample, so I can compare the performance with my own unit?

Too bad Manuel Schulz decided to close down the Laser Harp Pages. There was some useful info on there, and the discussion boards were barely getting off the ground.

[mccarrot]

Where can I place the order?

[Genesis]

lol!
just wait to know if that work
i've discussed with utopia and i think the best way is to sell the entire board with components on it because this is the easiest way for anybody to build one. perhaps keep the possibility to have only the boards without components but the smd components are expensive.
A board manufacturer use large quantities of resistors with a really low cost!
i need to build one functionnal unit before to calculate the price...

PS: i've seen Jean Michel Jarre in concert that was great but some music was played in plyback on the laser harp i think...

[Stoney3K]

lol!
just wait to know if that work
i've discussed with utopia and i think the best way is to sell the entire board with components on it because this is the easiest way for anybody to build one. perhaps keep the possibility to have only the boards without components but the smd components are expensive.
A board manufacturer use large quantities of resistors with a really low cost!
i need to build one functionnal unit before to calculate the price...

It might even be more cost-effective to look into selling complete units. Just a box on the floor, turn the key, hit the foot pedal, plug and play. I guess even a big instrument manufacturer like Moog, Roland or Yamaha may be interested in getting the thing mass produced.

PS: i've seen Jean Michel Jarre in concert that was great but some music was played in plyback on the laser harp i think...

Jarre does mime the harp on several major concerts (including Beijing and Houston), just to make sure that the whole concert, with millions of people watching at the same time, isn't going to be ruined by equipment failure. His detection system is quite prone to fault, causing the whole unit to crash and go quiet.

On most tours, such as the World Arena Tour last year, he's definitely running the thing live. I was about 50 feet away when he screwed up in Amsterdam.

[Genesis]

yes that can be understood

some news of the project!
i've worked all the week end on the harp (and more important thing > the coffee )
some pictures:
me with the solder paste:


soldering a component:


first step (passive components):


second step (active components)


last step (connectors and transformer):


and the crucial moment! the first test!

no smoke! and all things seems to be good

after some mechanical adjustments


the front panel PCB:


the mainboard:


and few C lines after:




there is some mistakes on the pcb like switch clearance, mechanical assembly issue and some signal routing error but this is not so bad for a V1 prototype
now this prototype is ready for my friend who work on the code

i keep you in touch

[mccarrot]

Looking good!!!

[Genesis]

yes
all is fine actually.
the analogue circuitry work well and the DAC too