May I start a laser harp build thread?

[Squonk]

Hi, all. I am embarking on a project to build a laser harp based on Stephen Hobley's plans. I have all the parts (with one hangup being a Scanpro20 set from Lasershowparts that was DOA) and am eager to start. However, as Bones McCoy might say, "Dammit, Jim, I'm a doctor, not an engineer." I have a laser tech's ambitions with a pediatrician's skill set.

So, I'm wondering if I can start a thread here that would accomplish two things:

1. Give everyone else who is trying this a place to share info (Where are you, Jem?)

2. Give me a place to make what I am sure will be many pathetic requests for assistance. (I already have the first one ready to go, but will wait to see if this thread will fly).

Thanks all!

[Laseronics]

Sounds cool, I dont know who Stephen Hobley is nor have I seen his info.

I do know that Tim Walsh with Laser Speticals has made one in the past. http://www.laserspectacles.com/pages/harp.htm

Plenty of other links on Tims site as well... plus the Jarre site. I saw jarre play the laser harp at a concert in Cairo year 2000, It was truly amazing!


Also, we have a new ILDA member that is making them.
http://www.laserharps.com/

[Jem]

Hi Squonk

Of course you may start a laser harp thread. It's very nice of you to ask, but you needn't have bothered. If it's got lasers in it it's good to go

As we've already discussed, I will be very interested in this and following every step, as you know I already have Steve's instructions and a fair few of the parts, my problem is time, money and motivation

We've not heard from Steve (Hobley) for a while on the forum, but i'm sure he's still around somewhere. Hopefully he'll chime in and be able to offer some advice as well. I would like to know how he's going on with the multi colour harp and the Wii remote

May I wish you the best of luck!

Cheers

Jem

[soforene]

Mebbe our own Carl B (the jammiest git alive, not that I'm bitter) will be able to chip in, having built one himself.

[Jem]

Mebbe our own Carl B (the jammiest git alive, not that I'm bitter) will be able to chip in, having built one himself.

Yes, it would be nice for Carl to jump in on this thread and pass on his knowledge. However, the Harp that Squonk and I are talking about is based on Steve Hobleys schematics. This is a *totally* different beast from Carls and I suspect, FAR more complex.

For one, Steve's harp doesn't have any beam termination sensors, and in his latest build you can use a Wii remote to sense the hand position in the beam so that the sound can be modulated by sliding your hand up and down the beam. Also, I believe that he's now built a multi-colour harp so the beam changes from green to whatever colour you like when you stick your hand in it

All good stuff

Cheers

Jem

[Squonk]

OK, so here is my first pathetic request for help. As I said earlier, for an electronics engineer, I make a pretty good pediatrician. I'm hung up on the very first stage of the build and hoping someone here can point out my mistake.

I don't want to infringe on Stephen Hobley's intellectual property, but will post this bit of schematic as I think it is pretty generic. It's the circuit designed to take +/- 15V from the galvo power supply and split out +5 and +/- 6 V

My problem is that, when I measure across the output of the LM7906 regulator and the common, I get only -0.6V instead of the -6V I want. When I measure the same way at the first two regulators, I get the specified output. I can provide more details if necessary, but would really appreciate any pointers.

Thanks!

[ChaosIllumination]

Hi,

Looking at that schematic I see that the LM7906 has pins 1, 2 and 3 listed as Vin, GND and Vout, the same as the LM7806.

This may be wrong. LM79XX regulators usually have pins 1, 2 and 3 as GND, Vin and Vout. It's caught me out a few times in the past!

See this data sheet on page 5 as an example:

http://pdf1.alldatasheet.com/datashe...TC/LM7906.html

Hope that helps.

Regards,
Neil

[Carl B]

Hi Guys

Any thread about Laser Harps then I won't be far away.

My Harp is far more basic than the one that Stephen has built. I would love to move on to the next step and build a frame-less harp if for no other reason than just to make it quicker and simpler to set up.

I have mentioned in another thread that my harp uses light dependent resistors (LDR) as the sensors in a cross frame. When the beam is broken the LDR drops in resistance and triggers a basic Midi controller sending commands to my keyboard.

If there's no objection I'll post some details and photos in this thread on my harp and will be following this thread with great interest.

Just one thing to think about is to use a laser with at least 500mW as getting a sensor to see a beam being reflected of your hand is harder than a beam directly hitting the sensor.

Carl

[Carl B]

Hi,

Looking at that schematic I see that the LM7906 has pins 1, 2 and 3 listed as Vin, GND and Vout, the same as the LM7806.

This may be wrong. LM79XX regulators usually have pins 1, 2 and 3 as GND, Vin and Vout. It's caught me out a few times in the past!

See this data sheet on page 5 as an example:

http://pdf1.alldatasheet.com/datashe...TC/LM7906.html

Hope that helps.

Regards,
Neil

This caught me out once as well and had the reg go pop in front of me. Not a pleasant smell afterwards.

[Jem]

Just one thing to think about is to use a laser with at least 500mW as getting a sensor to see a beam being reflected of your hand is harder than a beam directly hitting the sensor.

Stephen suggests 100mW to 500mW in his instructions. He actually uses a 250mW 532nm laser in his own personal harp. I think the way he has designed it it is particularly sensitive.

Jem