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Optical detection


Davo
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I have an old organ keyboard I want to midify optically because the buss wires are a mess. What I'd like to do is position an LED and phototransistor pair next to each spring actuator such that the actuator interrupts the beam. Would someone please recommend an LED/phototransistor combination that I can connect to a DIN module with a minimum of support parts?

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Unless the organ keyboard is an especially good one mechanically, it might make more sense to replace it either with a MIDI keyboard or another old organ keyboard in better shape. Old organ consoles often go begging for a home.

This was offered in June. Don't know if it is still available.

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I have an 1960s vintage Artisan Organ, 3 keyboards and full pedals that I would like to donate to someone. I built the organ, starting in 1960 and need to get rid of it. I am about at my wits end because I have contacted churches, etc if anyone would be interested in taking the organ as a donation, and have had absolutely no interest in responses. I have thought about putting it on EBay, but there does not seem to be interest in organs via that mode either. I realize the organ is old technology and that any repairs would be extremely difficult due to scarcity of parts, but thought I would might contact the ATOS in case someone out there might be interested. The shell is in excellent shape, and my thought was/is that it could be gutted of the existing electronics and other equipment night be installed if someone would be so inclined.

As I previously said this would only be a donation, as I just would like for the organ, at least the shell to have another life. At this point my only other option is to take the organ to a landfill and I just despise the thought of that. I have talked with Mr Robert Tall (Robert Tall and Associates Digital Organs, San Dimas, Ca) and he suggested I contact you. I have enclosed several photos that I thought might be of interest.

Thank you for your attention in the matter, and please let me know.

Very sincerely,

Gil Effertz

Frazier Park, Ca

661-245-3504

gdeffertz@att.net

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It's a Pratt-Read keyboard I got off ebay that was formerly found in a Hammond of some sort.

You could look up "photointerrupter" these are a device with an IR LED and matched Phototransistor in a 4pin package. They are mounted in such a way that the mechanical thing you want to do the actuating with passes into a channel in the plastic package/housing where it interrupts the beam. They are low cost (especially with the number you'll be needing). Just run a DC current through the LED's in suitable series stings (or individual current limiting resistors of a DC supply rail) and connect the Phototransistor o/p to DINs. Sounds like a labour of love though, however you do it .

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  • 2 weeks later...

as an example.

may be as here:

http://forum.hauptwe...&t=3777&start=0

and as here:

Line sensing circuit

Filed under: Circuits — Greg Lipscomb ;sensorcircuit.jpg

Here is a simple circuit that can be used to detect a black line in a DIY line following robot. The R1 and R2, need to be picked so that the current or voltage across the LEDs do not go over the specifications of the components. You can use the simple equation V=I*R. V=voltage accross the LED, it could be the 5 volt power source, I is the current through the component, and it can be measured with a multimeter. R is the resistor value. Anyway, the LEDs are infrared, and here are the numbers for them. The infrared Emitter Diode was a Kingbright L53F3C. The Infrared Phototransistor (detector) was a Kingbright L53P3C.

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  • 3 weeks later...

I designed two circuit boards using optical interrupters to replace the contact in Wurlitzer, Rodgers and Gulbransen keyboards. I did this for some Garden State Theatre Organ Society instruments and my own instruments. The circuit boards have eight interrupters each, so a 61-note keyboard requires eight boards, one of which has to be cut down to 5 circuits. One of the circuit boards has the optical slot parallel to the keys and the other is perpendicular. each note has an optional LED indicator to make it easy to adjust the trigger point.

On the Gulbransen, I mounted the boards at the back end of the keyboard and cut thin brass strips to act as flags that block the light path. On the Wurlitzer keyboard, I mounted the boards under the keyboard, using the original Wurlitzer contact bars as the optical flag.

So far they have proved to be highly reliable. The cost is about one dollar in parts for each note plus the cost of the circuit board. The circuit can use anything from 5 volts up to power the optical isolators and LEDs.

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I designed two circuit boards using optical interrupters to replace the contact in Wurlitzer, Rodgers and Gulbransen keyboards. I did this for some Garden State Theatre Organ Society instruments and my own instruments. The circuit boards have eight interrupters each, so a 61-note keyboard requires eight boards, one of which has to be cut down to 5 circuits. One of the circuit boards has the optical slot parallel to the keys and the other is perpendicular. each note has an optional LED indicator to make it easy to adjust the trigger point.

On the Gulbransen, I mounted the boards at the back end of the keyboard and cut thin brass strips to act as flags that block the light path. On the Wurlitzer keyboard, I mounted the boards under the keyboard, using the original Wurlitzer contact bars as the optical flag.

So far they have proved to be highly reliable. The cost is about one dollar in parts for each note plus the cost of the circuit board. The circuit can use anything from 5 volts up to power the optical isolators and LEDs.

A dollar per note is more like it. Where can I find out more information on this scheme?

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