Using IR Emitters and Detectors for Dance Pad

[kcowolf]

First of all, I'm a beginner at projects like these, so I apologize for asking any obvious questions.

I have a set of four IR Emitters and Detectors from Radio Shack. I'd like to take apart an Xbox dance pad (**broken link removed**) and wire these to it, but I need some advice on how to do that.

I'm planning to cut off the Xbox plug and solder on a USB plug instead (which I've done before and is straightforward) so I can connect this to a PC, but I'm worried about damaging my USB port or the emitters. The emitter has a maximum voltage of 1.7 V, but I'm not sure how to figure out what resistor I'd need or how to wire it, and I'm not sure if I'll need an external power supply or not.

In short, I'm trying to figure out how to get started with this. If anyone could give me some advice, I'd appreciate it. Thanks.

EDIT: I found these plans for a dance platform using laser diodes, so I'm wondering how much I'd need to change to use the IR diodes instead. Any thoughts?

 

[Mike odom]

the emitter voltage tells you what the LED voltage is when on, and you use this to set the current... (VCC - emmiter voltage) / current desired through LED = Resistor Value... if you use current in mA, R will be in Kohms.

The difference between the LASER and IR diodes is that the laser light will go further without spreading (which causes signal loss) because it is coherent light. We built a Pitch-N-Catch® machine for the Royals one year. It was a box with a 3' x 3' opening placed on home plate that the pitchers would pitch into, and it would display the zone and speed of the pitch (it would also give indication of ball or strike). We used IR and thus had to have lenses on both the emitter and receiver sides. You must lay your parts down and test how far you can detect. I don't remember how far we had spaced each sensor from the other, but we had to detect something the size of a baseball, so it wasn't much larger than the diameter of a baseball. Also, we alternated transmit/recieve pairs for more isolation.

The biggest problem you're going to have, and I don't know how they get away from this in their laser pad unless they multiplex power to the emitters one at a time and now that I think about it that won't work either... anyway, the problem you're going to have is with multiple break points. If you put both feet down, you won't be able to tell which X break goes with which Y break... ex:

Let's say you set up your infrared like the BELOW. ok, one foot goes down, no problem, one broken x and one broken y.... but with two feet placed, you'll have two broken x's and 2 broken y's, and won't know which x goes with which y.... #1 gives the same output as #2

Mike

 

[upand_at_them]

I hope you don't mind me getting in on your thread...seemed a waste to create a new one for a similar question...

I've never used IR before and am making a simple tachometer with this circuit feeding a PIC:
**broken link removed**

For the detector I connected the cathode (short lead) to ground and anode to the resistor/output. Didn't work with anything less than 1Mohm for the resistor. Then I saw a similar circuit that called for the long lead (anode?) to ground. This worked with the 10kohm. So, what gives? It works in reverse?

Mike

 

[Mike odom]

no, you're thinking in reverse... there is no cathode on the detector. The C stands for Collector... the top of the Q1 as pictured in your link.

 

[upand_at_them]

I ordered these a few years ago and didn't have documentation. The short lead is always the Collector?

It does work in reverse, though. With a 1Mohm resistor. Reverse breakdown happening?

 

[Mike odom]

probably more like reverse leakage current (1µA x 1MΩ = 1V).

 

[Mike odom]

The short lead is always the Collector?

it's been my experience the short lead is usually the negative on LEDs and CAPs. On LEDs, this is more standard that the flat. The flat can be anywhere, I've seen them on both sides. On a photo transistor, both leads are N type material, so I don't know what standard they use. The only ones I've used recently have been molded into a single component with a slot between them. I know I have a a few pairs of discrete IR diodes and matchng phototransistors in inventory that I bought years ago, though.

But to answer your question, go to digikey.com and type in photo transistor and look at a couple and see how they're marked, and if they're all the same or some different.

 

[Mike odom]

I'm planning to cut off the Xbox plug and solder on a USB plug instead (which I've done before and is straightforward) so I can connect this to a PC, but I'm worried about damaging my USB port or the emitters.
In short, I'm trying to figure out how to get started with this. If anyone could give me some advice, I'd appreciate it. Thanks.

you realize the USB is a serial port, right? I'm not sure about xbox stuff... never seen it much less tore one apart...

 

[kcowolf]

The XBox connector is the same as USB but with a different plug. There are a lot of guides to connecting a USB plug to an XBox controller. It just involves soldering a few corresponding wires together and installing some drivers.

I see how the breaking multiple beams can be an issue, but I'm not too worried since Dance Dance Revolution uses the up, down, left, and right positions and not the diagonals, so at those positions only one beam should get broken.

I was looking at the guide for the laser dance matrix and it mentioned that laser diodes could be unsafe with bare feet. I'm thinking about adapting this setup for a game called DanceManiaX where you wave your arms over or under the sensors, so I'm a bit concerned about whether a laser diode would be safe for that.

Thanks for the advice. I'll probably try to start this over the weekend.