Infrared air hockey game scorer help needed.

[Boonie]

I have acquired an air hockey table that is missing a componant that triggers when a score is made. One side is complete and I believe it to be designed by a small inferred sensor on each of two sides, that triggers a score when the puck breaks the beam. The exisisting sensors on that side are about the size of a pencil eraser and are connected to a phone wire that runs to the scoreboard. I would like to figure out where one can get such sensors and what the differences might be in them. The scoreboard does not give any brand or numbers. The exisisting scorer runs directly to the circuit board of the scoreboard. Any guidance on how to modify something on the missing end would be appreciated by by kids! Thanks!

 

[(*steve*)]

Is there just one sensor (that is missing) or are there several and one is missing?

It may be tricky to determine what sensor is used without something to compare it to.

Alternatively, if you can give us a make and model number (or if you have a service manual or a schematic) we would be better placed to figure it out.

The last option would be a photo of the circuit board that the sensor is connected to. This may give hints as to the type of sensor.

The sensor is likely to be either a CdS cell or a phototransistor if the detection is optical. Presumably there is also a light source opposite the sensor?

 

[Boonie]

Steve - thanks for the reply.

I have tried researching the mfg and had no luck. It is stamped Easton and I believe made by Playcraft. They have not responded to my request for info.

I attached a photo of the puck chute. The two sensors sit across from each other and the right one I took loose. It appears that the "sensor" is the size of an LED, and sits inside the small plastic piece that I took loose. Not sure I can take the actual "sensors" out of that plastic piece to see if they have any numbers or markings on them, but will look at that now. I am missing both these "sensors" on the one end of the table. Not sure this helps or not. I can take a photo of the board if that would provide any direction.......thanks again.

 

[Boonie]

Here is a pic of the two "sensors." One appears to be a light blue color and the other is a rather dark blue. No markings on them that I can see.

 

[(*steve*)]

Certainly looks like an infra-red LED and phototransistor.

 

[Resqueline]

What Steve said. They look like 3mm parts. You should be able to replace them with just about any reasonably matched pair (of any diameter - if you can fit'em).
The ligher will be the LED (emitter) and the darker will be the phototransistor (detector). The flat spot on their side denotes their polarity.

Radio Shack has a high output infrared 5mm LED (940nm) # 276-143 for $2.19
They have a separate Infrared 5mm Phototransistor # 276-145 for $1.99 (unknown spec's).

Or you can get the 5mm Infrared LED Emitter and Detector pair # 276-142 for $3.69
Emitter: Radiant power output: 13-15mW, Wavelength (peak emission): 950nm
Detector: Peak sensitivity wavelength: 850nm Spectral bandwidth range: 620-980nm

 

[Boonie]

Thanks guys.......I'll run with that and see what I can do........

 

[Raven Luni]

You should be able to replace this with pretty much any light and sensor pair if you know the triggering voltage required. You can get a good idea of this by taking readings from the working side. Then again, aiming for as large a difference as possible should also work if its a simple logic level circuit - so a phototransistor or even an LDR connected to a comparitor would ensure success. You could even replace the LEDs with small laser modules if youre feeling adventurous.

 

[Boonie]

I am a novice in electronics soooooooo...what is the best way to measure the voltage? I have a digital meter. In my photo, the LED has a green negative lead and a yellow positive lead. The darker one (detector) has a black negative lead and a red positive lead. If it is all hooked up and running, at what points would I check (assuming on the circuit board where these leads connect)? Or would it likely be safe to use the parts that Resqueline mentions................The transformer for the main unit is a 6VDC. Thanks again.

 

[(*steve*)]

Follow Resqueline's advice. It's what I'd do.

 

[Resqueline]

It's a no-brainer, just get an infrared pair and copy the connections from the working side, noting the flat spot on their "collar" and getting emitter & detector righ.
If you measure across yellow/green you'll get 1.2V with the LED present and approx. 6V without the LED there.
Measuring across the red/black you should get approx. 6V with no transistor present, and also if it's there but kept dark. If lighted it should fall below 1V or so.

 

[Boonie]

Need some help troubleshooting. Assembled the emitter/detector with the same configuration as the working side. Had no luck in getting it to trigger a break between the two. I confirmed that the connections are all solid and the device works were plugged in. The problem seems to be in the emitter/collector end of things. I am not sure if it would have to do with the particular parts I used (the Radio Shack pair 276-142) or something else. From what I read on the parts (reviews) I obtained, they have the package labled wrong regarding which is the detector and emitter. I used the tinted one as the detector and the clear as the emitter (same configuration as the existing unit). If checking to see that the emitter is good, at what points would I check? Is there a way to check to see if the detector is working? Thanks!!

 

[Resqueline]

You can check the emitter by measuring the voltage across it, as mentioned above. Around 1.1-1.2V means it gets a drive current - and should light.
If it has 6V across it then it may have been packaged incorrectly and you'll need to try it the other way around.
You can check the actual light output by looking at it through any digital camera.

The detector can also be checked by measuring the voltage across it, as mentioned above. You can put a remote control in front of it and see if it responds to that.

Not having seen the packaging print I can't say anything whether the information given there is incorrect or not.

 

[OLIVE2222]

Hi, according to the following link it's the opposite, the tinted one is the emitter and the clear one is the detector.
http://www.pages.drexel.edu/~pyc23/ir_sensor.html

Olivier

 

[Boonie]

Checking to see if I have the correct parts with the measurements that I have. I obtained the following measurements and they appeared the same at the device source and across the leads of the emitter/detector:
yellow/green 4.41v
red/black .666v

the specs on the package of the parts are:
detector (clear)
Collector to emitter: 70V
Emitter to Collector: 5V
Collector Current: 50mA
Total Power dissipation: 150mW
Peak wavelength: 850nm
Bandwidth range: 620-980nm
emitter (tinted)
Reverse Voltage: 5V
Continous forward current: 1.3V typ 1.7V max
Radiant power output: 13-15mW
Wavelength Peak 950nm

It is not working with this configuration.Unsure if the wrong part or defective part. Looks like the measurements are near what has been recommended them to be - thoughts? Thanks for the previous feedback......

 

[Resqueline]

It would be strange if the detector is clear since it needs an optic filter in order to not be sensitive to visible light (but the world has seen stranger things).
IR LED's are often tinted but don't actually need to be since the chip only emits one wavelenght. It is rather easy to test these parts though.
The yellow/green (where the LED is supposed to be) has too much voltage for it to be a LED on there now, and the red/black part seems to conduct too much.
Suggestions:
Measure the voltages on the working side, noting light sensitivity and polarity also.
Check the Radio Shack parts with the diode test range on your DMM (if you have).
Try swapping the two components around if the above doesn't tell you what is what.

 

[(*steve*)]

Or with a small amount of current going through it, look at the device through a video camera. They're often sensitive to IR and you may see the emitter glowing. You can test your camera with a TV remote control, you should see it flashing if your camera is IR sensitive. It may even work on a cellphone, although I've not tried.

 

[OLIVE2222]

Hi, I confirm that the world has seen stranger things

http://www.radioshack.com/product/index.jsp?productId=2049724
http://www.radioshack.com/product/index.jsp?productId=2062565
http://ecatshow.com/z.htm

Olivier

 

[Boonie]

ok - I reversed the emitter/collector and it appears to be working. Weird that the existing side had a clear clear and I used the tinted one (as the package reflected). That being said, I need to increase the sensitivity some. It appears to have a range of about 2-3 inches and I need about 4-5 to span the gap where the puck goes through. Not sure what to tweak to get this to work better. My readings are as follows:
Existing side:
across the emitter: 1.22 V
across the collector: .66 V

New Side
across the emitter: 1.42 V
across the collector: .65 V

On the new side, I do not have the emitter/collector in a small black piece of plastic (tube shape that appears to direct the beam) as the existing side had. I am guessing that this has something to do with it's performace. I will see if I can rig something to do the same. Other suggestions to get a little better range?

Thanks you guys for your help.......

 

[OLIVE2222]

Hi, you can try to fit a plastic tube first, then you can increase the led current by decresing is serially connected resistor.
Olivier