What's your input to this Sensor Project?
th1961
Posts: 6
Hello everyone,
I am trying to introduce electronics to my two sons (& myself) by building a fun project with them. You guys have some great projects that you are dicussing and I heard this is the Best place to start, so we are hoping you can give us some direction. I did come across this web page on infrared train detection·( http://www.mrollins.com/irled.html ). The gentleman contacted me and said that his solution will Not work because the IR is not sensitive enough. I've never done this type of thing before, I'm not an engineer,··I do have some technical skills. I am a web developer and I did programming in RPG II for the IBM AS/400 for about 10 years; so it's a learning experience for me as well.·
Are you familiar with table hockey? Here is a link to what the game looks like:
http://zebtech.com/th/photelectric-sensor-diagram.jpg
Here is an overview of what we want to do:
THE ISSUE:
When playing table hockey, sometimes the little 1 inch diameter puck goes into the net and bounces out so fast that sometimes we are not sure if the puck went into the net or not.· The red goal you see in the picture is about 3 inches high by 4 inches wide.
THE SOLUTION:
When the little black puck fully crosses the red goal line and goes into the goal net, we would like to turn on a red light for 4 seconds indicating that a goal was scored. I don't think this can be acheived with one sensor, but a series of sensors that create a "curtain" across the entire opening of the goal. When just one of these sensors are tripped I want to turn on the red light. *A special note, the puck cannot be modified in any way.*
Here are some "Mock-Up photos" of how it might work:
http://zebtech.com/th/mock-up1a.jpg
http://zebtech.com/th/mock-up2a.jpg
I'm thinking we can achieve this by using infrared beams or photoelectric sensors. We've searched on the Internet and have come up with nothing. Of couse I'm not sure what I'm looking for.· Can you please help us.
Thank you in advance for your time.
Sincerely,
Dad
I am trying to introduce electronics to my two sons (& myself) by building a fun project with them. You guys have some great projects that you are dicussing and I heard this is the Best place to start, so we are hoping you can give us some direction. I did come across this web page on infrared train detection·( http://www.mrollins.com/irled.html ). The gentleman contacted me and said that his solution will Not work because the IR is not sensitive enough. I've never done this type of thing before, I'm not an engineer,··I do have some technical skills. I am a web developer and I did programming in RPG II for the IBM AS/400 for about 10 years; so it's a learning experience for me as well.·
Are you familiar with table hockey? Here is a link to what the game looks like:
http://zebtech.com/th/photelectric-sensor-diagram.jpg
Here is an overview of what we want to do:
THE ISSUE:
When playing table hockey, sometimes the little 1 inch diameter puck goes into the net and bounces out so fast that sometimes we are not sure if the puck went into the net or not.· The red goal you see in the picture is about 3 inches high by 4 inches wide.
THE SOLUTION:
When the little black puck fully crosses the red goal line and goes into the goal net, we would like to turn on a red light for 4 seconds indicating that a goal was scored. I don't think this can be acheived with one sensor, but a series of sensors that create a "curtain" across the entire opening of the goal. When just one of these sensors are tripped I want to turn on the red light. *A special note, the puck cannot be modified in any way.*
Here are some "Mock-Up photos" of how it might work:
http://zebtech.com/th/mock-up1a.jpg
http://zebtech.com/th/mock-up2a.jpg
I'm thinking we can achieve this by using infrared beams or photoelectric sensors. We've searched on the Internet and have come up with nothing. Of couse I'm not sure what I'm looking for.· Can you please help us.
Thank you in advance for your time.
Sincerely,
Dad
Comments
Of course, if you decide to go the microcontroller route, I'd suggest the SX28 from Parallax. You could use PORTB interrupts to monitor the detection and display the appropriate light; heck, you could even have the SX keep track of the score.
Post Edited (JonnyMac) : 1/25/2007 8:52:35 PM GMT
Power
IRSENSORs
HEXFET
Restor/capacitor---gate of Mosfet
LIGHT
Cant draw a schematic now but if you need one I can do it later tonight.
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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!
Thank you so much for the help.·This is GREAT! ·I did buy·the Radio Shack Electronic Sensor Lab Kit a month ago·from someone and it does have the "Electronic Sensor Lab Workbook" by Forest Mims III (Copyright 2001).
Metron9 you are correct, because the puck can be lifted in the upper left and right corners, there has to be what I call a "full curtain" of sensor area, from top to bottom, side to side. I would really apppreciate it if you can draw a schematic. Thank you in advance for your time.
·
Do you want to use a battery pack say 3 AA batteries for power and then just 2 LED's at 20ma or less for the on goal lights. Post a list of components you have perhaps just a PNP transistor could be used instead of the hex inverter.
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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!
Post Edited (metron9) : 1/26/2007 4:14:14 PM GMT
This is what came in the Radio Shack Sensor kit (as far as the detailed specs of each unit, I would have to look at it,·I don't have it with me where I am right now.)
- Console
- Removable Sensors (6)
- Sensor Interfaces (5)
- Integrated Circuits (34)
- Resistors (17)
- Capacitors (10)
- Light-Emitting Diodes (3)
- Transistors (2)
- Miscellaneous Items (Springs/Clips/Wire Segments)(74)
- Owner's Manual
My guess is that I will probably have to buy all the parts.· I·don't have a hex inverter; Radio Shacks web site does't list one either.You recommendation of 3 AA batteries for Power sounds good.·It the future an AC adapter would be a nice option, but I'm not going to worry about that just yet.· I need to crawl before I can walk. :-)
I look forward to hearing from you.
-TH1961
Post Edited (th1961) : 1/26/2007 7:36:34 PM GMT
I just got my digikey shipment today with hundreds (yes I do go overboard sometimes) of photo transistors. I will of course be experimenting with them so I may just be able to mail you finished units or breadboarded ones. I have tons of hex inverters waiting for the chance to be used.
The lowest cost photo transistors are 12 cents each so the arrays of 6 on each side wont be much. Can we have drilled holes with them in the bottom perhaps we could even use epoxy to fill them in and sand it and polish it down to make a nice insert. I have 3mm size so the holes wont be very big, may need to put some led's on the inside lip on the top of the net to have this work in any light conditions though. Could use infared or UV if you dont want to see the light. Actually a thin piece of acrylic bent around the front of the net an sanded could be used as a light pipe to light the photo transistors and serve as the goal light, maby even blink it a few times on scoring hmmm I smell a 555 timer in this now, hmmm maby just use a tiny13 .. or, .... hmmmm...thinking... thinking..thinking...
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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!
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Problems are the "roads" of life,
solutions are only "onramps" to the next problem
············································· "Brad Smith"
·
Thank you for the suggestion.·If I understand you correctly, I'm not sure if the switch will work?? Can you elaborate please?
Thank you again.
I have 5 sensors in series (you will want a few more to go across the full net) I soldered them to a board put foam around them and stuck a piece of clear lexan with a 1/4 inch clear space blocking the rest out with black tape. I would have used black epoxy to encapsulate themand just leave the little bump that receives the light vi sable but I misplaced my epoxy, it's around here somewhere.
5V into one side of the sensors to a 1k resistor the other side of the resistor to a 10k pot the other side of the pot to ground
This makes a voltage divider. Where the resistor and pot connect i measure that point with an ADC on a tiny13
I left shift to drop off the low bits and get a number from 0 to 255
To tune the system you turn the pot until the LED turns off. Then back up till it goes on and a bit more, this sets the sensitivity.
The adc measures the voltage compared to the VCC
I have one variable initialized at 127
I compare the adc value with the variable
If it is lower than the variable I make pin5 LOW and change the variable to 255 go back to loop
If its higher than the variable I make pin5 HIGH and reset the variable to 127
This allows hysteresis of 127 turning off and back to on so a value near 127 won't false trigger from noise.
PIN6 will go high for 4 seconds when the sensor is triggered
PIN7 will toggle for 4 seconds at 4 HZ in case you want to put in a beeper or something
PIN4 will go from high to low from a high for 4 seconds then back to high in case you want a low signal instead of a high signal.
PIN3 is the ADC
PIN4 ground and PIN 8 VCC +5V
I have tested it using a pencil putting pressure on the pencil and snapping it across the sensor as fast as I can like you might fire a spitball across the room.
The scope shows a 1mS drop, that is the shadow that the pencil makes as it goes across the sensor.
Some math:
The pencil is traveling across the sensor with a shadow size of about 1/4 inch
we take 1/4 inch times 1000 (1ms per quarter inch travel) and get .25 * 1000 = 250 inches, about 20 feet per second or 275 miles per hour. So if your puck travels less than 275 miles per hour it should work out fine for you. Not sure how fast it will pick up an object but it's limit should be the time the ADC takes to read divided by 2, I do two ADC reads and throw the first one out so there should be no false triggering.
You do need to light the top with a constant light output, room light is fine but it needs to be over the game so you dont cast a shadow on the sensors. Perhaps put some led's on the rim of the goal or hang lights above the game.
I will program 2 chips and send you 20 sensors and a schematic. You can find the pots and wire up whatever you want for the goal light.
PM me your address.
You could use the high or low signal as input on a stamp to do any other tasks you can think of as well, perhaps turn on a nice little sound chip with some band playing that funny organ music they usually play when someone scores.
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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!
Post Edited (metron9) : 2/1/2007 7:39:51 AM GMT
Just out of curiosity, how are you going to differentiate between the hockey puck blocking the sensor verses shaved ice blocking it?
Regards,
Bruce Bates
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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!
Thank you very much for the help.
TH