Optical beam break sensors for Skeeball?

[thatpurplestuff]

Hey everyone, I am in the process of trying to replace the mechanical switches in my Skeeball machine with optical sensors.  Quite frankly, despite all of the help that many people here have provided I really have no clue what in the hell I'm doing.

I originally tried some Sharp digital distance detectors, but since I am using shiny black Skeeballs I can't use an IR reflective setup and instead have to go with a beam break setup.  I purchased just the basic photodiodes and LED's for this months ago but the idea of having to mess with resistors for both the emitter and the receiver of 8 switches just seems to be over my head right now.

I think I may have found an option that I will only have to add 10k resisters to each receiver, but I wanted to get some feedback from people that actually know what they are doing before I ordered them haha.  Will these beam break sensors work (meaning send a signal when the beam is broken) if I follow the instructions and put a 10K resister between the red and white wires of the receiver?  I plan on connecting everything to a KeyWiz, and my goal is to have a signal sent to the KeyWiz when the beam of light between the sensor and receiver is broken.  Below is the beam break sensor that I am considering:

IR Break Beam Sensor - 3mm LEDs

https://www.adafruit.com/products/2167

This is the 3mm IR version.  It works up to 25cm / 10". You can power it from 3.3V or 5V, but 5V will get you better range and is what we suggest. The receiver is open collector transistor output which means that you do need a pull up resistor if you want to read a digital signal off the signal wire. Most microcontrollers have the ability to turn on a built in pull up resistor. If you do not, connect a 10K resistor between the white wire of the receiver and the red wire. If you want to control a relay or LED or whatever, it can sink up to 100mA to ground.

My apologies ahead of time to the many people (like Scott) that have been very generous trying to help me wrap my brain around this whole concept.  I'm just completely stuck right now.

[matsadona]

Going from mechanical switches to this solution would probably also require that you change the encoder/interface. Not sure what you have today, if it is an IPAC or similar or if you have built something by your self?

[PL1]

Nice find, TPS.   

Should work great for a skeeball setup. 

Not sure if you'll need pullup resistors -- depends on your encoder.   
(Resistors like these are cheap so you might as well pick some up at Radio Shack.)

I bet you could make some nice mounts out of 1-1/2" (?) L-brackets and tie straps.

Clamp a straight-edge router guide and route a shallow (1/8") pocket the width of the L-bracket on both sides of the hole to align the emitter and sensor mounts.


Scott

[thatpurplestuff]

Thanks Scott, and thanks for your seemingly infinite patience in trying to help me wrap my brain around this entire optical sensor thing haha.  I just picked up a couple packs of resistors so I will have something to tinker around with if the sensors don't initially work out of the box with the KeyWiz... I couldn't remember what wattage to buy so I just picked up both 1/4 and 1/2 (will either of these work?)



I am going ahead and placing the order for these beam break sensors and will make sure to document everything in the Skeeball build thread.  These sensors may work great for other projects as well (like the arcade basketball build)!

[johnrt]

You have bought 10 Ω resistors. You should have bought 10 kΩ! That's a big difference! You can not use the 10 Ω ones!

Also: If you buy them from ebay, you can get like 600 resistors in different values for like 3 dollars.

Edit: and you just need the 1/4 watts ones.

[thatpurplestuff]

You have bought 10 Ω resistors. You should have bought 10 kΩ! That's a big difference! You can not use the 10 Ω ones!

Also: If you buy them from ebay, you can get like 600 resistors in different values for like 3 dollars.

Edit: and you just need the 1/4 watts ones.

Haha great catch!  I completely missed that when I bought them... guess it's back to Radio Shack!  Thank you very much for the info and error checking!

[PL1]

The reason I linked to the 1/2 watt 10k Ohm resistors is because the technical details of the sensor mentions

Output Current Capability of receiver: 100mA sink

100mA * 5v = 500mW = 1/2 Watt

I know it's somewhat over-engineered for normal operation, but they are about the same price IIRC.


Scott

[johnrt]

The reason I linked to the 1/2 watt 10k Ohm resistors is because the technical details of the sensor mentions

Output Current Capability of receiver: 100mA sink

100mA * 5v = 500mW = 1/2 Watt

I know it's somewhat over-engineered for normal operation, but they are about the same price IIRC.

The maximum current through a 10 kΩ resistor at 5 V is: I = U/R = 5/10000 = 0.5mA. The power consumption of that resistor is: P = U x I = 5V x 0.5mA = 2.5mW, that is 0,0025 W

[PL1]

Good catch.

I forgot about the current-limiting action of the resistor.   


Scott

[thatpurplestuff]

haha woah that conversation just went completely over my head (which would also explain why it has taken me so long to even attempt converting over to optical switches).

Thank you both for the help!