where to get long wires?

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huai
 
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where to get long wires?

Post by huai »

Hello all,

I'm working on my first arduino project - it will be a timer between 2 IR break beam sensors to time the start and end of a race. Essentially 2 of sets of these: https://learn.adafruit.com/ir-breakbeam-sensors/arduino

The issue is that the start and finish line are about 15 ft apart and the cables on the IR breaks sensors are short. Does adafruit (or any other vendor) sell ~10ft long breadboard male to female cables? If not what do you all suggest as the alternative? Also any considerations for signal loss over that distance?

Thanks in advance,
Can't wait to get started w/ Arduino

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adafruit_support_bill
 
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Re: where to get long wires?

Post by adafruit_support_bill »

Breadboards are great for prototyping circuits on a workbench. For your application you probably want some more robust connections. We have some cold-splice connectors here: https://www.adafruit.com/?q=cold+splice&sort=BestMatch

For wire, you could use regular hookup wire. I'd recommend the stranded type: https://www.adafruit.com/?q=stranded&sort=BestMatch

Noise is probably not going to be a problem at that distance. But if there is a lot of interference, you might want to twist together the signal and ground wires to minimize the effects of interference.

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larryf
 
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Re: where to get long wires?

Post by larryf »

Speaking of using these to time races, what is the ms response time of these break beam sensors? If you have something flying by at high speed, it may only be in front of the sensor for a millisecond or less. What does the frequency response of these sensors look like, and how much light has to be blocked for them to detect a break? Are they adjustable at all? Is the output wire essentially analog, (meaning the less light, the less current) perhaps? If so, can the pull-up resistor be changed to make them quicker-responding, or rather to make them trigger when less light is blocked, thus making them more sensitive?

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adafruit_support_bill
 
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Re: where to get long wires?

Post by adafruit_support_bill »

The manufacturer specified response time is <2ms. The receiver is a phototransistor with an open-collector output. Shrouding the receiver to block ambient light can make detection more reliable. Using a weaker pullup might improve sensitivity to some degree also.

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larryf
 
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Re: where to get long wires?

Post by larryf »

Thank you for that! I was considering using these on a project to detect something at high-speed passing in front of it. But then I realized that even the industrial sensors aren't super-fast. It takes special ones to get insane response times. (Perhaps into the laser realm.) I considered placing a small tube, (like a straw) around the receiver to do exactly what you mentioned. Any idea what size resistor might help? Since it's a phototransistor, I assume it's literally just ON or OFF, but maybe changing the resistor will reduce (or increase) when it switches.

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adafruit_support_bill
 
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Re: where to get long wires?

Post by adafruit_support_bill »

The manufacturer specs don't have a lot of detail. But phototransistors in general are analog devices that modulate current in response to light. They tend to be somewhat linear over at least part of their sensitivity range. So varying the pullup resistance should change the point at which the output voltage reaches the logic LOW threshold for your microcontroller.

We usually use a 10K resistor for basic detection. You could experiment with higher values like 20K, 50K or 100K.

We do have a phototransistor that claims a 2uS response time:
https://cdn-shop.adafruit.com/product-f ... 15__1_.pdf

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