How many IR receivers can I wire in parallel?

Projects General Guidance
1

This is my third post related to the laser tag project concept.

I have everything fleshed out in my head, except for one thing.

The receivers that the player wears use an array of TSOP38238 (or similar) IR receivers to take in the signal from the laser beam. The laser is slightly diffused before it hits the receiver array, providing more coverage.

The problem I'm facing is simple. How many of these receivers can I conceivably give a common output, ground, and power input before they stop working? They will be powered via the Arduino 5V pin. I've seen it done with up to four receivers online, but what about 20-30?

Each module has an internal 30k ohm pull up resistor.

Usually the answer I get on these sorts of things is "test it yourself" but I don't have 100 IR receivers or a PCB to mount them in yet.

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2

The data sheet will tell the consumption of Icc, the current used for the 5 volt logic.

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3

I'll take a look now.

EDIT - Power consumption is 10mw. It does not say specifically how many milliamps/volts.

EDIT - Here's the datasheet: https://www.vishay.com/docs/82491/tsop382.pdf

EDIT - Looks like the TSOP38238 operates at 940nm and I need 850. Back to Google.

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4

By the way, if I did get my hands on a ton of receivers, what would be the testing process? Just line them up on a breadboard and see how many of them it takes to halt their output?

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5

10 mW from 5 volt gives me 2 mA. 10/5 == 2...
50-100 sensors wold be okey.

6

You will need a ton of inputs I would say...

7

And neither does anyone else. You are the only one considering such a device.
Paul

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8

So kind of you to supply links to the other two. Do they contain more information than this one?

Your idea of connecting the outputs of these chips in parallel is an alarming hack, they were not designed to do this, hence there is no current capacity of the output transistor in the data sheet. If you wire lots in parallel then what happens is that you end up blowing up the output transistor in the one receiving the data until they are all blown.

Will you be using the recommended circuit of capacitor and resistor between the 5V supply and this chip? If not you will run into difficulties much sooner, even with one chip.

These chips are designed for a modulated light source sending data, are you sure this is what you want, I imagine you just want to detect a hit.

9

Would you not need each IR receiver output to have its own dedicated pin?

If a player were to be illuminated by 2 different "signals" from 2 different opposing players at the same time, then would the decoded signals not interfere with each other if all the outputs were commoned together? Or am I missing some detail....

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10

I want to send and receive data as you normally would.

And yes, I can integrate spots for resistors and capacitors in the PCB.

11

I'm planning on putting a delay of a few seconds after a signal is received. If it were at the same time, yeah there would be interference, but I'm only intending to make two of these.

12

I'm not asking for people to go out and test it, I just want to know if anyone knows how to check IF it will work.

13

How to check is to start with one. If it works, add a second and test them. Continue up to 100.
Paul

14

I don't have any at the moment. I'll order them as soon as I can after I know I'm not doing something horribly wrong.

15

First Post

Second Post

Here's the last two posts about this project.

16

But you never actually DO anything.
Paul

17

I'm 13! Even a $10 order is a rather significant purchase.

18

So I found out that 850nm light won't reliably trigger the receivers, so I think I'm going to use a 980nm laser instead.

19

Each time you add another device, you are putting another 30kΩ in parallel with the internal 30kΩ load resistor.

This means that the effective resistance of the load will keep decreasing as you add more and more devices.

You might get to a stage where any of the output transistors can not take the output fully low, so the Arduino will always see it's input as high.

Or you might get to the stage that Grumpy Mike postulated in reply #8.

So, as Clint Eastwood said in Dirty Harry,
"You've got to ask yourself a question: 'do I feel lucky?' Well, do ya, punk?"

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20

I don't need like 100 of them, only around 20-25.

I guess my only choice is making a purchase then.

Also, no.