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[on:]

For my first Arduino project, I'm trying to make a buzzer system like the ones used at quiz bowls. I'd like to have at least 3 wireless controllers, and when one of them buzzes in, the appropriate LED on the receiver lights up and the other buzzers are locked out until the system is reset. I don't have a lot of electronics expertise, so I'd like to get some advice on how this could work.

First, is an IR led/receiver a good option for this? The buzzers are for classroom use at a range of up to 5-10 yards, so if anyone has any specific hardware recommendations, I'd love to hear them.

How do I get the receiver to differentiate between the controllers? My first thought was to blink the LED at different use different frequencies, but I don't know how to go about detecting this. Is this a reasonable approach?

I'll have plenty more questions on the details later, but first I'd like to ask if the idea itself is sound. Any advice appreciated!

[Reply #1 on:]

You can get IR receivers that use different modulation frequencies like the TSOP113x series, where the x is a single digit giving the modulation frequency, from 30KHz to 56KHz.
If each handset uses a different modulation frequency then each receiver will pick up only one handset.

[Reply #2 on:]

Sounds like he wants one receiver and multiple transmitters tho. RF would be better for range also, and allow setting up on opposite sides of a stage for finals or something.
I have a remote that transmits via RF with sparkfun 434 MHz TX to a RX. I have a 2nd TX also, am gonna build up another remote and see how much they interfere with each other (or, how reliably the transmitter sees both) using Virtual Wire.  Stopped at Staples tonight on the way home to get a little 0.2L box to put it in.

His remote transmit device could be as simple as 1 promini (or RBBB to be a little less money), 1 Tx module, 1 momentary button, and a battery.
Arduino is in powerdown sleep mode all the time, button press creates hardware interrupt to wake it up & transmit a character (read from 3 inputs with internal pullups, pull a different pin low on each to make it unique) over the RF.
Can be like jeopardy, ignore anything pressed too early.

[Reply #3 on:]

To avoid interference, and looking at it a bit laterally.

Have each desk have a box with a button, a cheap  transmitter and  receiver, ( all on the same frequency and code if using encoders ) and a light/buzzer.

In fact you wouldn't want any coding, just monitor the change in the signal strength output of each receiver.

The button will light the lamp  and the transmitter will send ONLY if the receiver is not receiving anything (you can have the transmitter run for several seconds to see who was first, it will block any others)



That's the basic idea, off the top of my head...