IR relay ?

Just out of interest - has anyone ever tried making an Infrared 'relay'. What I mean is it receives an IR signal via a sensor and then transmits the signal via a IR LED.

Just wondred if anyone had tried it. Could have uses I guess - control your telly round corners, being a less sensible one !!

As in an IR repeater or IR extender? Like they made commercially?

ylp88

Not yet, but I'm thinking about doing one.
My requirement is to convert from one protocol to another such that a particular remote I have can control other equipment without resorting to "invasive surgery".
To simply work around corners, how about IR Rx, buffer/driver(two trannys) IR Tx (LED). PICAXE is probably overkill for a direct relay! Even an RF link can probably be done almost by direct connection to the RF modules.

I didn't realise commercial products existed already - I need to get out more ;-)

Yes I think 'IR repeater' would be a better description that 'IR Relay'

I'm just mulling over what's possible and possible uses. I always think there's a lot of potential with IR links.

Are there any fundamental reasons why IR won't work outside? What distance is practical ? I'm thinking I could use IR instead of radio to retrieve sensor readings from my garden, with a couple of repeaters. Radio works, but IR repeaters could potentially be very cheap in comparison.

IR does not work well outside. The reason is that sun light contains very high levels of IR. This tends to saturate the receiver. If you "stop down" to prevent saturation, then the genuine IR signal is so weak in comparison it cannot be distinguished.
Might be worth experimenting with if it is not in direct sun-light but range will probably be very limited.

Plenty of commercial units available in UK. (MAPLIN and the like), often as part of 2.4Ghz video sender. Usually use 433Mhz to re-send the IR signal. Frequency is probably country dependant based on local legislation.

Thanks Beaniebots.

I think I'd like to try some outdoor experiments when I get time. My thoughts are that if narrow tubes were used then effects of sunlight could be eliminated??

I looked it up on google and it seems that an IR repeater system will cost a minimum of $20 US. These are usually recievers wired to a transmitter farther away.

With 08M's being os cheap (relatively) a few of them, or even jsut one if you jsut want to take the signal and relay it immediately again, I dont see it as overkill at all. Making your own would end up being cheaper and more fun than jsut buying, and you could program it to work in jsut about any way across any medium you want.

In essence, instead of someone else selling you what they think you need, you can build exactly what you want, and more or less for cheaper than you could buy it. This sounds like a very interesting idea!

--Andy P

Unless using Sony IR Control Codes or needing to do protocol conversion ( and the options are limited ), a simple non-PICAXE solution may be more effective. It really depends upon what IR protocol is being used; a PICAXE in a tight loop won't be able to pass on signal changes less than 500uS in duration, and would probably still need some modulation for the IR LED.

I'm sure narrow tubes will help but it may end up very alignment critical. Probably not a problem if securely fixed in a suitable place but be aware of Stan's warning in an ealier post about creepy crawlies moving in.

Thanks everyone. One idea is a set of temperature sensors each one passing it's reading to the next via IR until it reaches a unit at (hopefully inside) my window. Each temperature sensor unit consisting of an 08M, IR photodiode and IR LED and its own battery.

I know it sounds very critical to get alignment right(and I know 1-wire technology could do the same with a wire, at least for DS18B20 temp sensors) but it still fascinates me.

(and the price. IR sensor about £0.49, IR LED about £0.47, 08M (from 5 pack) about £1.53, dsb18b20 temp sensor about £2.34 - total 'temperature repeater' about £5 ish)

Edited by - Jeremy leach on 7/26/2005 7:48:23 AM

As suggested by Hippy, for a simple repeater I'd dispense with the 08M and use a simple driver. Something like the good old 74C14 paired up for extra drive at a cost of 20p or two transistors as I suggested earlier.