build a infrared controller

[MrKemp]

Please could someone either tell me or point me in the way of a good tutorial on how to build your own Infrared Controller that i could use to turn on a simple LED wireless without having to program any of the components. I dont have a great understanding of electronics but i am trying to learn so please be kind

 

[(*steve*)]

At its simplest, all you need for the transmitter is an IR LED, connected to a battery via a switch and a suitable resistor. The receiver is then simply an IR photo transistor connected to some sort of amplifier and finally to a LED.

Shining the IR LED onto the phototransistor will allow the LED to light up.

However, such a circuit can be triggered by almost anything that emits IR in the band that the transistor is sensitive to (it may also be sensitive to visible light).

To make it less sensitive to plain IR light, you need to place a signal onto the beam that is detected by the receiver. Perhaps the easiest is to modulate the beam at a particular frequency. The receiver can then amplify just a narrow band of frequencies and use this signal to turn on the LED.

 

[MrKemp]

so what parts would i need to build the entire thing as well as modulate the beam so its not sensitive to other Infrared light would it be possible for you to draw me up a schematic diagram i would be more than great full .

 

[(*steve*)]

You would need to be more specific as to why you want to do this (e.g. is it just for your amusement, or is it for some purpose) in order that we can suggest something appropriate.

My initial suggestion for the transmitter is that you look at using a 555 oscillating at around 40KHz, and driving an IR LED with about 30mA. Here is a page discussing something similar. You can increase the range by placing several LEDs in a series/parallel arrangement and/or by using a igher current (check with the specs for the diodes).

For the receiver you'll need a matching phototransistor, and an op-amp with a narrow band pass. (You could also use a dedicated IR receiver as suggested in the link I gave you above).

Another option is to look at this page to design an active filter centred on 40khz with some suitable bandwidth (say 500 Hz). Following this you would want (possibly) to rectify the signal, and a comparator to turn on the output LED when the amplitude is large enough.

As you can see, it's not super simple. If you only want 30 cm of range or so, the circuit can be much simpler.