how to increase the range of an IR transmitter

[timothy]

hello peeps, i built an IR transmitter with CD4069 hex inverter but it doesn't go very far. i do i buffer or increase the range of the IR transmitter?

 

[Nigel Goodwin]

hello peeps, i built an IR transmitter with CD4069 hex inverter but it doesn't go very far. i do i buffer or increase the range of the IR transmitter?

You don't give much information?, but a CMOS inverter isn't going to drive an IR LED very hard - if you check my PIC IR tutorial hardware you'll see how to use a transistor to drive the LED with much more current, in fact I use two LED's in series to double the output, and reduce the power wasted in the current limiting resistor.

 

[Someone Electro]

The feq. must be also be exsactly the one of your reciver.IR modules "see" only its rated feq. it will ignore all other freq..

So if your freq. is off a bit it may reduce range.

 

[Nigel Goodwin]

The feq. must be also be exsactly the one of your reciver.IR modules "see" only its rated feq. it will ignore all other freq..

So if your freq. is off a bit it may reduce range.

All those I've seen are fairly tolerant, usually about 38-40KHz works fine .

 

[audioguru]

Some IR modules reduce their gain if the modulated IR is continuous, to avoid interference from compact florescent bulbs that operate at the same frequency. Therefore they need to be pulsed at a slow rate.

 

[John walker]

You could try adding lenes , like those in the eye focus units on bynoculas
many of the homemade designs for burglar alarms used them to increase the range in the past

Pulsing the signal at a higher freq could help but ive no experiece in that area .

MY thoughts would be to drive a power transistor stage from the 4069 and add more IRs to up the power radiated.

 

[haxan]

Nigel, In your hardware section of your website where you have a circuit for IR communication, You use a 5V supply. What should be the value of the Cap (470uF) if i want to design it for two pencil cells (1.5V x 2 = 3V total). My IR remote works fine for 5V but the range is lost when i use 3V supply. I am using PIC18F2220 (if that matters somehow)

 

[Nigel Goodwin]

Nigel, In your hardware section of your website where you have a circuit for IR communication, You use a 5V supply. What should be the value of the Cap (470uF) if i want to design it for two pencil cells (1.5V x 2 = 3V total). My IR remote works fine for 5V but the range is lost when i use 3V supply. I am using PIC18F2220 (if that matters somehow)

For 3V use only a single LED - the exact same electrolytic is fine.

My 3V version uses a 0.68ohm series resistor, with a single LED.

 

[haxan]

I already have one LED. How about just removing the resistor. I do not have any resistor less than 39 ohm.

 

[Nigel Goodwin]

I already have one LED. How about just removing the resistor. I do not have any resistor less than 39 ohm.

No, you MUST use a current limiting resistor, and it must be very low to give decent range - not using a resistor at all is likely to blow the transistor or LED..