Infrared transmitter/receiver ?

[Zucker]

I am in the process of making an infrared transmitter/receiver circuit. The
transmitter is made up of an infrared LED in series with a 180 ohm resistor.
The receiver is made up of infrared transisitor in series with a 50k pot.
The junction of the transistor and pot is sent to the input of an LM324
configured as a comparator.

I can only space the transmitter and receiver two feet apart before the
comparator's output goes from high to low.

I need the circuits to be four to six feet apart. Does anyone have any
suggestions on how to increase the distance?

Thanks
Steve

 

[Zucker]

I forgot to mention that both circuits are running off of 9V batteries



"Zucker" <zuckuss@comcast.net> wrote in message
news:OoVJc.19808193$Id.3278430@news.easynews.com...

I am in the process of making an infrared transmitter/receiver circuit.
The
transmitter is made up of an infrared LED in series with a 180 ohm
resistor.
The receiver is made up of infrared transisitor in series with a 50k pot.
The junction of the transistor and pot is sent to the input of an LM324
configured as a comparator.

I can only space the transmitter and receiver two feet apart before the
comparator's output goes from high to low.

I need the circuits to be four to six feet apart. Does anyone have any
suggestions on how to increase the distance?

Thanks
Steve

 

[John Fields]

On Fri, 16 Jul 2004 18:47:10 GMT, "Zucker" <zuckuss@comcast.net>
wrote:

I am in the process of making an infrared transmitter/receiver circuit. The
transmitter is made up of an infrared LED in series with a 180 ohm resistor.
The receiver is made up of infrared transisitor in series with a 50k pot.
The junction of the transistor and pot is sent to the input of an LM324
configured as a comparator.

I can only space the transmitter and receiver two feet apart before the
comparator's output goes from high to low.

I need the circuits to be four to six feet apart. Does anyone have any
suggestions on how to increase the distance?

---
1. Get an IRLED with a narrower beam.
2. Get an IRLED with a higher power output.
3. Pulse the LED you're now using close to its maximum current/duty
cycle limit.
4. Collimate the output of the LED you're now using.
5. Match the LED and phototransistor's wavelengths.
6. Drive the LED with a 40kHz carrier modulated on-off and use a 40
kHz receiver to recover the modulation.
7.
--
John Fields