IR Sensor

Use a shield (say a short cardboard tube over the sensor) to cut out some of the background light and improve directionality.

Too much sensitivity is rarely a big problem, it is generally easy to divide down the output or reduce the gain. Look for appliction notes for your sensor from the manufacturers website.

Del

infact it is a big problem aspecially if you are using a sensor because it could make too much current to flow or less current to flow then your project may not function or blow up

LOL...

I said 'rarely'...I have been designing electronics for a living for the last 35years and was trying to give a quick simple answer...

Adding a cardboard tube is hardly going to blow anything up.
A sensor input stage is also hardly going to blow up...it may saturate the sensor.
It is much easier to reduce the gain/sensitivity than to increase it.

Your suggested solution is complete...oh, sorry, you didn't make any suggestions...

Del

What sensor are you using (manufacturer & part number)?

Use a photodiode (for greater dynamic range and ambient light tolerance), not a phototransistor. Use pulsed LED and an AC amp on the photodiode maybe even gated/synchronous detection. Use a collimator or a lens to limit the field of view. If you pulse the LED and use excessive gain in the photodiode amps you can render the "range" to the target into the time domain (a stronger signal will propagate through the amps in less time) which eliminates the need for gain control and lets you easily use a microcontroller to gage the distance to the target (not precisely though due to variation in reflectance of different surfaces).

a photodiode may work if and only if reciever and transmitter are placed in the same direction , in other word yhey must face each other for their function to take place . this means if you were to use photodiodes you would have to put the reciever on the wall.

thy shall not question the real guru. Electro sta-B

Please stop spouting twaddle.

"a photodiode may work if and only if reciever and transmitter are placed in the same direction ..."

What on Earth makes you think that?

I shall not question you because you are completely clueless. I have designed and built literally thousands of proximity sensors using photodiodes that did not face the LED. I have developed and built diffuse infrared signaling systems that operate at 30 feet in a room with not only no direct line of sight but with occlusions present. All using photodiodes. You need to think outside the box my friend because I think your box is taped shut so tightly that the lack of oxygen is affecting your brain. Thus spoke the Grand Master of IR sensing!

Thou, not thy.

If you're going to use thou, you might as well say shalt instead of shall.

That is all.

Actually no it isn't, guru my arse.

that is all.

use a transistor voltage-divider with your IR-sensor and a variable resistor connected in the base of the transistor , and you can put in an LED in the collector. remember the variable resistor is used to control the sensitiveness of your robot. start with a 10k-100k

Electro sta-B

Do not forget that some sensors are very sensitive to the 50 or 60 Hz mains frequency and your circuitry needs to be designed to filter out and ignore such problems....I had a design problem in this area some 10 years ago that kept me guessing for a couple of days till I put a scope on it, then it was simple to fix......

Use of an oscilloscope is almost a 100% must for such designing by the way, it can save you days/weeks of development time!! There are cheap or secondhand ones around, you will not regret it....

I am not saying you cannot develop electronics without one, it just makes life a lot easier....

You may want to try to leverage some of the infrared remote control technology. Instead of using an IR sensor use an IR Pre-Amp, the difference is the pre-amp only picks up modulated infrared of a specific frequency, typically 38 or 40 kHz. Using a 555 timer its relatively easy to build an IR transmitter of the right frequency. These still do not work under direct sunlight but do work under most indoor lighting.

Shawn