Posted by cognoscis on October 3, 2008
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Modulated IR sensor
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This entry was posted on October 3, 2008 at 9:45 pm and is filed under Robotics.
Tagged: IR, Modulated, sensors. You can follow any responses to this entry through the RSS 2.0 feed.
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MorpHy said
Hy! I have a problem…i did connect all the wires as shown in the schematics, but the output is very low, it’s about 13mV, and it can’t switch on the transistor! Any suggestion?!
cognoscis said
MorpHy:
The circuit is a simple amplifier. The resistance R3 which is 4.7kΩ controls the base current. Hence, you can reduce it to get more current across your LED. You can reduce its value to as low as 300 Ω without any problem. This will increase the collector current equivalently. Further reduction must be done carefully as there will be chances of the transistor being damaged.
Hope this helps
Also, to increase the range, do send the signals in bursts as explained by using a second timer at 1 kHz.
MorpHy said
Well, the problem is that the output of the 555 it’s about 13mV! I changed the 555 circuit but the problem persists! I changed the resistors: R1=120Ω and R2=180Ω, but i used the same capacitors C1 and C2. I rechecked the schematics and the way I soldered the parts, and it’s ok… Any idea what should i try next?
cognoscis said
Yes,
You see the resistance 4.7 k will have more voltage drop across it. Meaning, less voltage to send the transistor to saturation. Hence, you need to reduce this resistance and you will be able to achieve proper biasing…
Try reducing the resistance. It will definitely work. Reduce slowly. I think about 2.7 k will give you the desired results.. For more range, you can still reduce R4 from 47 Ω to 22 Ω. This will also give you proper biasing
Regards
How to make a PCB at home « Cognoscis said
[...] The breadboard has a circuit to generate 38 kHz IR signal for modulated IR sensor explained in my previous post. The second picture is a part of LDR sensors I made for my line follower robot. The picture has a [...]
krish said
Hi cognoscis.
great entries, and clear explanations. thanks! can you recommend WHICH shop on SP road (what a mess THAT place is) carries the TSOP17 series receivers and how much they cost? I went there but the few shopkkeepers with any knowledge whatsoever were to scatter brain-busy to help.
thanks again,
cognoscis said
There are many who keep TSOPs in stock. OM electronics just at the entrance is the most popular one. Then there is Vishal Electronics. Then there is Balaji electronics, it is in Mandi Veerappa lane, you have to take a left turn near Vishal Electronics to go there, its in the parallel road behind vishal. Then there is Sunrise which is opposite to Vishal. Many other too have it. The cost varies. I got the cheapest in Balaji where it costed me around 45 per piece