Build your own IR detector

Let’s have a look at the result!

Check our my last tutorial to see how it works (theory and example).

https://oscarliang.com/infra-red-detection-and-photo-transistor-testing/

first of all, test all the components make sure they work!

Let’s do some calculations, and design the circuit, Here is my Schematic:
 

build it on the strip board… This took me 3 hours!! but I am getting better at it ; ) i can tell.

The whole thing costs me:
8 x tcrt5000 = £3.4
1 x strip board = £1
Terminals = £0.5
1 x BJT = £0.5
Resistors and wires = £ 1
 
Total about £6.
When I finished and testing, realised R6 – R9 are too small, (voltage at the collectors of the phototransistors are too small), I decided to take the 4.7k resistors off and replaced with 22k. but it doesn’t seem to improve a lot…
This is what I got at the end.
 
The range isn’t as good as I expected, it’s probably the size and ratings of the LEDs (3mm), however I have ordered some 5mm, and I will probably use more LEDs to try to improve it, but this is good enough to be used for obstacle avoiding.

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