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Infrared Emitter and Reciever

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rfggfd

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Hi,

I'm having trouble making an ir transmitter/reciever circuit. It is meant to be a parking sensor. Here are the diagrams I am using:

Parking sensor circuit
**broken link removed**
**broken link removed**

I made this circuit on a breadboard, and I'll upload the pictures later when I get home. My problem though was that the 555 timer immediately heated up, indicating something was wrong. One thing that I did do different was that my R3 in the transmitter circuit was 100ohms instead of 33ohms, as we don't have any 33ohm resisitors.

The emitter and reciever im using are from here: **broken link removed**

I made sure to point the emitter right at the reciever. But still no luck. If any more information just ask. Hopefully someone knows where I've gone wrong..
 
hello

Hello,

Do you have detailed calculations of the components values and explanation of what each components do?

Hope to ave a reply from you asap.

Thanks.
 
Welcome to ETO, rfggfd!
Are you sure R3 is only 33 ohm? 330 ohm would make more sense, though it depends on the specs of your LED. If I my math is correct, that would mean the current through the LED is (V=IR) 12=I(33), I=.3636A, or roughly 364mA. That seems rather high for an LED. Giving us the specifications of your LED would help a lot.
Der Strom
 
Last edited:
Hello,

Do you have detailed calculations of the components values and explanation of what each components do?

Hope to ave a reply from you asap.

Thanks.

As far as I can tell, kencool1, the circuit is basically just a comparator circuit that measures the intensity of the light detected by D2 and illuminates D5, D6, and D7 accordingly. It appears that IC2a acts as a sort of amplifier to amplify the signal from D2 and feeds it into IC2b, IC2c, and IC2d, which compare the intensity with preset values. That is how the circuit appears to work. I hope this helps your understanding.
Der Strom
P.S. Welcome to ETO! :D
 
Hi,

I'm having trouble making an ir transmitter/reciever circuit. It is meant to be a parking sensor. Here are the diagrams I am using:

Parking sensor circuit
**broken link removed**
**broken link removed**

I made this circuit on a breadboard, and I'll upload the pictures later when I get home. My problem though was that the 555 timer immediately heated up, indicating something was wrong. One thing that I did do different was that my R3 in the transmitter circuit was 100ohms instead of 33ohms, as we don't have any 33ohm resisitors.

The emitter and reciever im using are from here: **broken link removed**

I made sure to point the emitter right at the reciever. But still no luck. If any more information just ask. Hopefully someone knows where I've gone wrong..

Oh that means you have made a wiring mistake, or the 555 was previously fried, I have lost lots of them 555 timers :S
Are you sure the power supply supplies DC voltage at the right voltage(12volts)?

-Ben
 
The datasheet for the 555 shows that when its load is 100mA then its output typically has a 2.0V voltage drop. The IR LED has a typical forward voltage of 1.3V at such a high current so your 100 ohm current-limiting resistior limits the current to 87mA.

The 555 is turned on for 91% of the time so it heats with (0.91 x 2.0V x 87mA)= 1.38W. Its max allowed heating is 1.18W so it is overloaded in your circuit and will quickly fail. In the original faulty circuit with the 33 ohm resistor the 555 will be much hotter.
 
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