I Need HELP ASAP With My Electronics Project Please!

Hi. I am trying to build a laser security system. When the sensor and the transmitter are in range and connected, the buzzer and led are off. But when the connection is cut betweens the sensors, the led and buzzer turns on. When the connection is made again between the sensor and the transmitter, the buzzer turns off and the led stays on, which is switched off by a reset switch. This project seems to work perfectly fine in circuit, but when I simulate it in reality, the circuit doesn't work. Can you help me out please.

What simulation software are you using? zip and post your simulation file so that it can be tested. Do you have laser led in the simulator? If yes, place it near the photo-transistor and see if it works.

The + input of IC1 is held at +12V

The - input of IC1 will not go higher than +12V, so there is a good change that IC1 output will be permanently high.

I would have put a potentiometer (maybe 100k Ohms) on the + input of IC1 to provide a variable reference voltage.

I am assuming that IC1 is a 741 op-amp or similar?

jayanth.devarayanadurga said:

What simulation software are you using? zip and post your simulation file so that it can be tested. Do you have laser led in the simulator? If yes, place it near the photo-transistor and see if it works.

Click to expand...

I used circuit wizard 2. You can build this circuit on there in no time.

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hexreader said:

The + input of IC1 is held at +12V

The - input of IC1 will not go higher than +12V, so there is a good change that IC1 output will be permanently high.

I would have put a potentiometer (maybe 100k Ohms) on the + input of IC1 to provide a variable reference voltage.

I am assuming that IC1 is a 741 op-amp or similar?

Click to expand...

this is my As electronics, i haven't quite understood the basics much. The photo diode is there within the circuit to act as a sensor. in real life, i am using an infra-red transmitter and reciever. the photodiode is there to adjust the lux meaning that in real life, it will act as an object blocking the sensors.

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Babar Firasat said:

I used circuit wizard 2. You can build this circuit on there in no time.

- - - Updated - - -





this is my As electronics, i haven't quite understood the basics much. The photo diode is there within the circuit to act as a sensor. in real life, i am using an infra-red transmitter and reciever. the photodiode is there to adjust the lux meaning that in real life, it will act as an object blocking the sensors.

Click to expand...

And yes, the op-amp is a 741