a doubt regarding an automatic doorbell circuit?

Question

Here is the link :
www.electronicshub.org/automatic-doorbell-with-object-detection/

I am making this circuit on a pcb but the problem is that none of my local electronic stores have a separate transmitter and reciever like shown in the circuit diagram. What they do have is a 'HC SR-04' ultrasonic transmitter - reciever ( 4 pins - Vcc, trig, echo, GND). And I have no idea as to how I am supposed to attach this to the circuit in place of the transmitter and reciever shown. I dont know which connection goes on which pin. Anyone have any ideas? I am trying to this as a project for school.

? · Answer

I agree there are too many mistakes to build this circuit. Try the circuit in the source, it looks much better to me.

? · Answer

I have seen this contraption before.  It contains at least one error. (why is the output of the receiver shorted to +9 volts).  This will likely destroy the receiver.

What is the photo isolator for?

The whole mess looks more like a classroom exercise in a number of circuit schemes, not as a practical device.

The 'transmitter-receiver' device you mention is a small circuit board with a transmitter and a receiver.  The four pins are Gnd, power (5 volts?) trigger out, signal in.  It is intended for ranging.

Suggest you desist...this piece of junk will not work.

oldschool · Answer

You can see on the circuit that the transmitter and receiver have a common wire.  Most likely the combination device has at least tree wires: send, receive and common.

Anonymous · Answer

You don't say where you are, but Maplin in England has ultrasonic transducers which are sold as a transmit and receive pair. You would need someone in England to buy them and ship them to you as Maplin do not ship outside UK and Republic of Ireland.

http://www.maplin.co.uk/p/40-khz-ultrasonic-transd...

http://www.maplin.co.uk/p/40-khz-ultrasonic-transducer-hy12n

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a doubt regarding an automatic doorbell circuit?

4 Answers