Infrared Beam Door Alarm

INFRA-RED DOOR ALARM

INSTRUCTION SHEET

Price - Stock No 245

Transmitter Construction

Receiver Construction

Setting up

1. Arrange the transmitter and receiver about 1 metre apart with the IR LED of the transmitter pointing in the direction of the receiver
2. Orientate the receiver so that the IR decoder is facing the transmitter.
3. Turn the receiver ON - the buzzer will sound.
4. Turn the transmitter on and the buzzer should stop.  If not check the orientation of both transmitter and receiver.
5. If you place your hand (or some object) in the beam, the buzzer will sound.
6. 
   
   
   Trouble shooting

Troubleshooting  if necessary will involve careful checking of locations and polarity of components. Re-solder all joints and check to make  sure  you  have  not  bridged across  between  any  two adjacent component legs.  The end  of  a  broken  hacksaw  blade  sharpened  on  an  emery wheel is a good tool for cleaning between soldered joints.

Technical notes

Looking at the transmitter, the 555 creates a 50 kHz signal which is used to power the IR LED.  This sends a beam of infra-red light.The frequency of oscillation can be calculated using the following formula:

View the Datasheet for the 555 .


When the beam is broken, the transistor is energised and the buzzer sounds.

refer to this site: http://cdselectronics.com/Kits/IR_beam.htm

Contact CdS electronics