•  
  •  

Light Barrier Detector

Designed by Naveen P N

This simple circuit using a single transistor turns ON the relay when light falls on the LDR.
The potentiometer is adjusted for the required sensitivity.
The power supply is 6V.
Be careful about the impedance of the relay. Its impedance should not be less that 60ohm.
Its working can be explained as follows:
With the light falling on the LDR,its resistance is low and the transistor is saturated and turns the relay ON.
When light is obstructed, the LDRs resistance becomes very high. The potentiometer shorts the transistors
base to ground and it is cut off. Hence the relay is OFF.

Tested 11th Jan,2001 by Naveen P Nwebmaster@electronic-circuits-diagrams.com

If there are any problems please contact webmaster@electronic-circuits-diagrams.com

Please share & like

JOHNSON CONTROLS TE-67NP-1N00 / TE67NP1N00 (NEW IN BOX)
$101.5 JOHNSON CONTROLS TE-67NP-1N00 / TE67NP1N00 (NEW IN BOX) picture
Johnson controls metasys
$225.0 Johnson controls metasys picture
Johnson Controls METASYS XP-9102-8304 Expansion Module
$273.92 Johnson Controls METASYS XP-9102-8304 Expansion Module picture
Johnson Controls Metasys NU-BAT101-0 Battery ***NEW** in box
$189.0 Johnson Controls Metasys NU-BAT101-0 Battery ***NEW** in box picture
JOHNSON CONTROLS DX-9100-8454 METASYS PROGRAMMABLE LOGIC CONTROLLER
$19.99 JOHNSON CONTROLS DX-9100-8454 METASYS PROGRAMMABLE LOGIC CONTROLLER picture