Directional Laser Chime

[suicidalmonkey]

Sorry about the subject, I know it's a bit ambiguous but I can't think of anything else to call it.

The shop I work at uses a laser across the door that chimes when someone walks through and breaks the beam.

This gets irritating because it chimes every time someone walks in or out.

I want to modify his setup to include two lasers (10 - 20 mm apart) and set to chime when someone enters the shop and not when they exit.

Can anyone help with a circuit, keywords I can search on google or a different idea such as a PIR detector?

Thanks in advance

 

[akg]

a little bit info . suppose A and B are the two detectors , the vistors going in first pass A and then B
.
ok. when A gets triggered (ie beam broken), the ckt associated with it will enable the o/p of (for a short duration) the sensor B, and it will chime only when A and B are broken sequentialy..and will work only in one direction.

 

[suicidalmonkey]

a little bit info . suppose A and B are the two detectors , the vistors going in first pass A and then B
.
ok. when A gets triggered (ie beam broken), the ckt associated with it will enable the o/p of (for a short duration) the sensor B, and it will chime only when A and B are broken sequentialy..and will work only in one direction.

Thanks akg, thats exactly what I wanted.
I found another thread that answers the same question.
https://www.electro-tech-online.com/threads/capacitance.18451/
Thanks for your help.

 

[akg]

a little bit info . suppose A and B are the two detectors , the vistors going in first pass A and then B
.
ok. when A gets triggered (ie beam broken), the ckt associated with it will enable the o/p of (for a short duration) the sensor B, and it will chime only when A and B are broken sequentialy..and will work only in one direction.

Thanks akg, thats exactly what I wanted.
I found another thread that answers the same question.
https://www.electro-tech-online.com/threads/capacitance.18451/
Thanks for your help.

you are welcome