Need A Proffesional For This Problem : Laser Alarm Circuit

[dragon700000]

Hi EveryBody

I Need Help With This Problem >>> Laser Alarm Circuit


I Built This Circuit

**broken link removed**

& Connected The Out But From The Relay With Police Siren Circuit

http://1.bp.blogspot.com/_Bxy8CibBNak/Scbi22ChpDI/AAAAAAAAAA0/QlHfjt9jj8Y/s1600-h/police_siren2.gif


But I Got a Problem >>>> The Alert Stopping After The Body Crossed The Laser Beam !!

Meanning : The Siren Works Just Only For 1 Second !!!


How Can I Make it To Sound Constantly After The Body Crossed The Beam ??

Some Told Me To Put Thyristor But I Don't Know How 2 Connect It With The Circuit ?

& If There Are Other Soulotion For This Circuit Problem

I Hope I Get An Anwer Cause I'm Very Dispointed Of That Case

- - - Updated - - -

The Laser Alarm Circuit Again

http://www.gulfup.com/?jr0AH3

 

[chuckey]

The easiest way is to wire a spare contact on K1 back to the input of the opamp, via a switch and a 10 K resistor. So the circuit works as it did until the relay is energised, this then routes some voltage via the new switch and 10K resistor back to one of the opamps inputs, so it keeps the relay energised when your target has gone. You will then open the switch to reset the alarm.
Frank

 

[ALERTLINKS]

Try with adding another diode as shown in diagram.