From: nojunk@knology.net   
      
   On 5/14/2019 9:18 AM, AK wrote:   
   > On Tuesday, May 14, 2019 at 7:29:08 AM UTC-5, amdx wrote:   
   >> On 5/13/2019 9:22 PM, AK wrote:   
   >>> Electronic can be quite frustrating.   
   >>>   
   >>> I put together a circuit for a laser alarm.   
   >>>   
   >>> It does not work.   
   >>>   
   >>> There is no way to tell if a design will be successful even if you follow   
   the authors exact directions.   
   >>>   
   >>> I will keep plugging away and reading Practical Electronics for Inventors.   
   >>>   
   >>> :-)   
   >>>   
   >>   
   >>     Are you know using the 555 circuit.   
   >>                            Mikek   
   >   
   > I do not understand your question.   
   >   
   > Do you know of any circuit that will detect someone crossing a light path?   
   >   
   > It does not necessarily have to use a laser.   
   >   
   > Andy   
   >   
   I'm surprised you have already forgot about the first transistor   
   circuit you posted and then my response with a google search with 25   
   more transistor circuits.   
     After I posted you answered the question to someone else, yes you are   
   using the 555 circuit.   
     I'm disappointed, you had a chance to learn how to bias a transistor on   
   or off and then see how the changing resistance of your LDR would cause   
   the switch on and off.   
     You should find it interesting to bias a transistor to have the buzzer   
   quiet, change the value of one resistor and make the buzzer buzz.   
     Then put the original value back in with the LDR in parallel and see   
   light make the buzzer go on and off.   
   You were to quick to abandon the original circuit.   
      
                                Mikek   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)