blogbo Posted October 4, 2005 Report Share Posted October 4, 2005 Hello folksfirst time poster here Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 5, 2005 Report Share Posted October 5, 2005 Hi Blogbo,Welcome to our forum. ;DI assume that you are using the 555 timer in its "monostable" mode, so when it times-out it remains sounding the alarm until its timing is started again with its 'trigger" input.Use an NPN transistor to externally discharge its timing capacitor when the motion detector detects motion. Use a resistor from the trigger pin #2 to the positive supply to keep it high until you ground it when you start the circuit. ;D Quote Link to comment Share on other sites More sharing options...
blogbo Posted October 5, 2005 Author Report Share Posted October 5, 2005 Hello AudioguruThanks for the reply Quote Link to comment Share on other sites More sharing options...
blogbo Posted October 5, 2005 Author Report Share Posted October 5, 2005 Helo folksConnecting pin 2 & 4 does solve one problem Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted October 5, 2005 Report Share Posted October 5, 2005 That sounds very strange.Could you post your circuit, it should look something like this.A negitive pulse on the trigger should start the timer and the output should goe high, then when the reset is grounded the output will go low.By the way if the trigger is grounded for a significant period of the delay it can upset the timing, for example if the delay is 1 second and the trigger pulse lasts for 2 the output will remain on for 2 seconds, to avoid this you can a capacitor and resistor to the trigger pin, just ask if you're unsure. Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 5, 2005 Report Share Posted October 5, 2005 Don't reset it with its reset pin #4 or the alarm will sound.Like I said before, "Use an NPN transistor to externally discharge its timing capacitor when the motion detector detects motion". Then it re-starts the timing without the alarm.Trigger pin #2 needs activation only at the beginning and to reset an alarm. ;D Quote Link to comment Share on other sites More sharing options...
blogbo Posted October 7, 2005 Author Report Share Posted October 7, 2005 Thanks for the replies ;DRE:"Use an NPN transistor to externally discharge its timing capacitor when the motion detector detects motion".hello AudioguruYep thats exactly what im looking for ... :)But could ya explain in more detail how this NPN transistor is connected in circuit .... Or even better scribble me a diagram ;)Many thanks Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted October 7, 2005 Report Share Posted October 7, 2005 By the way, sorry about my previous post, I didn't know what you meant but I get it now.A positive pulse at the base will turn on the transistor and discharge the capacitor. Quote Link to comment Share on other sites More sharing options...
ECET0purdue Posted October 7, 2005 Report Share Posted October 7, 2005 ya ...what he said Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 8, 2005 Report Share Posted October 8, 2005 Alun's transistor is all you need.What's it for? To wake sleeping drivers? ??? Quote Link to comment Share on other sites More sharing options...
blogbo Posted October 8, 2005 Author Report Share Posted October 8, 2005 Thanks for all your help guys Quote Link to comment Share on other sites More sharing options...
blogbo Posted October 14, 2005 Author Report Share Posted October 14, 2005 Thanks guys Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 14, 2005 Report Share Posted October 14, 2005 Nice goin', Blogbo! ;D[move]Yahoo! Yahoo! ;D[/move] Quote Link to comment Share on other sites More sharing options...
login
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.