I have this circuit wrired to a door so when it opens makes a sound etc however i have some problems with it they are it triggers slightly sometimes on its own even without the door being opened.
any ideas how i can change it to prevent false alarms ?
I have this circuit wrired to a door so when it opens makes a sound etc however i have some problems with it they are it triggers slightly sometimes on its own even without the door being opened.
any ideas how i can change it to prevent false alarms ?
I put a thin piece of break wire across the door across the switch to see if it was the switch not shutting properly and it still triggers the speaker slightly every now and again.
hi,
I would connect the switch from the Base of the 1st transistor to 0V, not the junction of the two resistors.
Also connect a 10nF cap across the switch contacts.
ericgibbs: You're right. The two transistors is connected wrong. If it's intended to be a darlington pair, the forst transistor (leftmost) must be conected to colector and base to the other one.