Door Bell alarm Noise

[thannara123]

I made door bell using ISD Module **broken link removed** . it is working well .
I used to battery to hear it . Whenever I installed it on my room . the push switch wire is connected to outsie through electrical wiring . it some time automatically makes sound(it turn ON ) also turn On whenever a spike in main power supply . How to avoid it ?

 

[BradtheRad]

turn On whenever a spike in main power supply

I suppose the push switch wire goes to the IC input? Is it connected to something when idle? Or is it floating when idle?

If not then it may be picking up ambient mains hum. Or it may be triggered internally by instability in the power supply. This sort of thing is likely to cause misbehavior.

I think it will help if you reduce the tendency of the input to turn on. Try connecting a high ohm resistor from the input line to either supply rail. 10k or 100k might be a reasonable value.

 

[thannara123]

input means ?
where i connect the resistor ?
parallel to the push switch .

 

[BradtheRad]

It sounds as though the device is plagued by false triggers.

This shows a common method to stabilize a sensitive input. (Of course it is only supposition on my part that this could be your problem.)



My above post is a description of a pull-down resistor. (Optionally it might need to be installed as a pull-up resistor attached to the supply instead of ground).

Also consider adding a capacitor as shown, to help reduce spikes and noise on the input.

The values are only guesses on my part.