controlling electric bells by microcontroller 89c52.

[tapu]

Dear all,
I am controlling 230v ac electric bell by 89c52.by using relay 12v DC (5A).Now i want to add two bells then how to connect bells parrellel or series?is 5A relay enough ?

 

[FvM]

A 230V AC bell should be operated with rated voltage each, so which connection scheme is appropriate?

For relays rating, you should review the bell specification. Please consider that the relay must be rated for 230 VAC and respective current and VA (of two bells), not just current.

A AC bell is an inductive load, you'll want to reduce contact sparking by suitable RC snubbers or varistors. Otherwise relays lifetime may be short and generated noise will possibly upset your microcontroller.

 

[tapu]

Thank you for reply.electric bell does not have specifications (except 230v).how to know current of a bell?

 

[FvM]

A respective German product (Friedland Gong) is specified with 3000 ohm coil resistance and 40 mA AC current.

 

[tapu]

Is theire can be used for school purpose?

 

[thannara123]

Yes you can connect parallel.

 

[tapu]

Thank you for reply, I want to know the wattage of electric bell which can be used in schools.

 

[thannara123]

That is in accordance with the specification requirement by you ..

 

[tapu]

Actually I have one school electric bell.in which specifications are not given.then how to know the wattage /current of bell.which is required for project.