Chosing one two buzzers

[hasanbacioglu]

Hi guys,

I wanna design a simple circuit using demux. What I wanna do is to be able to active only one buzzer at a time. ( Two in total.) If the first buzzer fails, second buzzer should be operational. ( Kind of back-up). What kind of design, circuits element am I supposed to use. Any kind of help would be greatly appreciated. ( I dont want to connect 2 buzzers in parallel and hope seconda one keeps on working if one fails. If first fails, second should be operational.)

Thanks in advance for your kind attention.

 

[KMoffett]

We need specifications on the buzzers. What failure modes do you anticipate...how will you know they failed?

Ken

 

[hasanbacioglu]

Hi Ken,

It will be Sonitron SMA-24L buzzer. **broken link removed** specification. I don't know how to detect failure. I had know I would try to use it as inputs of demux.

Thanks for your kind attention.

 

[KMoffett]

OK, can you provide a schematic of the circuit that controls this buzzer?

Ken

 

[hasanbacioglu]

At the moment I dont have drawing for controller. It is driven by 2 output pin on a board. Snd+ and Snd- as expected. I ll try to send it if I can get it.

Thanks for your attention.

 

[hasanbacioglu]

here is the schematic. I hope it helps.

 

[iukhan]

View attachment 86449 here is the schematic. I hope it helps.

wanna design a simple circuit using demux. What I wanna do is to be able to active only one buzzer at a time. ( Two in total.) If the first buzzer fails, second buzzer should be operational.

One easy method you can adopt is, sense the collector voltage of transistor
it should be HIGH before activating the buzzer and LOW after the buzzer.
If you don't get this it means that it indicate the failure of buzzer so switch to second (backup) buzzer.

 

[KMoffett]

[/QUOTE]
.....
One easy method you can adopt is, sense the collector voltage of transistor
it should be HIGH before activating the buzzer and LOW after the buzzer.
If you don't get this it means that it indicate the failure of buzzer so switch to second (backup) buzzer.[/QUOTE]

This would assume that the buzzer fails "open". The problem with fail-safe designs is allowing for all possible, or at least the most likely modes of failure. Since these buzzers have internal electronics, they could fail but still act as a valid collector load. The only valid failure indication would be no sound when the buzzer is driven.

The schematic posted in too small to read the annotations. I don't see where the buzzer is connected.

Ken