I have been looking at piezo sounders for another project and have looked at how the small 12volt alarms are put together.
The one I have uses a 26mm dia sounder running at approx +/- 110v peak (220v pp).
The high voltage is generated with a small auto transformer switched with a square wave from a 555 timer via a power transistor.
These units are designed to be ultra cheap so I doubt whether any of the components are special. The transformer is ferrite cored and the power transistor is a D313.
The power consumption was approx 200mA @12v.
Running frequency is approx 2.5 KHz
One point you might consider - running the sounder in free air gave a pathetic squeak - fitting it into the alarm housing nigh on burst my eardrums - conclusion - the accoustics of the disc housing has as much effect on volume as the electronics.
Regards
Ron
The one I have uses a 26mm dia sounder running at approx +/- 110v peak (220v pp).
The high voltage is generated with a small auto transformer switched with a square wave from a 555 timer via a power transistor.
These units are designed to be ultra cheap so I doubt whether any of the components are special. The transformer is ferrite cored and the power transistor is a D313.
The power consumption was approx 200mA @12v.
Running frequency is approx 2.5 KHz
One point you might consider - running the sounder in free air gave a pathetic squeak - fitting it into the alarm housing nigh on burst my eardrums - conclusion - the accoustics of the disc housing has as much effect on volume as the electronics.
Regards
Ron
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