Wireless Piezo Beeper

Posted on Feb 6, 2014

The design is based around a pair of 433MHz wireless modules. These can be bought pre-built and contain all of the radio frequency components that we need. We use these modules in our two circuits; one to transmit our vario audio and the other to receive and reproduce it. It is worth building the receiver first because it can be used to test the

Wireless Piezo Beeper
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Wireless Piezo Beeper - image 1
Click here to download the full size of the above Image.

transmitter circuit. The receiver circuit receives the radio signal and demodulates it into something resembling our vario`s audio signal. This is used to drive the receiver`s own piezo which is located closer to our ear than the vario is. The schematic is shown below. When the battery power is on and there is no transmitter operating nearby, the piezo should produce some audible noise. This is a simple way to test that the receiver is working. Also, when we turn our vario off, the noise reminds us that the receiver battery needs to be turned off too. Veroboard can be used to connect the various components. The layout which I use is shown here. I use a modified 2xAAA battery holder as an enclosure for the circuit and glued it to the back of a 9V battery holder as shown in this photo. Some helmets like the Icaro 4-fight have tail compartments which are ideal for mounting the receiver. In this situation the piezo can be mounted on the receiver`s enclosure. It should not be located adjacent to an ear or it will be too loud. The battery switch can be installed somewhere accessible on the helmet. If there is no suitable place on your helmet it is possible to mount the receiver somewhere in your harness. The piezo can be placed on longer leads if necessary so that it can be placed near your head. It should be possible to hear the piezo if it is placed on the shoulder straps. This circuit takes our vario audio signal and...

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