# Estimated impedance of a 12V bleeper?

The bleeper(buzzer) I am using is rated for 12 volts DC. It is a piezo electric bleeper and the frequency is created by an internal oscillator.

I am not aware with the functioning of peizo electric bleepers due to which I am not sure whether my estimate of 600 ohm minimum impedance is correct. My multimeter is not able to measure the resistance of this bleeper.

My question is, to calculate the impedance of this device, would it be safe to say that these type of devices consume at max 20mA? This would make the resistance a minimum of 600 ohms.

Have you come across small(around 1.5cm dia) bleeper that use more mA than this? Do most of them consume less mA than this?

If it is any help, I attached this bleeper to a 220uF capacitor charged at 15V and the sound lasted for about 3 seconds.

• I've had similar beeper (from description) which consumed 50 mA. You said you have a multimeter. Why not just connect it to a 12 V power source and measure the current going thought it? Also we can't really help you too much with the sound, since such beepers will actually produce sound at voltages lower than nominal and that voltage will depend on actual unit. Also are there any markings on the beeper? Only way to be sure about it is to get the model number and find the datasheet. May 31, 2013 at 16:30
• A datasheet would tell you the current rating of the part. May 31, 2013 at 16:33