# Piezo transducer extreme current

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#### Nicolaii

##### New Member
Hi,
I am doing a project in which i need to power piezo transducer with 140 kHz ~20V signal. When Im powering piezo with generator it only takes 6mA. But when I try to power piezo with my circuit it takes more than 1A. When i place resistor it gets hot and circuit lose power. Where is the problem?
Maybe you could give me advice of alternate ways to power piezo with such a signal?

#### AnalogKid

##### Well-Known Member
Is this your circuit?
How much current is available at the 20 V source?
What is the value of L1?
Do you know why L1 is in the circuit?
Manufacturer / part number for the transducer?

ak

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#### Nicolaii

##### New Member
Current is up to 1.5A
Piezo is 14 nF and inductor 107 uH
L1 is here because of impedance stuff

#### Tony Stewart

##### Well-Known Member
Nicolaii get the RLC Nomograph and look up impedance at resonant f and ask yourself , does f match source and what is impedance of the switch and why does this lower Q in a shunt tank. Try a linear bias current sink sine wave at resonant f instead of a switched square wave and don't saturate L. Add plastic C if f is fixed.

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#### chemelec

##### Well-Known Member
Why 140 KHz?
Will your piezo even operate at that Frequency?
And you also can't hear it.

#### spec

##### Well-Known Member
Hi,
I am doing a project in which i need to power piezo transducer with 140 kHz ~20V signal. When Im powering piezo with generator it only takes 6mA. But when I try to power piezo with my circuit it takes more than 1A. When i place resistor it gets hot and circuit lose power. Where is the problem?
Maybe you could give me advice of alternate ways to power piezo with such a signal?
Hi Nicolii,

give the circuit below a try.

spec

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#### dr pepper

##### Well-Known Member
Yes 140kc is very high.
Increasing the inductance of the inductor will reduce current flow and 'volume'.

#### chemelec

##### Well-Known Member
Which Piezo are you using?
Most Piezo's have a Limited Frequency range of reproduction.
Very FEW of them will do 140khz.

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