Hi guys, i am currently working on a new project trying to get a high sound output from a transducer I have been given. My only problem is that i am limited to the amount of current I am allowed to use.

I am trying to this in as simple a way as possible because i dont have much space to work with on my final circuit board.

My limits are 13v and 85mA from the drive circuit/220uF capacitor. I also have to use the 165R resistors as shown.

I have been trying to change Q1 with different transistors/darlingtons to get a better gain but so far the best output achieved is 97dB, and I am aiming for around 105dB.

Any suggestions or comments would be welcome.

 

If the transducer current is limited by the 165R resistors then no amount of twiddling with the transistor will increase it . You would have to increase the supply voltage, e.g. by providing a negative voltage on the transistor emitter.

 

If the transducer current is limited by the 165R resistors then no amount of twiddling with the transistor will increase it .

I was wondering would the gain of the transistor or some other factor not affect it? I have tried around 10 different versions and have a range of outputs between 89 and 97dB

 

You say "i am limited to the amount of current I am allowed to use." So how do you expect to be able to raise the sound level?
What sort of transducer is it? A naked piezo disc? If so, a bridge circuit could double the voltage swing across the transducer, but any increase in power implies an increase in current.