I am trying to connect a set of 10 ultrasonic transducers, these are small transducers similar in looks to the range finder types, so not very powerful. The driver is practically this circuit I was thinking parallel configuration? I would imagine I would get more powerful output if I put an inductor across the transducers... I will start experimenting with inductors but was wondering the what the values should be. Looking at some ultrasonic cleaners they have large inductors on them, I know they are much more powerful devices, just trying to scale it for my little transducers.

Transducer specs:

Nominal frequency: 25.0 ± 1.0KHz
Sound pressure: 112dB min.
Sensitivity: -67dB min.
Static capacitance: 2400Pf ± 20%

 

Connecting 10 in parallel may not achieve the effect you want, if you are aiming at increased output. Each transducer will have its own resonant frequency, so a single driving frequency would drive some transducers efficiently and others inefficiently. Output power drops off significantly if the frequency is off-resonance.
It is common to have self-resonant drivers, where the transducer itself is the frequency-determining element.

 

At 25Khz with2400pF, thats 16milli Henries.

 

Alec_t, I tried 1 transducer, then 2 then 3, each added about 40% to the output. I am sure you are right, will make another bridge and see how that effects the total output. At the moment it runs on 40mA with the little transducers. Tried inductors of various size, 100uH up 330uH and not sure just yet I think a 1.6mH no difference in the output regardless of the inductor. But I have some twitters and pest replant transducers that i am also trying and inductors increase their output. I guess the little ones are running at their max?
I just want to make a lot of ultrasonic sound in a room say 5mx5m. And maybe modulate the ultrasonic a little.

Dodgydave, yes, thank you for that.