My application requires a transducer to generate frequency from 24khz to 34khz with 2Khz steps. It's a 60W transducer and I want to complete this cycle in at max 20 sec. Any ideas?

 

As you only have 6 frequencies to step through you could just load an 8 bit (Or 16 bit counter) with a count that gave a time of half a cycle of you required frequency and each time it decremented to zero out toggle an I/O pin. If you used a PIC microcontroller for example a PIC12F1840 with a 20 Mhz crystal you would have an instruction clock frequency of 5 Mhz (200 nS) that would increment the counter. Here is the start of the calculations for your frequencies.
24 41.67 uS x5 = 208.35 /2 = 104.18 (count 104 gives frequency of 24.04 Khz)
26 38.46 uS x 5 = 192.3 /2 = 96.15 (count 96 gives frequency of 26.04 Khz)
28 35.71 uS x 5 = 178.55 /2 = 89.28
30 33.33
32 31.25
34 29.41

This would not give your exact frequencies but would probably be close enough. For each step in frequency you would just load the counter with calculated value. You could get slightly more accurate timing using a 16 bit counter with one of the Atmel ATtiny range (ATtiny 2313) as the instruction clock is the same frequency as the crystal. (Not divided by 5 as it is in a PIC)

Les.

 

Thank you LesJones. I have one more question though.
My design requires a high power consuming transducer. I want to resonate water molecules at those frequencies for my experiment. Now that you told me to use a counter to generate pulses of desired frequencies my question is how to drive transducer using these signals? do I have to use some power circuit containing capacitors, transformers and voltage regulators to deliver power and data too?? Thank you.

 

I have not worked with ultrasonic transducers. I would start by reading the data sheet on your transducer. The data sheet may include suggested driver circuits. I think most ultrasonic transducers look electrically like a capacitor so you may need an inductor in series or parallel with it to tune out it's capacitive reactance. It is possible that as well as changing the drive frequency you may have to switch in different parallel capacitors for each frequency. I suggest that you Google "Driving ultrasonic transducers".

Les.