Summary

1) The new driver board works

2) An ATX supply makes a good DC supply for the driver

3) An ATX SMPS transformer can drive an ultrasonic transducer

4) I've ordered parts from DigiKey

5) My ears hurt, and I don't know why...

ATX supply makes a good DC supply

I'm using a discarded ATX supply as the DC supply for the ultrasonic driver board. With 12 volts at 15 amps, the system can supply 180 watts of drive power to the transducer circuit. The biggest transducer I can find on eBay is 120 watts, so the range is good.

I mounted the supply on a board with decent bus connections and a current monitor tap. Harbor Freight was giving out free DVMs at one point, so I got a bunch and use them as embedded current/voltage monitors. The system is pushing 5.23 amps in the image below.

The new driver board works

The driver board, which uses an SMPS transformer scavenged from a different ATX supply, works. The transformer generates enough voltage to drive quite a bit of power through the transducer at resonance - I've had the system "accidentally" up to 17 amps, which is 200 watts, or double the rated transducer output.

It's a bit noisy, so I have to figure out some way of filtering. Also, I have to add some circuit protections such as zeners on the driver gates and such. Maybe a bypass cap on the gates as well.

The power driver is the perfboard sitting in front of the current meter (yellow-stripe transformer).

SMPS is working, manually

The SMPS circuit is working manually; meaning, I can adjust the frequency and duty cycle using two pots. I'm waiting on some parts from DigiKey, then I'll be able to hook the system up to an Arduino to monitor and control frequency and power.

My ears are still ringing

While attempting to get a picture of the system pushing 10 amps (120 watts), the system accidentally ran up to 17 amps for a few moments.

Despite immediately shutting down the system, the transducer managed to walk across the table (no mean feat at 28kHz) and my head has been ringing ever since. And I never heard a thing.

Yikes!

I suppose this is the ultrasonic version of playing with lasers, I'll have to come up with some type of safety gear to protect myself. Maybe earplugs?

Have to do some research...