Ultrasonic >100w amp for vibration exprmt...

So instead of working on the generator today.. I decided to play with that c300 that you linked too...

I tried feeding it with a variety of signals... but I'm getting out, almost exactly what I put into it...

...square wave is a bit distorted.. the sine looks great...

The input and output perfectly overlap on the scope...

Where is the gain???

Confused,
Michael

PS.. i swapped the mj15003/4 to mj15001/2 ... didnt have the spice model... and i used a 1n4752a for the 33v 1 watt zener...

Goldsphere~~

I was just re-reading the posts, this time with my eyes open~~

I was under the impression that Chladni plates needed a sine wave to reduce the other harmonics...

If I'm wrong, that would be great....

The plate... It's not exactly thin... (~310mm x 140mm x 18mm)... almost 2 cm thick aluminum...

And here is the FEA sim @ ~19,650 Hz ...

Michael

Well, I'm not sure about that. The frequencies are in the audible range though, at least for the less complex patterns. Here is a youtube clip of the effect.
https://www.youtube.com/watch?v=MPcJbb5Qfj0
It seems to me that a square wave would do the same that a sine wave would do in this circumstance because essentially you are just hitting the plate with a large compression wave. 18mm seems really thick to me, might dampen the wave a bit.

krazatchu said:

I decided to play with that c300 that you linked too...

I tried feeding it with a variety of signals... but I'm getting out, almost exactly what I put into it...

...square wave is a bit distorted.. the sine looks great...

The input and output perfectly overlap on the scope...

Where is the gain???

Click to expand...

The voltage gain is R14/R15= 10k/330= 30.3.
The spec's say that 1.2V RMS input gives 200W into 8 ohms output (40V RMS) but the input realy needs to be 1.32V RMS.

Audioguru.... thanks... something was wrong with those 2 caps c7 and c8.... took them out and now ~~I got gain~~
Now to figure out whats wrong with them...

Goldsphere.... I'll have to do some homework on that... I assumed that if I was driving extra harmonics the total power at the specific frequency would be lower... I'll find out and post my conclusions...

Michael

The caps were touching but not connected... silly oversight...

C7 and C8 are back-to-back electrolytics. Your simulator doesn't know about them. Remove one.