ozarkshermit
New Member
Howdy:
I am attempting to build an ultrasonic "Dog Chaser" using a classic push-pull driver (circuit attached), and a cheap Piezo Tweeter. I use a PIC to output varying frequencies of 15 - 17 - 21 - 23 - 25 - 27 - 30 and 33 KHz, in two and 1/2 second bursts, then repeating. The output from the driver is definitely functioning, changing frequencies as it should. (I can see the proper frequency output on a Scope) The thing is - I can hear something at all of the different frequencies, which seems to tell me that the tweeter is not oscillating at the driven frequency.. with these old ears I would doubt that I would hear even 15KHz.
The speaker is connected as shown, using 9 volts (not 12 as shown) across the driver. The PIC outputs (which are out of phase to each other) are connected to the 1K resistors feeding the transistor bases. The PIC shares a common ground with the driver.
The Tweeter has the specs shown below:
*Similar to KSN1016 *Power handling: 50 watts RMS/75 watts max *Frequency response: 3,500-27,000 Hz *SPL: 94 dB *Dimensions: A: 5-3/4", B: 2-3/4", C: 2".
I realize the top frequency response shows 27 Khz, but the lower ones should be OK.
Should I be applying a higher voltage to the tweeter so as to drive it harder? Or is there something simply stupid with my approach?
Thanks
Ken
I am attempting to build an ultrasonic "Dog Chaser" using a classic push-pull driver (circuit attached), and a cheap Piezo Tweeter. I use a PIC to output varying frequencies of 15 - 17 - 21 - 23 - 25 - 27 - 30 and 33 KHz, in two and 1/2 second bursts, then repeating. The output from the driver is definitely functioning, changing frequencies as it should. (I can see the proper frequency output on a Scope) The thing is - I can hear something at all of the different frequencies, which seems to tell me that the tweeter is not oscillating at the driven frequency.. with these old ears I would doubt that I would hear even 15KHz.
The speaker is connected as shown, using 9 volts (not 12 as shown) across the driver. The PIC outputs (which are out of phase to each other) are connected to the 1K resistors feeding the transistor bases. The PIC shares a common ground with the driver.
The Tweeter has the specs shown below:
*Similar to KSN1016 *Power handling: 50 watts RMS/75 watts max *Frequency response: 3,500-27,000 Hz *SPL: 94 dB *Dimensions: A: 5-3/4", B: 2-3/4", C: 2".
I realize the top frequency response shows 27 Khz, but the lower ones should be OK.
Should I be applying a higher voltage to the tweeter so as to drive it harder? Or is there something simply stupid with my approach?
Thanks
Ken