Some ultrasonic transducers have voltage maximums. You might want to find out if the one you are using has a maximum, and arrange to limit the voltage below that maximum.
Also, are you connecting the high side to 5V when output is 'off'? Is this the same supply that you are using to power the logic chips? I haven't spent much time looking at the circuit, but it is possible that there could be some issues with noisy supply lines when the inductor is switched to that rail.
Hello,
Quite awile ago I started a project to make an as powerful I can get ultrasonic remote control with TX and RX circuits capable of sending and receiving serial data. I've been at it off and on and so far I have it working as far as the TX circuit sending a single byte with a qualifier byte over and over until the receiver circuit detects it and acts upon it.
The latest TX circuit involves an upgrade of PIC from the 16F84A to the 16F628A, change of code, elimination of a 40kHz 555 timer circuit and transducer drive transistor with the addition of a relay, R/C filter, AND gate, mosfet and an inductor.
As a rank newbe I hope you could spend a little time to take a look at a partial schematic of the TX circuit and let me know what I've done wrong or how I could improve upon it.
The main 13.8VDC power supply is 16V "zenered" and well filtered while the 5VDC is regulated. The relay is because I have no automatic gain on the RX circuit (don't know how) and it gets swamped if the TX is too close.
Cheers,
Andrew.
Sorry for the late thankyou for your replies.
Cheers,
Andrew.
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