Re: Ultrasonic Transmitter questions

On Fri, 16 Dec 2005 07:46:49 GMT, (Rubicon) wrote:

>
>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.
>http://www.geocities.com/talionis.geo/Temp/temp.html
>
>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.

---
If your receiver is getting swamped because of too much power from
your transmitter, then you'll have to learn how to AGC the RX. Or,
alternatively, couple a transmitter to the receiver and a receiver
to the transmitter so that if the receiver gets overwhelmed it will
tell the transmitter to stop shouting. But make sure that the
receiver doesn't also shout, or else neither one of them will be
able to understand the other.

--
John Fields
Professional Circuit Designer
.

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