Anyone have experience to interface with a 200kHz depth transducer through the RCA cable? So far, i had searched some of ultrasonic transmitter and receiver circuits. However, i required an ultrasonic transceiver circuit in order to interface with the depth transducer. Besides, i had used timer 555 and LM393 to generate the pulses, but i dont know how to combine it with the receiver side so that it could act like a transceiver. Thank you very much!
Hello Bing, I just had a look at the circuit diagram of a small echo sounder LX200 by Datamarine.
The output transformer has a primary winding with the power transistors. Two secondary windings are used. One winding to the transducer. One winding to a 15K resistor and two back to back diodes 1N4148 to the common/ 0 volts/ gnd. The receiver input is across the two diodes. The other side of this winding to common/0V/gnd.
When the transmitter operates, the receiver input only gets hit with a couple of volts at most, protected by the two diodes. In receive mode the 15K resistor will attenuate the incoming signal to the receiver. Just have to live with that little bit of loss. The incoming received signal will be in the 10s of microvolts or millivolts range. The diodes have negligible affect on the received signal.
Hope that helps a little.
Regards, John Crighton Sydney
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