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Topic: A Sensitive DIY Ultrasonic Range Sensor (Read 12 times) previous topic - next topic

AlphaZeta

@cr0sh,

Thanks for those links!  I have to admit that building something from scratch does feel good regardless of the material cost.  ;)

Getting back to the one sensor question, The main challenge is to design a transmitter that is powerful and then at the same time to design a receiver that is sensitive.

In a one sensor design, the transmitter side usually is not bridged since the transducer needs to be multiplexed between sending and receiving. If the sender needs to be bridged the circuit will become even more complex.

Also a good analog switch chip that can deliver the power needed and has a low noise level is probably going to be expensive. But I think I might experiment with a single transducer design sometime just to see it myself.


AlphaZeta

Ran Talbott,

Yeah, I could have used some half-bridge/full-bridge chips to drive the transducer, but I don't have any lying around. On the other hand, I have hundreds of transistors right in my drawer :)...

retrolefty

#7
Jan 23, 2011, 06:37 pm Last Edit: Jan 23, 2011, 06:39 pm by retrolefty Reason: 1
Very nice, an experimenter's wet dream.  ;)

As a side note for possible improvement, I recall playing with an exterminators Ultrasonic kit that Polaroid sold in the early 80s. In their receiving circuit they added a AGC (automatic gain control) function to the op-amp stages. Seems the return echo amplitude decreases with distance, so their amp stages would start up with a lower gain and increase gain over time to better detect the received signal and have better signal to noise ratio overall. I'm sure this would increase distance capability but at some added circuitry complexity.

Lefty

AlphaZeta

Ah yes. I'll was thinking of trying out AGC, maybe it'll go into my version 2. Thanks for the suggestion retrolefty!

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