I am looking to construct an MCU based ultrasonic fish finder. I have found a potential component that is a transducer called the TD02002 which can be found here:


Unfortunately, try as I might, I haven't found any data sheets on how it might be used


It has a phono type plug on its cabling. I am at a loss on how to drive it. Does anyone have any source materials or circuits for building fish finders? Ive performed an evenings worth of Google searches but come up dry.

Update: The supplier sent me a datasheet ... but I am still lost on how to drive it:



1 Answer 1


I haven't done any fish finders, I've played with ultra sonics. (I don't know what frequency they use for fish finders, but maybe one of the manufactures spec sheet will tell you.)
Anyway, you want to first hit it with a big voltage pulse. Maybe one or two cycles at it's resonant frequency. (most new signal generators will have a burst mode that you can use.) This sends out a sound pulse in the water. Then you are going to use the same transducer as a detector... looking for the reflected wave. An opamp will probably help here, but to start you should be able to just plug it into a 'scope input. Now you've got to do some math... look up the speed of sound in water. Figure out how long it will take for the pulse to bounce off something and come back. You want this time to be much longer than the burst that made the sound pulse... 'cause your transducer (and any amp) has to recover from the large drive signal. I'm not sure a bucket will be deep enough. Maybe you can launch the wave's horizontally in a bath tub and put a board down into the water to reflect the wave.

  • \$\begingroup\$ Thanks George. I live in Texas and am fortunate enough to have a swimming pool in my yard. I wrote to the supplier looking for a data sheet which I have now attached to the original post. I'm afraid I'm a hobbyist rather than a professional EE so I'm afraid that I would need some hand-holding. When we say a "Big Voltage Pulse" ... that leaves me with questions like "How Many Volts and for how long?". \$\endgroup\$
    – Kolban
    Commented Jun 17, 2015 at 14:17
  • \$\begingroup\$ Do you have a function generator and 'scope? I was using a higher frequency transducer. (1-4 MHz.) For which I could drive it with only the function generator (at max amplitude.) 20 Vp-p. The time was one or two cycles... for 200kHz that is 5 or 10 us. You'll have to turn up the gain on the 'scope.. I hope this will get you started... (but no guarantees.) Bouncing off the bottom of a swimming pool should work. Once you can see a signal you can work on making it bigger. Higher voltage pulse will give more reflected signal... and then a preamp. \$\endgroup\$ Commented Jun 17, 2015 at 14:35
  • \$\begingroup\$ Thanks again George. Unfortunately I have not yet invested in a function generator nor a scope ... my tinkering has so far been on breadboards with Arduinos and following pre-built schematics ... I may be at the limit of my capabilities. What I think I will have to do is back-off this question and study a ton more and then invest in a scope and come back to this project further down the line. Thankfully ... I do understand the principles you state, just don't yet have the skills or equipment to execute. \$\endgroup\$
    – Kolban
    Commented Jun 17, 2015 at 14:39
  • \$\begingroup\$ No problem Kolban, (I'll delete this comment soon or we get yelled at for chatting.) I don't think I could do electronics w/o a 'scope, func. gen. and power supplies. You could probably hit the transducer with a pulse, width ~2.5 us (1/2 of the 200 kHz period.) But seeing the reflection will be hard. Are there any hacker spaces in your area? Someone there might be able to help. \$\endgroup\$ Commented Jun 17, 2015 at 15:33

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