Hi Peter, I'm trying and I can't measure underwater, I changed the speed of sound to water in the code and it doesn't work for me, could it be because I'm testing in a pool? If it's not a bother, could you help me with the code you used?

@@miltondacilva6401 hi milton,you have the same sensor? because there are more versions of the PCB board, can you provide your code

@@wolwerine777 If I have the same sensor, here I pass the code

@@wolwerine777 // Set the trigger pin LOW for 2uS digitalWrite(TRIGPIN, LOW); delayMicroseconds(2);//2 // Set the trigger pin HIGH for 20us to send pulse digitalWrite(TRIGPIN, HIGH); delayMicroseconds(20);//20 // Return the trigger pin to LOW digitalWrite(TRIGPIN, LOW); // Measure the width of the incoming pulse duration = pulseIn(ECHOPIN, HIGH); //distance = (duration / 2) * 0.0343; distance = (duration / 2) * 0.001435; // Print result to serial monitor Serial.print("distance: "); Serial.print(distance); Serial.println(" mm"); lcd.setCursor(0, 0); lcd.print("Distancia: "); lcd.print(distance); lcd.print(" cm"); delay(100); // Delay before repeating measurement delay(100);

Thank you!

I want to put it on an RC boat to map shallow water.

1. I haven't done more tests yet, but so far it seems to work. I am going to test another sensor as soon as I have more time that should be able to measure also shallower depths. 2. You could use an ESP32 instead of the arduino, so you would be able to transmit the data via wifi, and maybe even to control your robot remotely.

Hey Hoonish, I'm curious if you found a way to do that, I have similar idea too. Kindly let me know your status.

Thank you very much! I did use a plug with screw terminals and wires to make the connections. I'm sorry I dont have any schematics. I will try to add something in a future video when I figured out how to make it work.

@@Martin-ms4bu oh thanks for reply, can you give more details about the connections and the wiring pls, its a bit of emergency

Which connections are you looking for? I dont have that setup anymore. Everything is dissassemled again. But I can take a look at the wires in the video.

@@Martin-ms4bu And also it would be so much helpful if you can provide me with the code as well thanks a lot!

The code is super easy: You just pull the trigger pin high for a short time to trigger the sensor, then use int duration = pulseIn(echopin, HIGH) to get the duration of the echo pins signal. I did divide that duration by 2 and again by 6.7385 (for water) to get the distance in cm.

I don''t think this is possible with this sensor. As soon as it detects an incoming echo it changes the state of its echo pin. It doesn't listen for multiple echos. So the first echo it receives could also be coming from a fish, object or something else.

Hello! I'm sorry, but I haven't tested the maximum depth. I was more interested in the minimum values. It once worked in 3 m but I didn't try anything deeper than that. If you need the depth data in your setup and you already have a boat, would't it be possible to read the nmea / Seatalk data of your boats instruments?

Hi Henry, I think this kind of sensor wont't be able to do the job, because they are listening only for a short time after sending their pulse. If I understood correctly you are looking for a receiver to use on the bottom side to listen all the time for a signal from the surface emitter to trigger the release mechanism. Wouldn't it be possible to use a bouy connected to your instruments on the bottom with a line to retrieve them? I guess a sound based system would need a hydrophone which is constantly monitored for incoming signals. Maybe you can just use a normal microphone inside your waterproof container and send some loud ping or morse-code like signal with a speaker from the surface?

Hi Henry, If you've managed to pull this off Id be very interested in hearing from you as I am attempting to tackle the same problem myself. Kind regards, Alex

When I did my research I couldn't find one. But you can get those used fishfinders really cheap on ebay.

As far as I know it is not possible. Probably because the transducer works both as transmitter and receiver. I guess it needs some time to settle down after transmitting the sound before it can listen to it. I recently ordered some other sensors to do some testing. Maybe they will work better.

@@Martin-ms4bu so if i used two of this transducers i could measure smaller distances?

One for transmission and the other for reception

That might work. When you use 2 JSN-SR04T, you would have to send a ping with one, then shortly before it actually starts listening, send a ping with the second one. The first one may miss its own echo, but pick up the echo from the second transducer. EDIT: I actually tried it, but it didn't work. I guess the pulse returned by the module is at least 1100 us long. The datasheet says it is 150 us to 25 ms, but I can't read any shorter pulse.

I bought it online. The sensor seems to be around 7€ at the moment. I don't know if you can get it cheaper anywhere.

Sorry I dont have model and Brand at hand, but you can find them easily on ebay. They are relatively cheap.

@@Martin-ms4bu ok found with quimat keywor, thank you

Thank you! I have the board with the GPS and the SD card working now, but I didn't test it yet. I will upload a video with the results.

Hi, you just pull the trigger pin high for a short time to trigger the sensor, then use pulseIn(echopin, HIGH) to get the duration of the echo pins signal. I did divide that duration by 2 and again by 6.7385 (for water) to get the distance in cm.

@@Martin-ms4bu Hello Martin, I'm still trying to read the sensor, I followed your advice and I don't know if I'm wrong about something because I can't get it to work, I'll leave you my code to see if you can guide me, thank you very much in advance, you are a genius void loop() { long duration, distance_cm; digitalWrite(triggerPin, LOW); delayMicroseconds(2); digitalWrite(triggerPin, HIGH); delayMicroseconds(10); digitalWrite(triggerPin, LOW); duration = pulseIn(echoPin, HIGH); distance_cm = (duration / 2) / 6,7385; Serial.print("Distancia bajo el agua: "); Serial.print(distance_cm); Serial.println(" cm"); delay(100); }

@@miltondacilva6401 the code looks fine to me. Maybe try to read the sensor in bigger intervals. How far is the distance you want to measure? Do you get any reading at all? What values do you get for duration?

@@Martin-ms4bu Hello Martin, thank you for taking your time and guiding me, the idea is to measure from 2 meters of water onwards up to about 10 or 15 meters, I tested it in a bucket of water with 40cm of water and it is marked with a number 77 when I submerge it under water and I am applying a delay(500) . You will not have the code that worked for you in the test, thank you very much Martin and best regards

@@Martin-ms4bu My idea is to make a radio controlled boat to search for drowned people in the water.

I dont have a bathtub or a fishtank ;-)

@@Martin-ms4bu Next, you'll be saying you don't have a pot to test in.

I did those tests in deeper water, because I didn't expect those sensors to work in very shallow water.

I just ordered some new sensors that I want to test, but I didn't have the time yet. If I find one that works for shallow water, I will make a video of it.