Interfacing fish finder take 2

The JSN-SR04T don't work underwater and it is not the same frequency compare to the lucky fishfinder so we cannot switch the transducers.
If your project can work with a open case lucky finder, I can help you make it work by guiding you cutting specific trace on the pcb and then tapping the signal to an arduino. It work very well and I was able to improve the short distance sensitivity from 0.9m to less (value somewhere in previous posts) since I d'ont care about fish finding or echo shape. Unfortunately a open gut lucky finder don't suit my need. So this is still a standby project in my case. I ordered some transducers but have'nt find time to test them yet.
For this to work, you need a Mosfet like this :FQP30N06L or hack the onboard triggering transistor array. Both work and the latter might be easier.


okay I'll try your advice. while im trying to find out where I can get these mosfet cause it is super hard to find electrical component in my area, I want to know if we can make the arduino release 200Khz PWM signal, can we make it work? and if it need 190v of 200khz signal is there is any way we can increase the voltage to the minimum working voltage? and use op amp for the returning echo? thank you for your reply it was very helpful. im sorry for my bad english.

1- I build me test system on ESP32. It will probably work on Arduino.
2- You don't really need the mosfet. You can hack the onboard electronics.
3- what you do need and that I forgot is a opamp and the components to reproduce the schematic in post #48 but be aware that the setup work but Jremington recommend other more suitable opamps than MCP6002. You may have more choice with Arduino since it work on 5 volts instead of 3.3v like my esp32.

hey i just want to give some update. I've tried to use AJ-SR04M as the driver for fish finder transducer and its work with pretty decent result

I know it have diffirent frequency but it still work. I think if we can make 200KHz with just same voltage level as AJ-SR04M it will work fine. I've tried the fish finder (not Aj-SR04M) too in deep ocean and it have about 40 m depth reading limit.

next week ill try with more accurate measurement. even tho that AJ-SR04M has 6.5 m limit and since sound move about 4.411 faster in the water so the limit also increase to about 20..m or so. and that enough for my project. I'll keep up next week.

AVR340: Direct Driving of LCD Using General Purpose IO

Many products require a Liquid Crystal Display (LCD) Interfaced to a
microcontroller (MCU). This application note describes the operation of a
Multiplexed LCD. Also discussed are electrical waveforms and connections
needed by an LCD, as well as a C-program to operate the LCD. The result is an
excellent low-cost combination and a starting point for many products.

Although multiplexed LCDs are initially more complex to get operational, they are
the lowest cost displays and requires the lowest number of I/O pins of all glass
LCDs (glass refers to the lack of an additional onboard LCD driver chip).

Today, I found this great manual, which implies the picture on the display can be quite rich.

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