ESP32 Metal detector

[ivconic]

Look at schematic TX capacitors are on IC7 pin 8

https://www.allaboutcircuits.com/too...ce-calculator/

Continual frequency change in wider range (as 6-20kHz is) with same capacitance will simply not do.
That's why i suggested you to define several sub-ranges and control them within code... along with some capacitor switching mechanism.
On XP Deus they used micro relays.
You can use bilateral switches for experimental purposes.

[Altra]

I finnally got it to compile and up load. As ivconic said window 7 uses different paths than win10.

This is what worked for me,

Win7 the Arduino IDE and support files are installed on C:\ Program Files(x86)\Arduino

The on-line instructions show this as being done in user documents\Arduino - will not work on win7

Then you need to create new folders under C:\ Program Files(x86)\Arduino\hardware\espressif\esp32
I manually downloaded the zip file from https://github.com/espressif/arduino-esp32.git. Unzip and place the contents into the esp32 folder

Now open tools in the esp32 folder and run "get" as administrator. It will download and unzip more files

Next down load "ESP_BLE_Arduino-master" from https://github.com/nkolban/ESP32_BLE_Arduino
unzip and place the folder in the library folder.

Under C:\Users\yourname\Documents\Arduino\libraries\ESP_ BLE_Arduino-master

I also left the folder ESP_BLE_Arduino that came from the library manager download. The esp32 metal detector sketch gave errors with only ESP_BLE_Arduino, once I added ESP_BLE_Arduino-master it compiled

Be sure select in the compiler "no-ota" under tools\partition scheme

[Marchel]

https://www.allaboutcircuits.com/too...ce-calculator/

Continual frequency change in wider range (as 6-20kHz is) with same capacitance will simply not do.
That's why i suggested you to define several sub-ranges and control them within code... along with some capacitor switching mechanism.
On XP Deus they used micro relays.
You can use bilateral switches for experimental purposes.

Yes I understand what you want to say in the next version of PCB can use the relay as it is in detector Deus.

[ivconic]

Yes I understand what you want to say in the next version of PCB can use the relay as it is in detector Deus.

You don't even need to design new pcb.
Just add another one with caps and switching mechanism.
Or... design new one as "multi-frequency" and keep the present one as "6-7kHz" version.
Yes you can use relays.

[CDI]

Anybody know if this can be powered with small Li-Po 3.7v battery?

[Marchel]

Anybody know if this can be powered with small Li-Po 3.7v battery?

7.4V Battery

[Altra]

Are you driving the MC34119 with a dac generated sinewave or just a square wave? Also I have attached a pdf file of the schematic

[Marchel]

Are you driving the MC34119 with a dac generated sinewave or just a square wave? Also I have attached a pdf file of the schematic

So far, it's just a square wave but pin 26 ESP32 is a DAC output so in the future there will be a sine wave just have to figure out how to do it .

[Altra]

A square wave is fine. You can actually eliminate the tx driver ic and replace it with a npn transistor or n-ch fet.

[moodz]

http://www.xtronical.com/testing-the-dacaudio-hardware/

The REALLY sad thing about the ESP32 is that they put in a 16 channel PWM system with duty cycle control BUT NO means to change Phase ( ie start stop times on each pulse ) except by messy interrupt hack .... DOH

[Marchel]

A square wave is fine. You can actually eliminate the tx driver ic and replace it with a npn transistor or n-ch fet.

Do you mean something like this ?

http://sevzirfo.narod.ru/mod03m.gif

[Marchel]

http://www.xtronical.com/testing-the-dacaudio-hardware/

The REALLY sad thing about the ESP32 is that they put in a 16 channel PWM system with duty cycle control BUT NO means to change Phase ( ie start stop times on each pulse ) except by messy interrupt hack .... DOH

Yes it is a problem

[Altra]

Do you mean something like this ?

http://sevzirfo.narod.ru/mod03m.gif

The mod03m.gif looks to be using a bipolar tx coil? On your coil this circuit will work. See attached drawing, you need to experiment with the series base resistor. I used a 15k. Adjust for a clean symmetrical sine wave. Also you should run that coil at 6.5khz for best performance. I noticed in your code somewhere it was 8Khz?

[Marchel]

The mod03m.gif looks to be using a bipolar tx coil? On your coil this circuit will work. See attached drawing, you need to experiment with the series base resistor. I used a 15k. Adjust for a clean symmetrical sine wave. Also you should run that coil at 6.5khz for best performance. I noticed in your code somewhere it was 8Khz?

Yes, I already know how to do it just like this, I will experiment with frequencies from 6 to 20Khz

[moodz]

Phased pulses on ESP32

... hmmm I was told by an 'expert' that we could not phase the pulses on the LED PWM controllers .... NOT TRUE.

bit of TLC and RTFM reveals we can generated pulses with no CPU overheads on upto 16 outputs with upto 4 clock references and 15 nanosecond resolution for Phase and Duty cycle.

Pix shows the result of Duty cycle = 10 clock periods, Phase offset by 1 count for 4 outputs on the "testbed" LOL

ESP32 PI controller lives