Friday, 13 November 2020

ESP32 Simple Wifi server

I am exploring the Wifi possibilities of the ESP32 module. 

I found a sketch that enables you to switch on/off a LED via the module through an internet browser. I selected pin 2 as output, since this pin is connected to the internal blue LED of the module.

The LEDs on the ESP32 DEV module

The sketch includes the 'wifi.h' subroutine that sets up a steady wifi link to your local network.

I adapted the sketch and included two counters that shows you the number of switch on/off actions in your browser.

So now I have two-direction data traffic from the ESP32 mini wifi server to the internet browser. It works fine.

Part of the sketch:

This is how it looks like in the browser:

I am impressed by the Wifi capabilities of the small 3$ device.

Update 21 Nov 2020;

I added this Wifi functionality to the CO2 analyser (see also blog 4 Nov 2020).

Wednesday, 4 November 2020

ESP32 lessons

Past days I learned a lot about the ESP32 microcontroller. Internet taught me how to connect an LCD to the controller and how to read analog inputs.

I installed the Arduino IDE with the Espressif files to be able to program the ESP32 development kit in "C".

At this moment I have a working prototype of a CO2 sensor circuit. I used an MG-812, CO2 sensor.

This is how the setup looks now:

CO2 sensor setup

The circuit consists of an analogue and digital part:

CO2 sensor analogue circuit with 10x gain opamp

CO2 sensor digital circuit

This is my first program in "C":

It was an interesting voyage to get the module in action. Lots of features are there to be discovered; wifi and bluetooth function, I2C protocol, PWM outputs etc.


-The electrolytic capacitor of 10 uF between EN and GND on the ESP32 module was necessary to upload the program to the module. It took me a couple of days to find that out.

-The max input voltage of the ADC inputs is 3.3 V. That's why I installed a 3V3 zenerdiode after the output of the opamp.

Update 21 Nov 2020:

I added the wifi functionality to the software. I can read out the CO2 concentration via the internet:

Also placed the ESP32 module onto the board:

Sunday, 25 October 2020

Internet of Things

I read some interesting stories about the IoT lately. The ESP32 development board turns out to be good starting point to do some experiments with Wifi, Bluetooth etc.

I ordered a couple of this interesting, low priced, devices.

Time to get familiair with the Arduino IDE and the C programming language.

Off topic:

Krammerdam, 8-nov-2020

Saturday, 17 October 2020

73 from St. Petersburg

Last wednesday, I made some HF FT-8 contacts. The QSO with Sergey, R1AV was one of them:

Off topic:

Outer port Zierikzee

Wednesday, 23 September 2020

Magnetic Loop Antenna Controller

With Gerard, PA2G I am working on a magnetic loop antenna.

I have started with the Magnetic Loop Controller. The design of the controller is from Loftur, TF3LJ / VE2LJX.

Frederik, ON5AI provides nice DIY-kits for this design

The hart of the circuit is a Teensy3.2 controller. I am using a steppermotor 17HS4401, which will drive the Vacuum-C of the antenna configuration.

There will be some interesting challenges: housing of the SWR-pcb, housing of the controller, interface with the HF radio, etc.

Magnetic Loop Antenna Controller

4 x 20 character display

Status Oct. 4, 2020:

Thursday, 17 September 2020

Casedemic, data against hysteria

 If you are interested in the science, statistics, graphs and numbers describing Covid-19, this video presentation of Ivor Cummins may be interesting for you:

His message: Be aware of Casedemic Hysteria

Update 14-Nov-2020:

There is a second bump this autumn in The Netherlands, but not a second 'wave' as often stated by the mainstream media.

Sunday, 6 September 2020

PI7CIS beacon

PI7CIS is a 2 meter / 70 cm beacon with QTH locator JO22dc (Scheveningen). The distance to my QTH is appr. 60 km.


It transmits CW signals on 144.416 MHz (45 W) and 432.416 MHz (75 W). Antenna height is 42 meters ASL. More info:

I was looking for a steady 70 cm signal for experimenting and improving the stability of my 28 - 432 MHz transverter and found PI7CIS. I am trying to improve the transverter's 404 MHz oscillator stability. This oscillator is not temperature compensated (TCXO or OCXO). With a small resistor-heated heatsink on top of the oscillator I try to improve the short term stablity.

                                                70 cm beacon on screen

Monday, 24 August 2020

Audio-video website

I added a new website to 'nice web links'. It was recently launched by my son Johnno. He is an audio-video equipment product specialist.

Visit his website (Dutch only) here:

Thursday, 20 August 2020

144 MHz FT-8 activity

Yesterday, I noticed good FT-8 activity around 144.176 MHz.

I used my logper antenna and picked up signals from UK, ON, F and D.

Off topic:
Just beautiful:

Sunday, 19 July 2020

Fieldstrength meter

I replaced an insensitive VU meter by a 100 uA meter on my fieldstrength meter:

This meter uses a quadrupler circuit to increase sensitivity:

The Ge-diodes (OA85) make the meter useable even above 500 MHz.

Off topic:

Tholen, 8 Nov 2020