Voltlog #275 – CO2 Concentration Measurement System With MH-Z19B & CCS811

Welcome to a new Voltlog, you might remember these two sensors from a previous mailbag, this is the MH-Z19B and this is the CCS811 both of these report CO2 levels but they measure this differently and I’ll explain this in a moment. I got these two sensors in order to monitor CO2 levels in my home, to determine if the levels rise too much at night, especially during the winter time when we tend to keep the windows closed most of the time. I live in an old apartment building where there isn’t much provision for ventilation and so I suspect the air I breath during sleep is high in CO2 levels as it builds up over night.

In this video I’m gonna show you how I built the monitoring system using an ESP32 board that reads the sensor data and then sends it over the network to an MQTT server running on my raspberry pi. I then use node-red to insert the data into InfluxDB and then finally Grafana to monitor all of this data in a nice graphical user interface. The beauty of this setup is that all of this software is free to use and open-source.

Voltlog #273 – InTheMail

Welcome to a new InTheMail, the series that will touch both your passion for electronics and your bank account at the same time. Before I get started I’m gonna take a second to reminding you to subscribe to the channel and hit the bell notification icon because that’s the only way you will know for sure when I upload new videos. Now let’s start with this small esp32 based development board, it has a built-in 1.14 inch color tft lcd and I think that’s a nice feature of this dev board because if you want to connect some sensors and see the readings in real time, you don’t need to wire a display externally it’s built-in.

Another cool feature is that we have built-in battery charging at 500mA and you can power this board through the provided two pin jst connector with a one cell lipo battery which will then charge when connected to power via the USB Type-C port. There is also a CP2104 for the usb to serial conversion and that makes it a pretty well balanced development board for the ESP32.

The board comes loaded with a test program from TTGO, it shows this image then cycles through red, green, blue on the LCD which is a good idea because you can verify the board is functioning ok after the long journey it takes from the market in shenzhen to your door and we all know how well these packages are protected during shipping.

Voltlog #259 – InTheMail

Welcome to a new InTheMail, the series that will touch both your passion for electronics and your bank account at the same time. We’re going to start with this small white box, which looks very uninteresting from the outside but contains something really nice, it’s a machined aluminium heatsink, designed specifically for the raspberry pi 4 and inside the box you get the two halves of the heatsink plus some mounting screws and silicone thermal pads.

There is a decent amount of aluminium in this heatsink, and we can see it has these rectangular raised islands for contact with the main chips on the board, so this is where the silicone pads will go. This is a completely passive heatsink and that’s what I was looking for but if you want more cooling power these are also actively cooled heatsink. feel like I should test this in a separate video to see how efficient it is when compared to a no heatsink solution which we already know doesn’t work well with the raspberry pi as it gets pretty hot. So we’ll leave this for a future video.

Voltlog #257 – ESP32 PIR Motion Sensor With Deep Sleep & MQTT (revB part2)

In this video I’m gonna show the second revision of my esp32, battery powered PIR motion sensor. This second revision contains some optimizations to improve deep sleep power consumption as well as to fix some of the errors I had the first revision of the pcb.

Voltlog #240 – ESP32 PIR Motion Sensor With Deep Sleep & MQTT

Welcome to a new Voltlog, in this video I’m gonna show you how I designed and built this board which functions as an esp32 based, battery powered PIR motion sensor. So I started by designing the circuit, I used some common building blocks, I added the ESP32 with it’s bypass caps, some test points and the programming circuit with auto-reset, I then added some connection points for the PIR sensor, an RGB LED because why not have a nice way to signal this is one of those very small digital RGB leds, it’s just 20x20mm, it’s connected to 3.3V even though it’s only rated for 5V so I’m hoping this is going to work even on 3.3, it’s also worth having a temperature/humidity sensor to also sense that in whichever room the node will be placed and finally the power supply circuit which is a simple low dropout regulator with an 18650 battery as the input.

I did not include a battery charger circuit on this module, because I wanted to keep things simple, I’ll have a battery socket so I can just remove the 18650 cell and charge it separately plus the whole circuit should run in sleep for extended periods of time giving me a long operating time so i wouldn’t have to charge the battery too often.

Once the schematic was finished I did the board layout in a hurry so it’s not exactly pretty or optimized

but I tried to move the esp32 antenna to the side, to place the PIR sensor in the top side as the module will probably sit vertically, I tried to place the temperature sensor in the bottom side to keep it away from any components that might get hot and also placed some isolation slots for the same reason.

You should check-out revB of this board, I made some improvements present in the video below.

Voltlog #121 – InTheMail

This video starts with a rant about how bad the postal system is around here(Romania).

Here is a list with links to all the items shown in this video:

Voltlog #103 – InTheMail

Today we are taking a look at my electronics related mail, I’ve got a bunch of random stuff and links for all of them are provided below the video.

Voltlog #83 – InTheMail

Hello, and welcome to a new InTheMail. It’s been awhile since we’ve had one but don’t worry small packages from China continued to arrive, even through the holiday season and as a result I have plenty of new stuff to show on video.