Voltlog #276 – What Is The CO2 Concentration In Your Home?

Welcome to a new Voltlog, in the previous video I showed how I built this monitoring system for CO2, it’s based on an ESP32 development board and it uses two sensors the MH-Z19B and the CCS811. In that video I explained the differences between these two sensors so please watch that to better understand the current video and the conclusions presented here.

I’ve let the system run and collect data for the past few days and now we can take a look at the data and draw some conclusions which might help you decide what sensor to use in your future projects or it might determine you to build a similar data logger to check the CO2 levels in your home because I assure you if you do not have a ventilation system, chances are you are sleeping in some high CO2 concentration levels.

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 #266 – How To Check If Your Raspberry Pi 4 Is Throttling CPU

Welcome to a new Voltlog, today my raspberry pi 4 is again in the spotlight because I want to show you the different scenarios where the board could be throttling down the CPU frequency and how you can identify those. Because it might be a case where your raspberry pi is running slow on a particular task and you don’t know why because there is no built-in mechanism to let you know when the board is throttling down. There are logs which you can check but let’s be honest, few people actually check the logs for something like this.

Throttling of the cpu frequency occurs for good reasons, to protect the board or the cpu from overheating or to prevent any errors from occurring in the case of an under-voltage scenario which may lead to data loss or corruption. Luckily there is a way to check if your system is under one of these conditions, you can run this command on your raspberry pi.

Voltlog #264 – Passive Heatsink Cooling For The Raspberry Pi 4

Welcome to a new Voltlog, here is my raspberry pi 4 which I got a few months ago when they released it and if you have one you might have noticed it gets quite hot especially when it has to do some processing. This newer processor, will get hot quick and the board alone cannot cope with all of this heat so what does it do? Well when the CPU temperature reaches 80 degrees Celsius it will start throttling down the CPU as a way of protecting itself from overheating and this will result in a loss of performance.

The Raspberry Pi 4 has a 1.5GHz quad-core 64-bit Arm Cortex-A72 CPU, that’s roughly three times the performance of the raspberry pi 3 cpu. That inevitably generates more heat. In the original plastic case just sitting idle, connected to a network, doing pretty much nothing, the raspberry pi4 when compared to a raspberry pi3 runs about 12 degrees hotter.

Voltlog #261 – InTheMail

Welcome to a new InTheMail, the series that will touch both your passion for electronics and your bank account at the same time.

Voltlog #216 – InTheMail

Welcome to a new voltlog, the series that will touch both your passion for electronics and your bank account at the same time.

We’re gonna start with this multimeter thermocouple which I got from ebay, it’s brown, it looks familiar to those who have a fluke multimeter, and yes it’s branded Fluke. However I got this from ebay for just a few dollars delivered from China so it might as well be fake but honestly who cares, it’s just a thermocouple, it’s gonna work just fine even if it’s a fake one. The think is I got my fluke 87 used without original packaging so it was missing the thermocouple but now I can plug this in and measure temperature as well.

Voltlog #195 – Is Thermal Adhesive Tape Any Good?

Welcome to a new voltlog, today we’re gonna be testing and comparing thermally conductive double sided tape to other solutions like thermally conductive adhesive, silicone pads, or even regular double sided tape to see how effective these solutions are for transferring heat between an IC and the heatsink.

To produce the heat I’m gonna use a small analog electronic load circuit, which will be set for a certain current let’s say 200mA and in theory should produce the same amount of heat for each run. Then we’re going to insert the different type of materials between the heatsink and the IC and we’re gonna measure the temperature of the IC and the temperature of the heatsink. As you can see I have a thermocouple glued to one side of the heatsink with thermally conductive adhesive and another thermocouple glued to this TO247 style transistor that’s producing the heat.

I don’t have a particularly good way of testing this but my plan is to heat the transistor to a stable temperature while the heatsink is kept at room temperature. Then I’m gonna connect the two bodies and measure the time it takes for the heatsink to reach the same temperature or a certain value, close enough. Then repeat the test with a different material and compare the values. If that time span is shorter or longer will depend on the thermal resistance between the body of the transistor and the heatsink and that is highly dependent on the material used between them.

Voltlog #172 – InTheMail

Welcome to a new InTheMail the series that will touch both your passion for electronics and your bank account at the same time.

Here are links to all the products shown in this video:


VolLog #129 – Ebay Bussmann Fuse vs Genuine Bussmann Fuses DMM-B-44/100-R

If you remember Voltlog #117 in that video we analysed some ebay Bussmann fuses to try and figure out if they are fake or real fuses. The ebay fuses we’re way cheaper than anywhere else so that made me suspect they are not genuine.

It’s good to know if the ebay fuses are real or not because they are selling allot of them and people might be relying on these to perform as required when in fact they might be out of spec. For the average bench user which only occasionally goes up to 240VAC it might not be an issue if the fuse is slightly outside the specs but if you are probing some high energy circuit and relying on the ebay fuse to perform according to the datasheet at it is not then something serious might happen, like the multimeter could explode because of a high energy discharge or it could simply damage the meter which is to be avoided.

Links for the products and test equipment shown in this video:


Voltlog #122 – C5W LED vs Incandescent Bulb Temperature

Welcome to a new voltlog, in a previous video I showed these C5W LED bulbs that I got from ebay they were very cheap so I put them to a test and discovered they reached very high temperature in just 15 mins of running in free air which got me concerned, the fixture of this bulb could melt.

C5W LED Bulb on Ebay 

C5W LED Bulb on Aliexpress 

C5W LED Bulb on Banggood 

Thermometer used in this video