Making Kelvin Test Leads For My LCR Meter | Voltlog #326

A common mistake when building kelvin 4 wire test leads is to use standard alligator clips because in a standard clip the top and bottom jaw are electrically connected at the hinge point. This kinda defeats the purpose of having separate sense lines if they are getting shorted at some point with the current carrying trace. For a true kelvin connection you would need a special type of alligator clip, like the ones shown in this video, these have a plastic hinge and the top and bottom jaws are not electrically connected. These can be quite expensive if they are made by a good manufacturer but I got mine from aliexpress for cheap, they do not excel in quality but good enough for the type of instruments I am going to be using them with and with the amount of work volume they are going to see on my bench they will last a while.

Identifying & Replacing A Fake FTDI FT232R Chip | Voltlog #314

Lately I’ve been getting a few of these serial interfaces from aliexpress, this is just a RS232 to TTL level converter while this one is a USB to RS485 interface and it’s great that we can buy these for cheap for we are getting exactly that, something cheap. This converter chip is likely not of the best quality and not to mention this FT232 chip is certainly not a genuine one. 

There is nothing worse than having to deal with communication issues and debugging your tools instead of the actual project you are working on so I’ve decided to replace these chips with some genuine, good parts because the pcb and the rest of the circuit should be fine as long as we have a good conversion chip in there.

You might be wondering if there is any way to tell for sure that you’ve got an FTDI FT232R clone. There are at least 2 methods that I know you can use. First one is to install an older version of the driver which FTDI released in 2014, after plugging your fake FTDI depending on the driver version it will either disable the FT232 chip by writing something to it’s internal EEPROM or it will modify it so that it shows a custom alert message over serial instead of your actual data. I don’t like this method, because there is a better, simpler way, you can simply check for the serial number of the FT232 which you can get from the device manager under windows or by using the FT_Prog utility. If your serial number is A50285BI or 00000000 then you most certainly have a fake chip because that is a popular serial number which is written to fake chips. They don’t bother changing the serial number on the fakes, they mostly write the same number or set it to zero.

8W Rechargeable e-Cig Soldering Iron Review & Teardown | Voltlog #307

These days there is a wide choice of portable soldering iron and I think very few people still consider gas powered soldering irons who were quite popular 10-15 years ago because of their portability. 

Now you can get USB powered soldering irons like this one for about $6, it’s rated for 8W, takes a 5V USB input and you can plug this into any power bank and fix a solder joint remotely. I’ve used this a couple of times while doing some electrical work on a car and it was very convenient.

You can also get more powerful, more polished soldering iron like the TS100 which normally takes a DC input from a laptop power brick in the 20V range but since USB Type-C with Power Delivery is a popular thing these days, you can also power it from a power bank capable of at least 12V. But this will be in the $50-60 range and you need to purchase a special power delivery trigger cable separately.

However today’s video is not about these two options, I’m gonna show you something that fits in between these two. It’s delivered rather impressively in a cheap plastic bag but let’s see what we get in here. Looks like they included a small amount of solder wire, that’s nice, every soldering iron should come with a small amount of solder. We get one of these small foldable sheet stands so you won’t burn something when setting the iron on a surface. This looks like our soldering iron tip and inside here we must have the soldering iron body itself and a charging cable

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 #265 – FT232H USB to JTAG/I2C/SPI Interface With Python & PyFtdi

Welcome to a new voltlog, today we’re going to be talking about this little board which I designed and assembled myself, it’s a breakout module for the FTDI FT232H which is a usb to serial converter but with a nice twist. This particular chip from FTDI has the built-in Multi-Protocol Synchronous Serial Engine (MPSSE short) which allows you to run a variety of synchronous serial protocols like JTAG, I2C, SPI or simple bit-banging of IOs. You can imagine it can be really useful to be able to interface with a sensor over I2C or SPI straight from your computer over USB through this interface. You wouldn’t need an arduino or other controller in the middle if you plan to do some data acquisition for example.

Voltlog #262 – Is This The Future of Our Hobby?

To be honest I didn’t think we were going to have services like these available so cheap so fast. I mean yes I know pcb prices have been so low in the past couple of years that it no longer makes sense to etch your own PCBs, unless you are in a big hurry. But having smt assembly service so cheap? Soon enough it would not make sense to hand assemble these boards because it would be equally cheap to have them assembled at JLCPCB

Voltlog #258 – Cheaper Isopropyl Alcohol Wipes For PCB and Stencil Cleaning

Welcome to a new Voltlog, today we’ll have a little chat on IPA cleaning wipes. Professional PCB wipes soaked in IPA are pretty expensive and hard to get but can we substitute those with something cheaper that works just as nice for cleaning the flux residue from PCBs?

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 #256 – Best BST-863 Hot Air Rework Station (Alternative to Quick 861DW)

Inside the box of the BST-863 we have the station, a really nice and heavy stand for the tool piece, a total of 3 nozzles, a grounding strap and a power cord. The first thing I notice is the hose which pretty thick, certainly thicker than what I had on my old Gordak station but seems to be softer material. The way it’s designed with the tool standing vertically in the stand makes the air hose forms this loop which depending on your bench setup might or might not bother you but it’s something to consider. But I like the quality of the stand, it’s heavy and feels very sturdy, you get this accessory here which allows you to remove the nozzles while hot and the station has a sensor to detect when the handle is in the stand.

Adjustment of temperature and air level is made through this touch screen control. I’m a bit anti touch screen control on test gear so I would’ve preferred some switches on the front panel but don’t get me wrong, the touch screen works well on this unit, it has nice big touch keys and after setting up your presets you are likely  not going to need to adjust the temperature you will just be using the presets like leaded, lead free and another one for heatshrink maybe.

Is this cheaper station a good alternative to the Quick 861DW? This video review should provide you with enough info to decide which one to buy.

Here are some high resolution images from the teardown:

Voltlog #252 – How to fix a solder bridge

Welcome to a new Voltlog, today I want to talk about solder bridges and show you how to deal with them. A solder bridge can happen for many reasons, incorrect soldering temperature, incorrect amount of solder being used, too little or no flux, or just the incorrect technique for soldering but they all basically mean the same thing , a blob of solder shorting two or more conductive surfaces on your PCB.

Modern printed circuit boards which typically get soldermask coverage even between IC pins will help prevent this problem because molten solder normally doesn’t stick to the soldermask surface and so it’s harder to form a bridge across that surface.

But even with enough experience and the proper technique solder bridges can still happen if you do hand soldering on fine pitch ICs, it’s just part of the soldering job. It’s true that as you get better at soldering they will happen less often but don’t think they go away forever. So it’s good to know how to deal with them.