Voltlog #289 – 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 remind 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. 

I must say I’m noticing delays in delivery of these packages from China, it started with orders placed mid January and I’m probably going to see some packages lost and never delivered so i recommend you keep an eye on your orders and request a refund when the protection time expires.

Voltlog #285 – Is a Cheap Cordless Power Drill Any Good?

Is a cheap cordless power drill any good? That is a question I’ve been asking myself for a while now because I was in the market for a cordless power drill. I can get a well known brand like Makita which sells a kit with two 18V 3Ah batteries, the drill and a charger for about $200. The thing is I’m using a tool like this maybe once every 3-4 months for a couple of drills, generally soft materials or maybe to assemble some new piece of furniture and I don’t feel like spending $200 for a tool that’s not going to be used and worked for that money.

So I started looking at alternatives, there are the clones of Makitas and Dewalts available for probably less than half the price of the genuine stuff but why go that route? I don’t care about what’s written on the label and the color of the drill.  One thing I care about is the shipping of the item, preferably I would like something that can be ordered and shipped from the EU for fast delivery and no additional taxes being paid for customs.

So I started looking at Chinese brands, this particular model got my attention on banggood.com, they call this a 36V cordless drill, it comes with two batteries and it’s available from a warehouse in the EU.

Voltlog #282 – Did I get a trinocular microscope for micro-soldering and inspection?

Welcome to a new Voltlog, to save you from waiting, the short answer is yes, I did get a microscope for the lab but before I show you the microscope let’s talk about why I got a microscope and why you might want one. If you are occasionally soldering boards, electronic kits, mostly through hole components or even surface mount down to 0603 and you have good eyesight, then chances are, you don’t need such a microscope, I’ve been doing that for years.

On the other hand, if you want to be able to solder surface mount components smaller than 0603 comfortably or you want to do board level repairs on modern gadgets like smartphones and laptops, then you most definitely need a microscope as it will massively improve the quality of your soldering and the general repair process at your bench. 

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 #241 – The World’s Cheapest Digital Watch (Teardown)

The only thing that seemed interesting when I first saw this was the price which was $0.90 delivered. I could not believe that you can get a wrist watch for 90 cents delivered from China and yet it’s true and there are still models that sell for under $1 dollar.

Voltlog #229 – What’s The Smallest Digital RGB LED?

Welcome to a new voltlog, today we’re talking about RGB LEDs. Everyone knows and probably uses digital RGB LEDs these days because they’re convenient, you only need a single pin to control then, they can be chained one after the other creating long addressable RGB strings, you don’t have to worry about driving them with constant current, in fact they even have digitally controlled brightness settings so they’re pretty convenient.

Since these are digital, they have a built-in controller chip, and if we take a closer look at one of these LEDs which comes in a 5050 package, we can see the driver chip and the 3 LEDs red, green blue with their corresponding bonding wires. There are two popular drivers chips the WS2812 and the SK6812 and each of these might have different revisions as well. The WS2812 was the original one on the market and then the SK6812 appeared and is considered a clone of the WS2812 but brings some improvements. The SK6812 has doubled the pwm frequency at which it drives the LEDs which is always welcomed as it helps with reducing flicker and also the timing requirements are a bit tighter but existing WS2812 libraries should work fine with the SK6812.

Voltlog #217 – Constant Current LED Driver Boards Assembly & Testing

Welcome to a new voltlog, today we’re going to assemble some prototype PCBs for different constant current LED Drivers. I’ve designed and ordered these pcb’s a while ago, the goal is to test different constant current led drivers I have ones that are switch mode and ones that are linear and I wanted to see if I can get away with using the linear ones, because there is a significantly lower part count at the expense of burning energy away and generating more heat.

I haven’t ordered a steel stencil for these pcbs, I’m gonna hand assemble them, I’m gonna use some of this mechanic leaded solder paste which comes in a syringe and then I’m gonna reflow the boards over a hot plate. One hint here about the paste, if the syringe is very old, the paste might get dry which will make it unsuitable for the job and not to mention hard to push out of the syringe so try to keep the paste fresh by storing it in a fridge and replacing it when it starts to dry up or separate inside the syringe.

These two boards will be powered from 12V current through LEDs will be 25 mA and the total string voltage is 10 V calculated with a typical led forward voltage of 2V. That means the difference of voltage will be dissipated on our regulator and that can be calculated 12V-10V we have 2V dropping on the regulator times our current 25mA and is equal to 50 mW.

Voltlog #213 – 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 the video with a battery charger from Liitokala, model number is Engineer Lii-500. It works with an external 12V power supply which I opted not to get because we all have a bunch of 12V adapter from old equipment.

Voltlog #203 – InTheMail With Cheap Electronic Components

So LCSC seem to be trying to be like the Digikey or Farnell of china and I think they are succeeding. Yes they have many problems regarding their website, which doesn’t exactly make it easy for us to filter and find the required part as we will see in a moment, but it might be worth the trouble because you get access to a whole new set of chips coming from Asia that you wouldn’t normally find and all of this at very affordable prices.

Another advantage is that you can bundle together your PCB order with your Component order and have them delivered in the same package. That’s a pretty neat idea, considering that you find anything you could need in their inventory. You could practically build an entire project with just a single order placed online.

Voltlog #197 – Wiring LEDs Correctly Series vs Parallel

Welcome to a new Voltlog, today we’re talking about LEDs, light emitting diodes and how we can connect them if we have multiple units. This is one lesson I wish I knew from the start because back when I started tinkering with electronic circuits I built a few projects with LEDs which let’s say could have been made better if I knew the stuff I’m gonna present in this video.

So let’s start by giving you a short story about this project I built back in 2010 so, 10 years ago I saw this project made by Ladyada, I believe back then Adafruit was just starting, they were selling just a few kits. The project was called tv-b-gone and it was a small microcontroller with an IR emitting diode, and it contained power off codes for most available tvs. The purpose was to point it at a TV, upon activation it will cycle all the codes and eventually the TV would turn off. Obviously a fun project that could potentially torment those around us.

So I decided to use a bunch of IR LEDs to increase the power of this circuit. And this is where I made the mistake of having all LEDs in parallel each with its own current limiting resistor. This meant I had to drill and install a bunch of different resistors and due to variations in the resistor value, the leds were running at slightly different currents, outputting slightly different power levels.

If I were to redo the circuit today I would probably connect them in series and use a boost circuit to drive the series string with constant current.