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 #260 – How do you test usb to serial converters? (CP2103 vs CH340E vs FT232RL)

Welcome to a new Voltlog, today we’re comparing a few different serial to usb adapters and the discussion started ever since I showed the CH340E breakout board I designed in voltlog #249. People wanted to know if this CH340E affordable chip would perform similar to the well known FTDI or Silicon labs chips, and I’m thinking at high throughput and reliability here, the kind of application where you are sending lots of data, fast and you need it to be transferred reliably.

So today I’m going to compare the CH340E with a CP2103, and the FT232RL. I wasn’t sure what measurements to take and how to test these but I devised 2 testing methods.

Voltlog #230 – Guidelines For Board Level Temperature Sensor Layout & Placement

Welcome to a new Voltlog, today I’m gonna show you some techniques that you can use when doing temperature measurements. Typically you will want to measure either the ambient temperature or the system or component temperature. Depending on one of these goals you are going to follow different design rules to achieve that. And to better illustrate the problems, I have these 3 pcbs which have exactly the same electrical circuit but with different layouts on the pcb.

The boards consist of an esp8266 and a digital temperature sensor and you might expect that since all 3 boards are placed so close together, they should all indicate the same temperature but that is not the case as we can see on this graph we are getting 3 different temperatures and only one of them is close to the actual ambient temperature measured with another thermometer, so why is that happening? Well the answer lies in the layout of the PCB and that includes component placement, copper planes and various other elements on the PCB.

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 #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.