Review – Page 7

Voltlog #211 – Joulescope DC Energy Analyzer Review & Teardown

Welcome to a new voltlog, today I’m excited because we’re going to take a look at an awesome piece of instrumentation. I’ve received a pre-production demo unit of the Joulescope DC Energy Analyzer.

The joulescope is a low cost precision dc energy analyser which is currently on kickstarter so check the links in the description of the video for the kickstarter campaign because it has a massive discount from the retail price. The joulescope has circuitry for measuring voltage and current, from which it can calculate power and then it can integrate power over time to calculate energy. The current measurement range is from 10A al the way down to 1nA, that’s a huge dynamic range which makes it very useful if you plan to measure the energy consumption of a device that has mixed behavior for example an esp32 that will wake up, do some activity and then go back to deep sleep.

The joulescope works with a software companion that has a multimeter view and an oscilloscope view which I find very useful because it will allow you to time correlate measurements of voltage and current. That can be extremely useful when determining the energy usage of your device.

Voltlog #210 – 946C Hot Plate Review & Teardown

Welcome to a new Voltlog, today we’re gonna do a review and teardown of this hot plate which was supplied for free by banggood.com. So you would use something like this to preheat a pcb, to prepare it for desoldering an IC or even for reflow soldering a board. As usual there will be links placed in the description below which I encourage you to check out. There is a 100x100mm version at 400W and a 200x200mm version which I have here at 800W.

If you haven’t worked with a multi layer pcb you might ask yourself why do I need to pre-heat the board. Well modern devices uses a high number of internal pcb layers so desoldering something from those might be harder if you only heat the board from the top with hot air, it might take some time until the IC reaches desoldering temperature because the heat is sucked away by the internal copper layers.

This could be bad for the board and the IC because you will need to increase the temperature of your hot air station above the normal working temperature to compensate for that and in the process you might damage the board or the IC. Such a tool allows you to bring the board to a higher temperature without creating any hot spots, and then you can just heat with hot air from the top the are where you need to work.

Voltlog #206 – PCBWay Service Review

In this article I’m gonna review a set of PCBs I ordered from PCBway.com which I got for free for the purpose of this review. I have done several other PCB reviews in the past so if you would like to check those out, here are some links. (link, link)

In the article I’m only going to discuss the printed circuit boards themselves and the quality aspects of the boards. I will also be doing a short video on the subject where I will be discussing the ordering process and some aspects of their website.

So here is a picture with the boards I ordered, this is a simple breakout board I designed to interface to an epaper display.

It has all the bypass capacitors and additional circuitry needed to generate some voltages for the display. The SPI interface is broken out to header pins for easy connection to a controller board. The interface with the display is handled through a 24 pin, 0.5mm pitch flat flex connector.

How good is the soldermask?

So let’s go through some things that make-up a printed circuit board and analyze their quality. First let’s look at the soldermask, which in our case is green. This acts like a shield for the copper tracks, prevents oxidation and also helps during soldering if it’s present between adjacent pads.

The soldermask has opening for each connection pad and ideally you want the soldermask perfectly aligned so it doesn’t cover any area that you want clear. In the picture above (please excuse the low quality) we can see the soldermask aligns almost perfectly with the pad, no problems whatsoever.

How good is the silkscreen?

Next let’s talk about the silkscreen, which represents the legend of the PCB. In this case the silkscreen is white, which gives a good contrast over the green background created by the soldermask. The silkscreen contains valuable information like part numbers or values. In high density designs you want to be able to print small silkscreen and still be readable.

In the case of these boards I added different sized text on the back, and as you can see the text is clearly readable down to 0.5 text size in EagleCAD. I must say the quality of the silkscreen printing for these PCBs is excellent.

How are the drill holes aligned?

Another important aspect of a pcb are the drill holes and their alignment with corresponding pads. And here we need to take a look at the annular ring which is the circular area of a pad surrounding the drill hole. If you have a small via of just 0.2mm, the annular ring is very thin so it becomes very important for the drill to be exactly centered on the pad to avoid breaking the annular ring.

In the case of this design I specifically added a few rows of vias, starting from the left at 0.2mm, 0.3mm in the middle row and 0.4mm on the right row. This is so we can easily look at the quality and alignment of the drill holes.

In the close-up taken with my low quality microscope we can see the drill holes are well aligned with the center of the pad, on the 0.2mm vias and the 0.3mm ones, the holes are dead center with a perfect annular ring. We observer a slight deviation on the 0.4mm vias, which caused the annular ring to shrink on the left side of the pad but nothing to worry about, there is still plenty of copper in there.

There are also a few less important things that we need to take a look at because I might consider them less important but they might be important to you. For example, identification labels. This is something all prototype pcb houses will add to your pcb. This is a code, they will add in the silkscreen and print on your pcb so they can later identify your pcb among others placed on a larger pcb panel. Sometimes they will add this code under a large part, so it will be invisible in the finished assembled board, sometimes, they just place it in plane sight.

In the image above you can see how PCBway added that text under the connector, so once I solder that flat flex connector, the identification text is not visible any more.

Electrical test?

And the last thing I would like to mention is the electrical test of the board. That is normally done with a flying test lead machine, which literally has flying test probes, moving really fast, checking each pad and track for connection or shorts. That action will leave small scratch marks on each pad and that is usually a good indication that the test has been performed. However in the case of prototyping services, the electrical test is usually nor performed because it takes time, it’s expensive and the pcb’s are cheap.

Normally these prototyping services just have an AOI step in their production flow. AOI stands for automated optical inspection and with the help of high resolution cameras it can identify most problems by comparing the resulted pcb with the original design file. I think these pcb’s we’re not subjected to electrical test but just AOI instead.

And to conclude my review of their pcb service I can say the PCBs turned out great, they are of good quality, nothing bad to talk about here. Regarding their website and ordering process, I think they can do a few things to improve the customer experience.

I also did a youtube video, talking about these PCBs, if you would like to watch that, I’ll include it below.

Voltlog #198 – SUNKKO 737G Battery Spot Welding Machine Review & Teardown

Welcome to a new Voltlog, today a review video. So you know I’ve been talking about building my own spot welding machine in previous videos, that project is still active but progress is slow. In the meantime I’ve been contacted by banggood they wanted to offer something for review and I thought I’d try out a chinese spot welding machine, this way I could have something to compare with.

So I picked this model from their inventory the SUNKKO 737G, I got the 220V version for EU, if you live in a 110V country, you need to choose the appropriate model. If you’re interested checkout the links in the description below the video.

So why do we need a spot welding machine? Because it provide a safe & reliable way of connecting battery cells. Sure you could take the risk and try to solder your battery cells, I have done that in the past but I would rather avoid doing it if I can because it’s risky, the temperature of the cell will rise too much while heating it up with the soldering iron. This machine does it in the blink of an eye so the cell doesn’t get hot at all.

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 – Soldering tools & accessories

Soldering is probably the thing I do most often at the workbench and so it’s important for me to have a good soldering station. While a JBC station would be the perfect candidate they are super expensive and so out of reach for most hobbyists, that’s why I had to look for something else.

Hakko makes decent soldering stations, especially with their newer T12 cartridge style tips. But you can save even more by choosing an after-market T12 compatible STM32 based soldering station and buying just a genuine Hakko T12 tip from an authorized distributor. So here are references to the tools and supplies I use for soldering.

I use an STM32, Hakko t12 compatible, soldering station which I got a long time ago from Taobao. If you would like to see more details about this station you should watch Voltlog #85. Currently there are similar options available on Aliexpress or Ebay. Things to lookout or ask the seller about: does it have a soft and heat resistant silicone cable? Does it come with a stand, so you can rest the soldering iron? I would advise to get a couple of genuine hakko T12 tips from a known distributor.

If you get a hakko T12 compatible soldering station you will also need some T12 tips. As mentioned earlier don’t get them cheap from ebay, those are counterfeit tips that do not have the same performance as a genuine tip and this will directly affect how easy it is to solder something. I will list 3 of my favorite tip styles, but depending on the jobs you do these may or may not be the best choice: I use the T12-KU tip daily for almost anything, I use the T12-JL02 for fine smd work and I use the T12-D16 for thicker smd pads.

I sometimes use the hot air station, it’s either for repairs or quick assembly of surface mount components, and sometimes just for heating up heat shrink tubing. I have a very old one called Gordak 952 which is probably a clone of something from Hakko. It must be at least 10 years old but it still works and since I don’t use it everyday I never felt the need to replace it with something newer.

Currently there are better options on the market so take a look at these links on ebay and aliexpress for reference. If you will be using this a lot maybe you want something better, I’ve heard the Quick 861DW is a good hot air station: ebay and aliexpress links.

If you want a great portable soldering iron, I highly recommend the TS100. It was featured in voltlog #186 and I was pleasantly impressed with the performance. It had one downside, that is I couldn’t calibrate the temperature measurement perfectly but I can live with that as long as the performance is good. You can get it from banggood, ebay or aliexpress. I would recommend getting it from banggood because there are also fakes being sold on ebay and aliexpress.

If you are on a tight budget and cannot afford getting the TS100, then you can get an even cheaper portable soldering iron which is powered with a 5V usb port. I’ve used this one successfully before I got the TS100 and powered from a good powerbank I had no problem soldering 18AWG wires. Check it out on ebay, aliexpress.

If you do repair jobs on through-hole components often than you will need a desoldering gun which is practically a soldering iron combined with a pump that can suck the solder away. This is extremely useful if you do a lot of desoldering, the job gets done in a matter of seconds and with stress to the pcb and component. I have the S-993A 90W desoldering gun which was featured in voltlog #101. You can find it on banggood, ebay and aliexpress.

If you rarely do repair jobs on through hole components, than a manual desoldering pump is cheap and might work just fine for you. There are many models available and if you can afford get a good one from a known distributor, they will last longer, if not you can get a cheap one from ebay or aliexpress.

You will also need some supplies for soldering and depending on your location and budget you might find some of these brands while others are unavailable but one thing is for sure: genuine good brand solder wire and flux work so much better than cheap fake stuff.

If we are talking about solder wire, I highly recommend you get the good stuff, because it will have a fine tuned alloy that will melt and flow better while at the same time containing a flux core that will help with soldering. For hobby go with leaded solder wire, here are some good brands to search for: Kester, Multicomp, Alpha, Weller, Amtech, Loctite.

If we are talking about flux, once again I highly recommend you get the good stuff, because it will help with your soldering or repair job while at the same time leave a minimum amount of residue which can be cleaned if necessary. The fake Amtech flux that everybody buys from ebay/china works too, not as good but works. The big disadvantage is that we don’t know what they put inside that flux and we are inhaling those fumes. Also the residue it leaves on a board its pretty hard to clean when compared to the genuine stuff. As a general rule, amtech flux is made in the USA so you can’t get it for a couple of dollars from China. Get it from a known distributor: in Europe try TME, in the US try Louis Rossmann. I recommend the Amtech gel flux NC-559-V2 or ASM variant as well as various flux pens from Kester that can be used for quick jobs.

If you use flux you will be left with some residue on the board after soldering. Most flux types are no-clean type, meaning you can leave the residue on the board and it won’t affect it, however it’s nice to have clean boards so I recommend you get yourself some flux cleaner or IPA (isopropyl alcohol). I find that special flux cleaner works better than IPA in most cases. Any flux cleaner will work here and you will have to find a brand that is available in your area. I am using AG TermoPasty KontaktU because it’s available in Europe from TME. And while you are shopping for flux cleaner also add a can of contact cleaner for that odd electrical job where you need to clean the contacts on some sensor or switch.

Another chemical that is often overlooked is a soldering tip refreshing paste. This stuff will get the shine back on your soldering iron tip, making it ideal for taking solder. During extended usage, because of the high heat and the corrosive action of the flux used for soldering, the soldering iron tip might become oxidized.

So you put the tip inside the refreshing paste and it will clean it. This shouldn’t be used constantly, but only when needed because the past is moderately aggressive so it might wear out your tip prematurely. I use the Mechanic MCN-8S which is a Chinese brand which I find works well and it’s fairly inexpensive. You can find it on ebay and aliexpress.

My preferred method for cleaning the soldering tip is brass sponge. I don’t like the wet sponge method because it applies a thermal shock to the tip, lowering the temperature. The brass sponge is more abrasive and will wear out the soldering tip faster if you overuse it but I just find it works better for me. You can find these on ebay and aliexpress.

Some people use them, some people don’t. I have a magnifier & helping hand combo that even has some LED lights but I only use it once or twice a year. I don’t need magnification when soldering and if I would need magnification I would get a fancy microscope for soldering. Here is the one I have: banggood and aliexpress.

I use a cheap ESD mat and I also have a smaller silicone mat for soldering jobs because the ESD mat I have does not offer protection for higher temperatures while the smaller silicone mat will hapily take the soldering iron or some hot air without melting. There are newer fancy silicone mats that even have different compartments for storing screws, here are some links here: banggood, aliexpress.

As for the ESD mat you might find a local supplier that sells good quality ESD mats or you can order one like I did from aliexpress.

Tweezers are important, they help you handle small smd parts or wires, while soldering them but they can also be useful for other tasks. If you can afford it, get a good quality set, they will last longer and provide a better experience while using them. Good tweezers like the ones from Knipex tend to cost about $15 a piece so instead I’m using cheap tweezers that I usually get from banggood or aliexpress but I do plan on getting one or two of the good ones.

I use a cheap hobby knife (ebay or aliexpress) and cheap replacement blades (ebay or aliexpress). Sure the handle is not great and the blades don’t last very long but they are so cheap that it feels okay replacing them whenever I need a fresh blade.

And that’s pretty much all I use on the bench, if you have any questions, leave a comment below.

Voltlog #190 – Bad Product Design

Welcome to a new Voltlog, today I’m gonna talk about bad product design but not in general, I’m not gonna cover all of the things that could go wrong in product design, I am gonna focus on a particular case that I encountered recently which is related to standby power usage.

So if you’re gonna design a product that’s gonna be spending most of the time in standby, I’m talking about a product that has a soft power switch, so the product will spend most of the time in standby waiting for you to press the power up button, maybe once a day, or even multiple times, but then it will go back to sleep until next case. You would of course want to optimize the power usage in standby because that could potentially drain the battery and when you wanna turn it on, there is no more juice left.

But it seems like this simple concept is not really used, even now in 2018, you would think, every product designer would master this simple concept but that’s not the case.

Voltlog #186 – TS100 VS Generic T12 Station

Welcome to a new voltlog, today we’re talking about the TS100 portable soldering iron, but this won’t be a review because there is no point in making a review video for this mode. There are only a few things you can test with a soldering iron and there are already some very good reviews on youtube from known channels.

I am however interested in how will this iron compare with the stm32 soldering station that I’ve been using for a couple of years. So if you haven’t seen this before, I’ve shown it in detail in voltlog #85, this is a station which I got about 2 years ago, directly from taobao with the help of a friend who lives in China. At that time it wasn’t widely available so it was a bit of a gamble but it payed out because it uses hakko T12 tips and I have a bunch of different models of those and it payed out because the station works great. Nowadays you can find similar models on aliexpress so I will place a link in the description below if you would like to take a look.

I am curious though to see how this would compare with the newly acquired TS100 soldering iron. The TS100 uses a similar type of tip which has the heating element and the thermocouple built in, that type of construction ensures great thermal coupling so the tip can really transfer the heat to the joint and at the same type the sensing element get’s a very accurate reading of the tip temperature and can compensate for that.

Voltlog #175 – Aneng AN302 Pocket Multimeter Review & Teardown

Welcome everyone, review time again, today we are taking a closer look at this pocket multimeter. It’s the Aneng AN302, 8000 count, true RMS multimeters. It comes with this black pouch and inside, the meter is wrapped in some bubble wrap. I don’t know about you but when I’m receiving stuff from China it always contains this popped bubble wrap, have you noticed the same? I wonder why the bubble wrap is already popped, cause it kinda defeats the purpose.

Here are some links where you can order the Aneng AN302 Pocket Multimeter: Aliexpress, Amazon, Ebay, Banggood.

Here are some links with the other items mentioned in this video:

Here is the pocket multimeter spreadsheet where I list all the meters I’ve looked at.

Voltlog #174 – UNI-T UT125C Pocket Multimeter Review

Hello and welcome everyone, today it’s review time and we are taking a look at the UNI-T UT125C Pocket Multimeter. This is a 4000 count, CAT III 600V pocket meter they claim but as we’ll see in a moment it’s a bit bigger than an actual pocket meter.

Here are some links where you can order the UNI-T UT125C Pocket Multimeter: Aliexpress, Amazon, Ebay, Banggood.

Here are some links with the other items mentioned in this video:

Here is the pocket multimeter spreadsheet where I list all the meters I’ve looked at.