Voltlog #207 – Making a DIY Spot Welder From A Microwave Transformer

Welcome to a new voltlog, today I’m gonna talk about a DIY spot welder that I built, the advantages of suck a build as well as the disadvantages or the the problems I encountered. So the idea for this project started many months ago, I was actually at a local recycling center to deposit some old electronics, when I saw this microwave oven transformer sitting right there on a table, like the guy in charge of the place literally took the transformer out of a microwave oven a few hours prior to me arriving there.

So that sparked the idea in my head, I asked the guy if I can have the transformer, he said yes and that was the start.

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 banggoodebay 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 #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 #183 – Building A Resistance Standard With Vishay VHP100 Resistors

Welcome to a new Voltlog, today I’m going to be building a precision reference box, using these precision Vishay resistors, they were sent to me for free by Vishay, these are from the VHP100 series and they are the ducks guts when it comes to resistors. They have incredible stability, across the entire range of -55 up to +125 degrees Celsius they will vary less than 60ppm. So as you can see they had to define the number over the entire temperature range because if they would have done it traditionally per degree C the number would have been essentially 0.

These are built using a special technology called bulk metal foil, wrapped on a ceramic substrate. Then the assembly is suspended in oil and hermetically sealed in this metal can, thus it’s immune to humidity changes. Every one of these resistors is basically custom made so you can order them in any value, but as expected they don’t come cheap. Purchasing these in some standard values carried at the big distributor will cost you around $70 a piece.

Voltlog #179 – How To Solder Through-Hole Parts

In this video I’m gonna show you how to solder through hole parts. I’m gonna take you step by step through the procedure as well as give you several tips & tricks that should bring your soldering skills to a new level.

Links for all the tools and parts shown in this video are placed in the video description.

Voltlog #161 – How To Assemble SMD Parts

In this video I’m gonna show you 3 methods to solder SMD parts but before we get to the actual methods I think it’s best to talk about the type of solder to be used. And there are two main types of solder that you can use, that is leaded or lead free solder. If you are doing prototype work it’s best to stick with leaded solder or solder paste because it’s easier to get right, it has a lower melting temperature. If you are doing production work, you plan to sell those boards, than you might be forced to use lead free solder to be compliant with the regulation.

Here are links to the items shown in this video:

Voltlog #155 – TL431 0-15V 0-5A Adjustable Power Supply Kit 3AG1 Xiaolin

A while ago I showed this power supply kit, which I ordered from ebay. It was being advertised as an LM317 0-15V 0-5A adjustable power supply kit and it looked promising. Upon receiving the kit and taking a closer look theres 2 thing to mention, one the power supply is not based on the LM317 but on the TL431, they used TL431s instead of op-amps in this power supply design and two there isn’t much documentation about this power supply.

The components used are low quality but that is to be expected from these cheap kits coming from china so no surprises there. If you would like to use some better quality parts I would suggest replacing the electrolytic’s and the TL431s with ones sourced from known sources. Also a nice upgrade would be to use some 10 turn pots instead of the supplied ones to get some finer adjustment. But I just used the originally supplied parts to see what kind of results we get with those.

Get the TL431 power supply from these links:

Here is a screenshot with the signal measured right on the bulk filtering capacitor (4700uF). Looks like this might be the cause of the 100Hz oscillation we we’re seeing on the output.

Here is a screenshot with the current overshoot. The power supply was set for CC 50mA and I suddenly shorted the output through a 1ohm resistor. The scope probe was placed across the resistor leads on the low side ( 1mV = 1mA ). As we can see we have a huge spike of current that could potentially fry an LED connected on this power supply. However the spike lasts less than 1mS which is good and I have observed similar behavior on my HP E3611A analog bench power supply.

Here is also a screenshot with the power supply regulating the current at 50mA in CC mode. This doesn’t look right at all.

Voltlog #154 – Making My Own Trezor Crypto Hardware Wallet

In this video I’m gonna show you how I build my own Trezor hardware wallet. If you would like to support the voltlog channel checkout the donations page where you will find my paypal address or different crypto wallet addresses.

If you encounter this error while trying to compile trezor firmware:

Traceback (most recent call last):
 File "nem_mosaics.py", line 6, in <module>
 from google.protobuf import json_format
ImportError: cannot import name json_format
Makefile:121: recipe for target 'nem_mosaics.h' failed
make: *** [nem_mosaics.h] Error 1

It can be fixed by installing googleapis-common-protos package like this:

sudo pip install googleapis-common-protos

This fix was posted in the comments section by a viewer, I verified and it works.

Voltlog #140 – ISDT Q6 Plus Lipo Charger Repair

Welcome to a new Voltlog, this will be a repair video, because my ISDT Q6 Plus battery charger has failed. If you remember Voltlog #109 I did a review of this charger and I’ve been using it quite often since I got it, with no issues whatsoever, until a few days ago, I think I was just storage charging some batteries, I did 2 batteries and when it was time for the 3rd battery to go on it would not start anymore, it was saying, “current operation is not supported”.

Get the ISDT Q6 Plus here: