Voltlog #101 – S-993A 90W Desoldering Gun

This is a short review of the S-993A 90W Desoldering Gun which was sent to me for free by banggood.com. I was planning on getting one of these for a long time and I’m happy that I finally got it, it’s very useful in repair jobs as I’m showing in the review video below.

Links for buying this desoldering gun:

EasyEDA PCB Service Review

I’ve talked about EasyEDA in the past in Voltog #58 where I reviewed their free online pcb design software. Now the guys from EasyEDA asked me if I wanted to review their pcb service and I said yes. They offered to fabricate my pcb’s for free and also included a steel stencil.

The design for these pcb’s is my dark load project, the electronic dummy load that I’ve started working on over a year ago but never got around to finishing the project. The main reason for not finishing the project was because I don’t like writing code that much so after spending some time on the STM32, writing code for testing the on-board hardware, initializing the OLED display and the ADC I got bored and kinda stopped working on the project.

However there were some hardware improvements that I planned to do on that design, especially with the fan pwm control circuit. I wanted to switch to an inverted buck dc-dc converter topology driven from the microcontroller with PWM. This way I would get a nice varying dc voltage that would reliably vary the speed to any type of dc fan connected, but that’s another story.

Just so it happens, I recently reviewed the pcb assembly service from 7pcb.com so I have a spare blank pcb from their service so we can use this pcb which is an identical design for comparison. The only difference is that EasyEDA does not offer a matte black soldermask finish so I had to go with normal glossy black on their service.

How is the ordering process on EasyEDA?

The ordering process is an important part that might help you decide whether or not you will order from a specific shop. If you go to EasyEDA PCB ordering page, you will be greeted with a simple layout, you just need to drag&drop your gerber files and select the various options for the pcb panel.

They let you select the quantity, pcb thickness, soldermask color, surface finish, copper weight, temp rating, holes/traces/spacing, pretty much standard options with every board house these days.

You can also check an option to get a steel stencil if you need it and in the end you will get a build time estimate, a price estimate and you can also simulate the shipping cost. In my opinion this is a pretty straightforward, easy to use ordering form.

I ordered two pcb designs: first was 100x60mm ($75 for 5pcs with steel stencil) second was 106x55mm ($57 for 5pcs), black soldermask, ENIG finish. The total cost was $132 plus shipping. Shipping to Romania via DHL was another $37.

How is the silkscreen quality?

Unfortunately I no longer have my microscope so I am only using a macro lens to take close-up pictures of the pcbs but we can still observe the silkscreen quality and resolution in the picture below.

The vertical copper pads are 0.6×1.9mm in size and the text block saying “FRONT” is about 5.7×1.2mm. The printing on the 7pcb.com panel looks to be a bit sharper, not by much, just a bit. We can also notice EasyEDA placed some text under that connector on the top side of my pcb. Personally I don’t like it when they place text on my pcbs, but at least in this case they placed it under a connector where it would never get seen after the assembly.

Soldermask expansion and alignment

The soldermask alignment is not perfect but certainly acceptable and comparable between the two. It’s shifted on the same axis on both panels, but it doesn’t obstruct the copper pad in any way so that is perfectly acceptable, especially considering those passives are 0603 so the actual size is quite small.

The panel from 7pcb.com seems to have tighter tolerance for mask expansion and alignment but as I mentioned, the one from EasyEDA will work just as well as there is no pad obstruction happening.

No soldermask between the microcontroller pads for the EasyEDA panel while we have the mask on the 7pcb.com panel. I am not sure if 7pcb.com have a better more precise process for the soldermask application or is it just something specific to the matte black soldermask, maybe a different process specific to the matte black? Overall the soldermask print was uniform and without any scratches or problems on both panels.

Holes offset

This is where a microscope would of been handy because just with a macro lens is not really possible to get a feel for the holes offset.

These are 0.7mm drill holes in the fan connector and they look very well aligned on both panels. Maybe just a very small offset on the 7pcb.com panel but that is perfectly acceptable and won’t cause any trouble.

Overall very good drill hole alignment with no or very minimal offset on these two panels.

What about the steel stencil?

As mentioned in the start of this article I also got a steel stencil with this order to make the assembly work easier. There isn’t much you can review or say about a steel stencil. It was shipped nicely sandwiched between two pieces of plywood so it wouldn’t get damaged during shipping. It’s your standard frameless laser cut stencil that you can get from most pcb fab houses.

The specs for this laser cut steel stencil are: no frame, 0.12mm thick, no fiducials, no eletropolishing (electropolishing removes the micro burrs associated with laser cuts, leaving behind smooth aperture walls for easy transition of paste from the stencil to the pads), 280×380 size for a cost of $17.9 and 0.7Kg added to the shipping weight. On their website you can select multiple options but I went with the standard ones.


Although I don’t have any cost information on the 7pcb.com panel, I think the price should be similar so it was a fair comparison.  In terms of the ordering process EasyEDA have clearly invested in their online platform so the ordering process is very smooth and fast.

The quality of these pcb’s is very similar but the one from 7pcb.com stands out in a few areas like silkscreen quality and soldermask expansion and alignment.

Should you order pcbs from EasyEDA? I’m tempted to say the pcb’s from EasyEDA would directly compete with the ones offered at a lower price by shops like SeeedStudio Fusion, Elecrow, DirtyPCBs, and others. A fair comparison would be to order the same pcb from one of these lower cost shops and check if they are the same quality. If they are the same quality then, I wouldn’t recommend buying something more expensive unless you benefit from something else like the ordering experience.

For example if you are using EasyEDA online cad tool, then it would simply be a matter of a few clicks to get your design into production. In that case it might be worth to pay extra because it will save you time.

I think hobbyists who usually don’t need any extra bells and whistles will continue to order from the cheapest service available because they just need one-off pcb designs for their small projects and they don’t care how fast the order is processed or how the ordering process goes, they just want the cheapest option possible.

Voltlog #58 – EasyEDA Free Online PCB Design Software Review

The guys from EasyEDA contacted me and asked if I could do this review I accepted and they’re also going to be offering some free coupon codes for my viewers which you can use to order PCBs but more on that towards the end of this video.

EasyEDA being a cloud app it’s supported on every platform / operating system. You get schematic capture, circuit simulation and pcb layout functionalities. You can import files or projects created with other design tools like Eagle, Kicad or Altium and i’m sure it does most of the things that every pcb design tools does.

You can share and collaborate with other people on your projects so that’s a big selling point for EasyEDA and they made sure to put that on their front page. And I’m sure a bunch of other features that are not mentioned on their homepage and best of all you always get to work with the latest version because the app is on the server not on your computer. Another good thing is that you have the whole process from design to finished PCB on one single app or service and you just click through until you get the PCBs at your door and that might be a big advantage for some people.

Now, ofcourse a big concern with these kind of web based apps is what happens if they decide to shutdown the service? Well the guys from EasyEDA say that if they ever decide to shutdown the service they will open source the code and allow people to download all their projects so in theory you are covered, you could host your own server if that ever happens.

For more info, you should watch the video below.

Voltlog #48 – New 2016 Gopher CPS-3205C Review & Teardown

This is the new 2016 revision of the Gopher CPS-3205C. Gopher has addressed some of the issues I found in the old revision and sent me their latest for review. You will see a teardown as well as various tests performed on this power supply.

Review PCBcart vs OSH Park vs Smart Prototyping

This review/comparison might seem unfair at first because the PCB’s I got from PCBcart do not exactly count as hobby pcb’s due to their features and higher value but some of you might not put cost first on their list we can still get some useful points out of comparing these three.

I was working on designing a pcb for a new project when I was approached by someone at PCBcart who asked if I was willing to review their pcb service. I said yes and they offered to manufacture and send me the pcb’s for my project for free.

The price calculator and ordering system is fully automated on their website, you just fill in the details, you get a price quotation, next you upload your gerber files and place your order. A day later after submitting my files I was contacted by someone who was reviewing my gerber files. They noticed I had routed slots in the milling layer so they asked if they should route those through the middle of the marking line or in another way, thus getting the intended finished slot dimension.

They also noticed I had some square smd test points/pads which were also present in the stencil/paste layer and they asked if I want those in my stencil or not. This is something you might overlook and you might not want those present in your stencil if you plan on using those pads for programming, for example with some pogo pins in a jig. If that’s the case you want your pogo pins to touch directly the pcb pad, you don’t want any solder in between.

After exchanging some emails on those points my order went through manufacturing and I was notified it has been shipped with DHL. About 5 days later I had the boards in my hands and let me tell you these must be the most beautiful PCBs I ever had manufactured.

the dark load pcbcartthe dark load pcbcart the dark load pcbcart





This is mostly due to the nice gold plating and the matte black soldermask. Definitely perfect for making front panels as I intended for one of these pcbs.

So let’s go through some things and compare these 3 pcbs. First let’s take a look at the quality of the silkscreen. All three have white silkscreen and I tried to get similar sized text for comparison. All images have been captured under my low cost microscope, at the same magnification level on the same flat bed surface.

Unfortunately the pcb from OSH Park doesn’t have any silkscreen, I don’t remember why, it was a prototype I did a while ago. The most likely scenario is that I forgot to export the silkscreen layer in my gerber files.


In this case, the result is quite clear, much better printing from PCBCART, they seem to have a higher resolution print. Most of you might not care to pay extra just for a better silkscreen but then again there might be some people who are designing for example a front panel pcb which needs a nice higher resolution silkscreen.

Next let’s take a look at soldermask alignment. In this category we can compare all three, and let me explain first that, with bigger mask relief (that is the clearance from mask to exposed copper pad) it is easier to handle offsets of the soldermask with regard to the actual copper layer. So I think, manufacturers that can’t maintain a tight tolerance on their mask alignment just increase the relief to make sure the mask never accidentally covers what should be an exposed pad.

soldermask tolerance

On this point, PCBCART again seems to be the best, I don’t even know what kind of process they use, but judging from the photos that I could get with my microscope, it looks like the soldermask extends right up to the copper pad with perfect alignment.

The spacing between the copper pads is also marked on the image and that is something to consider because with very low spacing some manufacturers cannot guarantee soldermask in between those pads. Having no soldermask in between pads might affect your soldering quality, you might get solder bridges more often for example. And in this test, the pcb from Smart Prototyping doesn’t get any soldermask in between those pads.

Next, let’s take a look at via/hole registration. This becomes quite important when working with small drill sizes like 0.3mm and below. You want your pcb to have that hole drilled right in the middle of the pad/via to ensure even copper distribution around it.


Starting from the left, we have PCBCART with a 0.5mm drill via, with excellent registration, clearly the winner judging by the even copper surface all around the drill hole. Next we have OSH PARK with 0.3mm tinted via, very good registration, no problem at all. And on the right we have Smart Prototyping probably 0.4mm drill tinted via, with a small offset.

And just for fun let’s take a look at one more thing, routed slots. In both PCBCART and Smart Prototyping boards I have some routed slots and the idea to compare this came to mind while holding the boards in my hands, I noticed one of them had cleaner slots, with less rough edges. I tried capturing this under the microscope but the results are not that great.


The one from Smart Prototyping seems to have some rough edges on the inside of the routed slots but once again this is just something i noticed while playing with these pcbs, probably not something you would be worried when ordering your next pcbs.

So to conclude my experience with PCBCART, their website is great, you get all the info you need there and the process of ordering is very streamlined. Their customer support was very professional, not wasting time at all and the pcb quality was superb, the pictures speak for themselves.

And one other thing I liked about them, you know those nasty identification numbers that every pcb manufacturer puts on your pcb so they can identify it through their manufacturing process? Well sometimes we are designing front panels, and we don’t want those numbers visible on our pcbs and so far, no manufacturer ever listened to my request, not by email and not by a readme file archived together with the gerbers files. They all went ahead and put those numbers on my pcbs regardless of my request.

Well, pcbcart was the first ever to actually follow my request and not place any additional markings on my pcbs.

And if you’re curious about what the Dark Load is, subscribe to my voltlog youtube channel as more information will be posted there in an upcoming video.


VoltLog #20 – Mastech MS6612 Light Meter Review & Teardown

In this video I’m doing a product review and teardown of the Mastech MS6612 Digital Light Meter. I am also taking a look at a typical 9V battery datasheet and make an estimate on the usage hours  that I’m going to get for this meter.