Got To Blinky

Recently, for reasons I might get to here a little later on, I started thinking about drawing circuit schematics and making PC boards. I did some stuff with the EasyEDA site and I might go back to working with that, I don’t know, but I started feeling like I wanted to try out other options. I installed KiCad on my Linux machine and then followed the series of video tutorials offered by Contextual Electronics, a playlist called Getting To Blinky 5.0. I guess I must have liked them; I was up until about 3:20 am watching them, following along in KiCad with drawing the schematic, laying out the parts on the circuit board, drawing in the PCB connections, and ultimately coming up with a design for a little (about 30 by 30 mm) board with a few components and a battery holder.

It’s designed to do much the same thing as the SMD tutorial kit I built several months ago: Blink an LED. And in fact before I went to bed, I uploaded my design to OSH Park and placed an order for three copies of the board.

I mean, I figured I could use some more SMD practice before my next module. Especially since the SMD module after that will be one that uses 0805 parts rather than 1206 (i.e. 0.08″ by 0.06″ instead of 0.12″ by 0.06″), and so does Getting To Blinky.

That whole exercise altered my viewpoint. The electronics I’ve done until now has used either PC boards designed and fabricated by someone else, or something like perfboard. I used perfboard for the Ribbon Controller Interface and for the added components in my Echo/Reverb module. I’ve considered stripboard but never tried it. Recently I watched a couple of videos about PCB etching at home. Seems relatively easy though it involves some obnoxious substances and tedious processes, and seems questionable for any but simple, single layer boards — or at least, doing anything more complex would likely be significantly harder.

But I’d been under the impression getting PCBs made would be pricey and worthwhile only if you’re making them in quantity. And that ain’t so. I got my three boards made and shipped for under $7.50. Granted, they’re pretty small. Still, that’s not much money.

And it can be even less. If you don’t mind getting your boards fabbed in China, PCBWay has a good reputation and will do five or ten copies of a board up to 10 cm by 10 cm for $5 (total! Not each!) plus shipping. But wait! JLCPCB also has a good reputation and their price for five boards, or ten, is $2! That may be a limited time special price; it might be $4 normally. Shipping is more than for OSH Park, but if you’re not in a hurry it’s around $6 or $8 for five small boards.

Of course if you’re in a hurry either you’ll pay a good deal more for shipping and for fabrication closer to your home, or, if you’re in genuine panic mode, making them yourself may be your only option. But otherwise, any of these companies can make a few (small) boards for less than a Big Mac combo meal.

How about a Eurorack module board? That’ll run you more than a Getting To Blinky. Consider a front panel for a 12U module. (Your printed circuit board doesn’t have to have a circuit on it. Most of these places will cheerfully follow a design that has just holes and silkscreen on it, making something more or less suitable for a front panel.) That’s 61 mm by 129 mm, which comes to 12.2 square inches. OSH Park charges $5 per square inch for three copies of a board, for any number of boards provided it’s a multiple of three, and that comes out to $61. It’s only $1 per square inch for an order of a multiple of ten boards and a minimum of 100 square inches total, so ten 12U panels would be $122.

From PCBWay, they quote a price of $24 for five 12U panels. Again, that’s without postage, but slow shipping doesn’t cost much.

As for JLCPCB: five 12U panels cost $6.70. Ridiculous!

One might prefer PCBWay, though, if one wants more choices of things like board materials (including aluminum), board thickness, silkscreen color (black or white), and so on. PCBWay also offers more choices of solder mask color than JLCPCB (9 versus 6). OSH Park offers only purple and clear (over a black substrate!)

Why mess with ferric chloride and acetone and cutting and stirring and scouring and drilling? No thanks. And maybe for something as trivial as the Echo/Reverb module, where I only needed to mount a header, a pot, and a resistor, perfboard really was the way to go, but if I were doing even something as simple as the Ribbon Controller Interface again, I think I’d design a board and get it fabbed.

Anyway, my Blinky boards arrived a few days ago and the parts to assemble them arrived yesterday.

I put one of the boards together. It went… okay. It’s very clear I need better tweezers, pointier and less messed up. That order’s gone in. I got it done anyway, making less use of tweezers and more of a toothpick than is necessarily desirable. I shoved in a CR2032 battery and… nothing happened. I reheated some joints, checked some continuities, no dice. Finally, long story but I happened to discover the circuit worked if I put 5V on it instead of the 3V battery. On further investigation it appears the LEDs I got, in series with a 1k resistor, need at least 3.5V to barely light up at all. The Getting To Blinky videos didn’t specify the LED to use and it would appear my criteria to select one were… inadequate. Well, so what? The circuit board is good, the soldering is adequate, the thing works for certain values of works, and that’s enough for me.

Postscript 25 Feb 2020: Here’s a site which allows you to comparison shop between a lot of PCB companies. And which sells ads to PCB companies, so yeah. Anyway, I entered 61 by 129 mm and 3 board minimum and left everything everything else the default. With the lowest postage rates to the US, the cheapest were:

Company# Boards# Shipped price
Smart Prototyping5$26.61

Of course the results will vary for different board sizes, quantities, and options. (You can enter a number of different options in PCBShopper; one I noticed isn’t there is board material.) AISLER is in the US, the rest of the seven above are in China. There are about 16 others (including OSH Park) with higher prices. There are star ratings based I guess on site user reviews, and for what it may be worth the ones with 10 or more reviews are:

CompanyStar rating
OSH Park4.5
Smart Prototyping4.0
ITEAD Studio3.5
Seeed Studio3.1
Advanced Circuits2.5

So JLCPCB is significantly the cheapest, with rating in the second tier; Elecrow has the combination of being one of the lowest priced (but double JLCPCB) and the highest rated.

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