Etching a PCB In Ten Minutes.

Most circuit boards any maker could need for their projects can be acquired online at modest cost, but what if you need something specific? [Giorgos Lazaridis] of pcbheaven.com has designed his own etching bath complete with a heater and agitator to sped up the process of creating your own custom circuit boards.

[Lazaridis] started by building a circuit to control — in a display of resourcefulness — a fish tank heater he would later modify. The circuit uses a PIC 16F526 microcontroller and two thermristors to keep the temperature of the etching bath between 38 and 41 degrees Celsius. The fish tank heater was gingerly pried from its glass housing, and its bimetallic strip thermostat removed and replaced with a wire to prevent it shutting off at its default 32 degrees. All of it is mounted on a small portable stand and once heated up, can etch a board in less than 10 minutes.

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Electroshock Timer Will Speed Up Every Game of Settlers of Catan

The fun of playing Settlers of Catan is only matched by the desire to punch your friend when their turn drags on with endless deliberating. [Alpha Phoenix] has solved that quandary of inefficient play by building the Settlers of Catan: Electroshock Therapy Expansion.

[Alpha Phoenix] is holding back on the details of the device to forestall someone trying this at home and injuring themselves or others, but there’s plenty to glean from his breakdown of how the device works. An Adafruit Trinket microcontroller connects to a single pole 12 throw switch — modified from a double pole six throw rotary switch — to select up to six different players (with the other six positions alternated in as pause spaces) and the shocks are delivered through a simple electrode made from a wire hot glued to HDPE plastic from a milk jug. The power supply is capable of delivering up to 1100V, but the actual output is much less than that, thanks to its built-in impedance of about 2.5M Ohms, as well as added resistance by [Alpha Phoenix].

To define what constitutes a ‘long turn,’ the Trinket calculates the mean of up to the first 100 turn lengths (instead of a static timer to accommodate for the relative skills of the players in each game) and zaps any offending player — and then repeatedly at a set time afterwards — to remind them that they need to pick up the pace.

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Materials To Know: Tooling and Modeling Board

I was in a fit of nerd glee the first time I used tooling board. I’d used MDF for similar purposes before, and I doubt I ever will again. Called Renshape, Precision Board Plus, or that green stuff people on another continent buy; it’s all the same extremely useful, unfortunately expensive, stuff. It’s hard to pin down exactly what tooling board is. Most of the blends are proprietary. It is usually a very dense polyurethane foam, sometimes by itself, sometimes with a fine fiber filler.

What makes tooling board so good is its absolute dimensional stability and its general apathy to normal temperature swings. (It even comes in versions that can go through curing ovens.) It is impervious to humidity. It has good surface finish, and it machines perfectly without wearing down tools.

The CNC set-up I coaxed precision molds out of.

This stuff is really tops as far as machining goes. I got super precise molds out of a very basic CNC machine at the LVL1 hackerspace. Renshape cut easily at a high spindle speed, and put practically no load on the machine. Climb and conventional milling were equal load wise with no immediately perceivable difference in finish. In the end I hit the precision range of my cheap digital calipers: +-.005mm, when the temperature is right, the battery is a charged, and the planets align.

I like to do resin casting when I get serious about a part. If you are making a master mold, there’s nothing better than tooling board. I’ve used both Renshape 460 and Precision Board Plus. Both impart a very light matte pattern, equivalent to a light bead blast on an injection mold. There’s no finishing required, though I mistakenly bought Renshape 440 at first and had to sand it a little to get the finish I wanted.

Tooling board is great for masters in metal casting, and is often used in the industry for just that, especially if quick and accurate prototypes are needed. It’s also tough enough to last through a few rounds of metal stamping in the home shop.

If you are doing lay-up for carbon fiber, fiberglass, or leather, this is also a very good choice. It will be unaffected by the chemicals, heat, and vacuum you may use in the process. It is tough enough hold alignment pins for proper set-up without premature ovaling. It is also a very good choice for vacuum forming.

Tooling board is, unsurprisingly, really good for tooling. It’s a great material for soft-jaws, alignment fixtures, and assembly fixtures, especially if you are doing delicate precision assemblies.

If you’re made of money, tooling board can be used for models, signs and props. It sands, shapes, and files extremely well. It bonds well to a lot of substances. It also takes paint very well with none of the absorption properties of wood or MDF. Most professional model shops will use it.
2015-11-05-10.34.01The one big flaw of tooling board is its price — this stuff is expensive. There’s no good DIY version that I’ve scrounged up so far. If you’re making a mold master, a fixture, or anything where you need tooling board’s properties and you are likely to get a few uses out of the board, then it’s probably worth it. Also, be careful of sellers selling plain “Renshape” it is probably going to be the lower grade Renshape 440 and not the more expensive Renshape 460 (or equivalent), where you start to really see the surface finish advantage of the material.

Tooling board is an industrial material. Typically you can call up a supplier and tell them what you’d like to do with it and they will be able to help. If you are making tools for carbon fiber quadcopter frame lay-up, let them know and they’ll have a formulation for that. If you are resin casting, there’s a formulation that gives superior surface finish.

It’s a pretty common material in the industrial scene, but I don’t see it a lot on the hobby scene. This is almost certainly due to its cost, as well as a shortage of small quantity re-sellers. (If someone starts selling assorted sizes on eBay for a reasonable price you have at least one buyer in me.) However, after using it in the niches it is designed for, I really don’t use anything else. I used to hack MDF to fit, but MDF is awful to paint, has no dimensional stability, and dulls tools really fast.

Are you a fan of tooling board? Have a good source? If you have anything to add, let us know in the comments.

Bitten By PCB Defects

If you’ve ordered PCBs from Seeed Studio, ITead, DirtyPCB, or another board house in China, you’ve probably noticed that neat little 100% e-test option available on the order form. If you select this, the board house will throw your PCBs in a machine that will poke a pin in every pad to make sure all the connections are good. Less work for you, right? As [Andy] found out, not always. He was bitten by a manufacturing defect that sheds some light on what that e-test actually is, and the capabilities of what these Chinese board houses can do.

Most of [Andy]’s project have a lot of surface mount components, and when he receives his boards, he notices a few pin pricks on each and every pad. This is from a flying lead machine; a robotic continuity checker that makes sure all the relevant pads are electrically isolated from each other.

One of [Andy]’s recent projects is an entirely through-hole design. Apparently these robotic meters don’t test through-hole pads; it’s significantly harder to measure the continuity of a hole rather than a pad, apparently. After assembling one of these boards, he noticed a problem where one of the GPIOs was permanently high. The offending trace was found underneath a DIP socket, in precisely the worst possible place it could be.

If [Andy] had inspected the board beforehand, this problem would have been avoided. He says it was a relatively simple board with big traces and wide spaces and he didn’t think a manufacturing defect was possible. He was wrong, and now we have a warning. We thank him for that.

Computer Built into a Board Uses Only 10 Watts

In the realm of low-powered desktop computers, there are some options such as the Raspberry Pi that usually come out on top. While they use only a few watts, these tend to be a little lackluster in the performance department and sometimes a full desktop computer is called for. [Emile] aka [Mux] is somewhat of an expert at pairing down the power requirements for desktop computers, and got his to run on just 10 watts. Not only that, but he installed the whole thing in a board and mounted it to his wall. (Google Translated from Dutch)

The computer itself is based on a MSI H81M-P33 motherboard and a Celeron G1820 dual-core processor with 8GB RAM. To keep the power requirements down even further, the motherboard was heavily modified. To power the stereo custom USB DAC, power amplifier board, and USB volume button boards were built and installed. The display is handled by an Optoma pico projector, and the 10-watt power requirement allows the computer to be passively cooled as well.

As impressive as the electronics are for this computer, the housing for it is equally so. Everything is mounted to the backside of an elegant piece of wood which has been purposefully carved out to hold each specific component. Custom speakers were carved as well, and the entire thing is mounted on the wall above the bed. The only electronics visible is the projector! It’s even more impressive than [Mux]’s first low-power computer.

A Router-Based Dev Board That Isn’t A Router

Here’s somethirouterng that be of interest to anyone looking to hack up a router for their own connected project or IoT implementation: hardware based on a fairly standard router, loaded up with OpenWRT, with a ton of I/O to connect to anything.

It’s called the DPT Board, and it’s basically an hugely improved version of the off-the-shelf routers you can pick up through the usual channels. On board are 20 GPIOs, USB host, 16MB Flash, 64MB RAM, two Ethernet ports, on-board 802.11n and a USB host port. This small system on board is pre-installed with OpenWRT, making it relatively easy to connect this small router-like device to LED strips, sensors, or whatever other project you have in mind.

The board was designed by [Daan Pape], and he’s also working on something he calls breakoutserver There’s a uHTTP server written specifically for the board that allows any Internet connected device to control everything on the board. There’s also an HTML5 app they’re developing which could be pretty interesting.

All in all, it’s a pretty cool little device that fits nicely in between the relatively simplistic ‘Arduino with an Ethernet shield’ and a Raspi or BeagleBone.

Help identify this vintage electronics component

mystery_board

[Windell] over at Evil Mad Scientist Laboratories has reached out in order to help them identify a mystery piece of electronics equipment they came across a few years ago. Discovered at an electronics surplus store, the mystery component looks like a cross between an over-sized chess board and a breadboard. Failing to identify it they eventually disposed of the board, snapping a couple of pictures for good measure before it was gone for good.

Recently while visiting a local electronics flea market, they came across what looked to be a similar, though much smaller board. This piqued their curiosity and compelled them to dig out the pictures of the mystery board in hopes of finally discovering what it was. Using markings on the new board they found, the team at EMSL located some images of a patchboard cartridge that looked quite similar to their mystery object. Upon closer inspection however, they think that the two pieces might be related, but are not quite the same item.

Swing by their site and chime in if you happen to have any good leads – we’re sure they will appreciate it.