Level converters to make all your hardware (5.5V and under) play with each other


I finally set aside some time for one of my own projects. I have been playing around with ARM microcontrollers a lot lately and wanted to try out my GLCD display that uses the KS0108 protocol. It’s 5V but I had heard that some of these displays will work with 3.3V TTL. But the datasheet tells me otherwise. I tried using a pull-up resistor to 5V and configuring the Stellaris Launchpad pins to open drain, but the low voltage wasn’t getting below the 0.3V threshold needed by my display. My only choice was to use some type of level conversion. I actually ended up driving the KS0108 using a pair of TXB0108 level converters.

I figured this had to have been done before so I check over at Sparkfun. Their offerings are either one-way or have a direction pin that you must drive yourself. I figured there had to be a bi-directional solution and a search over at Mouser led me to the TXB0108. It is exactly what I was looking for and as you can see I etched my own circuit boards to make the TSSOP chips breadboard compatible. I’ve documented the process you can find the code and board files at my post linked above.

Update: one of the Reddit comments mentions this chip is available on a breakout board from Adafruit if you’re interested.

Integrating a power bus into a quadcopter frame

When working on flying vehicles weight is always a consideration. [Brendin] found a way to get rid of a wiring harness on his quadcopter, simplifying the assembly while lightening the load. He did it by incorporating the power bus into the frame of the vehicle.

He started with some copper clad board. Because the substrate is a structural component he didn’t want to use a CNC mill to do the etching as it also removes a bit more than just copper. After using the mill to cut out the shape and drill holes he coated the board with flat black paint. This acts as the etch resist, which he sent through a 50W laser engraver to remove the paint and expose the areas he wants to etch. After etching he removed the rest of the resist, and masked off his solder pads with small rectangles of electrical tape. This protects the solder pads from the truck bed liner paint he uses to insulate the copper. He says it works great and plans to use the technique on all future builds.

Birth of an Arduino

Hey look, an Arduino without its clothes on. This one’s just started its journey to becoming the ubiquitous prototyping tool. The image is from [Bunnie’s] recent tour of the fab house where Arduino boards are made.

As it says on every true Arduino board, they’re made in Italy. [Bunnie’s] trip to the factory happened in Scarmagno, on the outskirts of Torino. The process starts with large sheets of FR4 copper clad material, usually about 1 by 1.5 meters in size. The first task is to send the sheets through a CNC drill. With all of the holes done it’s time for some etch resist; the image above is just after the resist has been applied. A robotic system takes over from here, running the panels through the chemicals which first etch away the copper, then remove the resist and plate the remaining traces. From there it’s off to another machine for solder mask and silk screen.

There are videos of each step available. But our favorite piece is the image at the end that shows a pallet with stacks of completed PCB panels which are headed off to be populated with components.

[via Reddit]

How to etch your own solder paste stencils

We’re kind of surprised we haven’t covered this concept before since it only uses techniques that are commonly avaialable for home PCB fabrication. [Ray] made this solder paste stencil out of a sheet of copper using the same etching techniques you would for a circuit board. He designed and printed a resist pattern, with toner everywhere except the places where there should be holes in the stencil. He transferred the toner to the copper using an iron.

The difference here should be obvious; this a thin copper sheet with no substrate. Because of that, you must protect the copper surface before etching. he covered the entire thing, both sides, in packing tape. After that it’s into the Cupric Chloride bath to dissolve the exposed parts. Once the tape and toner has been removed you can scree a precise amount of solder paste onto your boards.

This isn’t for everyone, but if you’re assembling many boards it’s not a bad approach. If the stencil is no longer used it can be recycled, but we do wonder how corrosion on the copper will affect the stencil’s performance.

The idea for this technique came to [Ray] from a guide that’s been around for years.

Etching your own PCBs

When [Adr1an] wrote in to share a link to his PCB etching tutorial he mentioned that he knew we had already covered a ton of these guides. He’s absolutely right, not only have we featured a great number of them, but we also wrote our own quite a while ago. But that doesn’t mean we ignore them when they come in on the tips line. In fact, we read all of them that have something to offer and are pleased to feature the ones that are well presented… like this one!

[Adr1an] went all out with his writeup. He not only covers all of the elements that go into this, but discusses where to purchase them and his thoughts on how he arrived at the choice. He’s using the toner transfer method and prefers Brother branded toner for its coverage and resistance to over-etching. He prints on HP Everday Photopaper, then uses a laminator to transfer to the copper clad board. For this guide he used 2oz copper but prefers 1oz copper as it etches faster. His etchant of choice is Ferric Chloride, which can be ordered as a dry powder. He uses the direct etch method of loading etchant into a sponge an applying that to the board.

The board he makes in the guide looks great, and it only took him 28 minutes!

Tour of Advanced Circuits – A PCB Manufacturer

Although not a hack in itself, many of you may be interested in seeing how a printed circuit board is made in the manufacturing world.  This tour of Advanced Circuits does a good job of explaining the process. The article explains how a PCB will go through a CAD/CAM review, drilling, deburring, and the various chemical etch, plating, and curing processes.

Although many hackers make their own PCBs, having it professionally done can be a good option depending on how many copies are needed. One benefit of this is that PCBs can be checked by an optical inspection process, or even by a “flying lead” machine which works by contacting leads automatically in a computer controlled setup.

A video of this incredible machine is included after the break.  Around 0:26 is when it really starts to get going. Continue reading “Tour of Advanced Circuits – A PCB Manufacturer”

Direct to PCB resist printing requires minimal additional components


Printing PCBs using the toner transfer method works pretty well, but there are some downsides, such as incomplete trace transfers and the like. HackHut user [rucalgary] decided to go the inkjet route instead, and picked up an Epson printer on clearance at his local electronics shop. This method is not new by any means, but his printer conversion is one of the simplest we’ve seen as it does not rely on any additional sensors to function.

Once he got home, he tore the printer down immediately, removing the paper input and output trays as well as the scanner bed. After all of the extraneous parts were removed, he got to work raising up the printer head, as well as the printer head rest mechanism. He mentions that the latter component is absolutely crucial to proper functionality down the line. Once the print head and its associated components were relocated, he added a pair of aluminum rails for feeding his print tray into the machine.

With everything complete, he filled up a spare cartridge with ink (he says that MISPRO yellow works best) and ran some test boards through. He is quite pleased with how things turned out, and is more than happy to give you a quick tour of his completed printer via the video below.

Continue reading “Direct to PCB resist printing requires minimal additional components”