Building A UV Exposure Box

October 20, 2010 by Mike Szczys 29 Comments

There are two methods of using etchant resist when making circuit boards. We use the toner transfer method that requires ironing on laser toner to the copper, but you can also use chemical resist that reacts to ultraviolet light. [Bogdan] decided to start doing more of the latter so he built a UV exposure box to make the process easier.

It is possible to use flourescent light bulbs for this, but he decided to use UV LEDs, a method we’ve also seen before. But there’s always room to innovate, and [Bogdan] built-in a couple of nice features that are new to us. Because the UV light can be bad for your eyes, he included a set of red visible-light LEDs on the bottom half of the box that are used to align two layers of exposure mask when making double-sided boards. There’s also a switch that automatically shuts off the UV light when the box is opened. And as the coup-de-grace, he added a programmable timer to regulate the exposure, using his newly created box when etching the PCB for it.

3D Printing With Visible Light

October 15, 2010 by Mike Szczys 14 Comments

This 3D printer manages some pretty fantastic resolution, and these are just the early results of [Junior Veloso’s] build. He put together a machine that prints objects in resin that cures in visible light. To print, a thin layer of raw liquid resin self-levels across a printing surface and a DLP-based projector shines light from below, onto the portion to be hardened. The z-axis then pulls that layer up and the next to be printed will become the newest bottom layer. Horizontally the printer yields 1024×768 resolution with a layer thickness as small as 0.01 mm. No wonder he’s turning out this kind of quality.

The model above took 5 hours to print, with eight-second exposure for each layer, and 0.1mm layer thickness. There is lots of good information on his blog, from the early planning, to the finished hardware so take some time to learn about this fascinating project.

Update: Thanks to reader [Nave.notnilc] for pointing out that we’ve seen a chemical 3D printing technique before.

Bench Supply With Current Limiting

October 8, 2010 by Mike Szczys 14 Comments

This is a bench power supply with adjustable voltage and current limiting. [Sylvain’s] creation can regulate 0-25 volts while sourcing 0-5 amps. Current limiting is a nice feature as it will allow you to test your prototypes to ensure the power regulator you choose will not be over or underpowered.

This supply is really a two-in-one. The case has two separate circuits so that you can have different power rails going at the same time. There is a microcontroller involved, but the ATmega32 doesn’t do anything more than measure the voltage and amperage and drive the graphic LCD screen. Two potentiometers are responsible for setting the voltage and limiting the current.

[Thanks Sargonout]

PIC Programmable Power Supply

October 6, 2010 by Mike Szczys 17 Comments

This programmable power supply is the perfect addition to your bench tools. [Debraj Deb], who previously built a whole house power monitor, designed this build around a PIC 18F4520 microcontroller. The desired voltage is set with an attached keypad, resulting in a digital output on the 8-bits of port D. The port connects to another protoboard with an R-2R digital-to-analog converter resulting in the target voltage. A set of transistors amplifies the current and a power transistor then takes care of the final output. After the break you’ll find two videos, the first walks us through the hardware and the second demonstrates the device in action, along with measurements of its performance. This certainly provides a lot more functionality than an ATX power-supply conversion.

Update: A big thanks to [Debraj] who sent us a code package as well as the schematic (PDF) used during testing. We’re having trouble getting the code package up for download right now. Check back later, hopefully we’ll have it up soon.

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Solder Paste How-to Tutorial

September 28, 2010 by James Munns 15 Comments

The application of Solder Paste is an essential part of short run manufacturing and prototyping. After getting back bare boards from a PCB shop, its time to get down to business and populate those boards. This new tutorial set assumes you have access to things such as stencils for your boards, but does mention a couple of resources on commercially available ways to purchase stencils. Of course, if you have a laser cutter, we can help you out. After getting your solder paste chops down, make sure you check out our guide to toaster oven reflowing.

[Thanks to P. Torrone]

Beefing Up A Cheap Drill Motor

September 20, 2010 by Mike Szczys 18 Comments

[Rob] just finished reinforcing a cheap drill motor. He picked up the tool at Harbor Freight and ditched the case. The plastic retaining ring was replaced with a thick metal washer which he machine The washer uses three bolts to attach to the mounting plate that he welded together. We’re not exactly sure what he’s got in mind as he only mentioned that this will be used with a robot. We wouldn’t mind having one of these as a bench motor but there must be hundreds of uses now that it can be attached to just about anything. It seems Harbor Freight has become popular as hacking’s raw material source. The last example we saw of this was a welding table made from a utility cart.

PVC Pipe Fittings Just For Building Stuff

September 10, 2010 by Mike Szczys 50 Comments

If you’ve used PVC as a building material in your projects you may have run into trouble finding a way to make three pipes joint at right angles to each other (like the corner of a box outline). That’s because there’s no need for that type of joint when plumbing, the intended purpose of the PVC pipes. But [John] tipped us off about FORMUFIT PVC Fittings designed for construction use instead of plumbing. There’s a lot of interesting options, such as the ninety degree connectors, rounded end caps for aesthetics, and end caps designed to receive casters. We also enjoyed seeing the T connector that slides onto a pipe and can function as a swivel. We haven’t tried them out ourselves, but we think they’d come in hand whether you’re building complicated moving structures or just making a desk.