Building A Power Supply Around A DC-DC Converter

September 12, 2010 by Mike Szczys 15 Comments

The EEVblog is on a roll with interesting topics lately. In the latest episode [Dave] takes us through the nitty-gritty of switch mode power supply design. Using DC-DC converter IC’s in not especially hard. The datasheets tend to have fairly good usage schematics but there’s always a bit of heartache that goes into figuring out which external components will make for an optimal design. Get your calculator out and, in the video after the break, he’ll walk you through choosing component values based on the formulas for the MC34063 converter chip.

[Dave] makes the point that this is an extremely common chip, available from several manufacturers, and often found in consumer electronics. In fact, the switchmode supply hack from last month was using a regulator based around the MC34063. So you can buy it or scavenge for it. One thing to note though, we checked Mouser and Digikey and they’re pretty short on these chips right now. Plan your projects accordingly.

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Projectile Speed Sensor

September 7, 2010 by Mike Szczys 16 Comments

[Mike] built a sensor rig to measure projectile speed. The setup uses a tunnel with two sensors in it. Each consists of a laser diode on one side focused on a photodiode in the other. The two are monitored by an op amp and measured by an ATmega128 microcontroller. When the beams are broken the elapsed time between the two events is measured in order to calculate speed. There is a setting to adjust the calibration for a range of speeds, which came in quite handy as [Mike] initially tested the device with rubber bands before moving on to a pellet gun and then a rifle.

It seems like he’s tempting fate by shooting a target just a few inches below his exposed circuitry but his marksmanship prevailed. We’ve seen bullet speed detectors in the past, used just for the delight of seeing how fast the projectile is moving, and also to capture an impact at just the right instant.

Alarm Clock Learns New Trick, Opening Doors

September 1, 2010 by Jakob Griffith 21 Comments

Waking up at 5:30 in the morning. [Mark Stead] didn’t like the idea either when his chickens started crying to be let out. One simple solution obviously is to eat the chickens build an automatic door opener. The mechanism starts out with an old style mechanical alarm clock, add a geared motor with some creative switch work to pull open the door, weather proof the entire thing, and done. [Mark] even modified the setup later to work with vertical doors. No MCU required for either.

Pair this with an automated feeder system, egg gathering and cooking setup, and you’re half way to having your breakfast ready for you when you wake up in the morning – around noon like the rest of us.

[Thanks MS3FGX]

Art Piece From Board Artwork

August 29, 2010 by Mike Szczys 11 Comments

[Theo Kamecke] is an artist who produces striking pieces using printed circuit boards. We’ve seen PCBs used as faux stained-glass before, but [Theo’s] craftsmanship stands apart from everything we’ve seen. His webpage has at least one piece that sites the usage of vintage 1960’s circuit boards, but we wonder if he doesn’t design some of these to suit his work. Either way, we’d love to see him take on the finish work for that mechanized expanding round table we saw back in June. See more of his work on his photostream.

[Photo Credit]

[Thanks Mowcius]

Beginner Concepts: Analog Circuits

August 28, 2010 by Mike Szczys 38 Comments

We look at a lot of projects that have microcontrollers in them. That’s because microcontrollers do cool stuff, but there are still plenty of tricks you can pull off with analog circuits. [Osgeld’s] latest project explores this realm, controlling the discharge of capacitors through an LED. His setup uses just nine components and, if you’ve been collecting broken electronics from your friends and neighbors like a good hacker, you can scavenge all of these parts. Try it, you’ll like it!

RS232 And RS485 Networking – No Code Required

August 14, 2010 by Mike Szczys 21 Comments

Here’s a serial to Ethernet module that you won’t have to write firmware to build. It uses a Lantronix XPORT module which takes care of all the work for you, including an embedded webserver. Both RS232 and RS485 data buses are connected to the XPORT serial input via a level converter to step the signal down to 3.3V. This solution comes at a price because of the ethernet module, but it would make a nice prototyping tool for testing projects that work on the two serial protocols.

Airsoft Minigun Packs Quite A Punch

August 12, 2010 by Mike Szczys 34 Comments

[Kuba_T1000] built a multi-barrell Airsoft minigun with an unbelievable firing rate and an almost inexhaustible ammo pack. The gun is made entirely from aluminum which meant some time on the CNC machine. The six barrels don’t rotate but they are all used, resulting in the carnage shown in the video after the break. That large box you see is the ammo pack, which can hold 16,000 BBs and uses an electric feed system to reach the necessary delivery speeds. It is certainly not something you’d want to run into as part of an automated turret.

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