USBasp: AVR programmer based on ATmega8

We love our AVR Dragon programmer but it can be nice to have a cheap and simple in system programmer on hand too. The USBasp is one such programmer that uses and ATmega8 as its only IC. It requires just a handful of components and can be purchased as a kit, or etched and assembled at home. If you source your own parts the chip does need to be programmed which makes for a chicken-or-egg scenario. We’ve used the Parallel-port dongle (schematic) from Adafruit’s Spoke POV before. It’s basically just a DAPA cable and a few resistors, a ribbon cable (use and old IDE cable if you have to) and a parallel port connector can have you up and running in no time. This is also a great way to get a friend into working with embedded systems. Order parts for a few of these and give them away to your buddies.

Nixie-display brings more wiring madness

[Tim Anderson] whipped up this nixie tube display using epoxy-coated wires. He’s certainly giving the wire-wrapped LED display a run for its money. He ground the epoxy off the end of each wire using a Dremel before soldering them. We thought you could solder right through the epoxy but maybe not. Was this easier than wire wrapping would have been? We’d bet that because of the voltages wire wrapping wasn’t an option here. That board on the left is the 180V power supply for the tubes with an AVR chip running the Arduino bootloader to the right. After the break there’s a brief demo of data being pulled down over a serial connection. [Tim] also has some plans to add an atomic clock module to this setup sometime down the road.

Wire-wrapping an LED matrix

Regular reader [Osgeld] built a 1024 LED display matrix. This is a proof-of-concept design and he admittedly has overloaded the components. Most notably, the 595 shift registers (featured over the weekend) are sourcing too much current if all eight pins are active. That’s easy enough to fix in the next design by moving up to cascading LED drivers. Instead of soldering every connection in the display, [Osgeld] soldered the components in place and then used wire wrapping to make the point-to-point connections. This must have saved him a ton of time and frustration. We can’t wait to see what comes out of this first prototype.

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