[Bill Zimmerman] is in Cameroon and has been posting some really interesting articles about life in the central African nation. It comes as no surprise that imported goods can be prohibitively expensive for many of the country’s residents, so building tools and goods is way to improve life and save money. The image above is a metalworking cooperative where any number of products are manufactured from recycled materials, often using tools that the craftsmen made themselves. Their wares are amazingly wide-ranging; crow bars, motorcycle seats, buckets, plows, hammers, knives, cold chisels, and much more. The video after the break shows the tradesmen hard at work. See some video of the cooperative after the break.
But adults aren’t the only ones getting in on the action. Remember [William Kamkwamba] who built a wind generator for his villiage? It seems the tinkering spirit runs deep in the children of Cameroon as well. [Bill] came across some kids who grabbed leftovers like the soles of sandals, scraps of rope, and empty sardine tins to build a steerable toy car.
[74hc595] just finished his entry in the 7400 logic contest. It’s a drum machine built entirely from 7400-series logic chips. He hasn’t quite reached full completion of the project yet. The hardware works just fine, and he’s built a foam core face plate with many more controls than you see here but much of the circuit is still on a breadboard at this point and only two of the channels have been complete thus far.
Jump to the video clip after the break to get the details of how the system works and to hear it in action. This demonstration is one of the best we’ve seen for a synthesizer project as he actually talks about what each control does, and how that is accomplished with the hardware. We’re not going to go into detail about the circuitry he’s designed. As we said before, it uses 7400 logic but also sources a 555 timer to keep the beat. The page linked above has a PDF of the schematic available and you could really lose a lot of time studying how he did this. We might even try to build it in a simulator to see what we can learn.
Continue reading “7400 drum machine is a delight”
We can order seven segment displays in red, green, yellow, or blue all day long. One thing we haven’t seen is an RGB segmented display, so [Markus]’ project is really interesting. He took a stock seven segment display and modded it into an RGB display.
After taking a Dremel to the back of the stock display, [Markus] was left with a seven segment light mask. A few SMD LEDs were purchased through the usual channels. The RGB LEDs were epoxied into place on the back of the light mask one at a time. Thankfully, the LEDs came with magnet wire already attached – helpful, since these LEDs are only 1.6mm x 1.2mm big.
With 32 pieces of magnet wire, [Markus] needed some sort of socket. A small piece of perfboard and some .100″ headers handled the job very nicely. [Markus] still has to work on some way to drive the 24 cathode lines his LED display. He’d like an I2C interface, but with something like an individual seven segment display, the footprint of the circuit should be pretty small. If you’ve got any tips, drop them in the comments section. [Markus] is sure to catch them there.