Lightsaber lets you pick just about any ‘blade’ color

If you’re staging some epic Star Wars battles you could go original with Red or Blue lightsabers. But what if you decide you’re more of a fan of Jedi and want to go green? Or perhaps the prequels have inspired you to take on purple? Why choose at build time when you can adjust the color to match your mood.

[Phik] built himself a color-selectable lightsaber using RGB LEDs. He sourced a 5M strip of them from eBay for around $20. The pixels are not individually addressable, but each color channel can be driven with a pulse-width modulation signal to mix and match the final color. Now he could have gone with a microcontroller solution, but [Phik] decided to give himself a bit more of a challenge. He built three PWM circuits based on a 555 timer which can be adjusted with a potentiometer. It’s not going to kill any insects, but the keep-it-simple-stupid aspect of the project makes it something we could actually build ourselves. The same cannot be said for most of the replica builds we see.

555 business card

After checking out a few beautiful business cards while working at his engineering co-op, [Cody] realized he would soon need his own. Instead of a card with subtle off-white coloring, a tasteful thickness to it, and even a watermark, [Cody] decided to make a 555 timer business card.

[Cody] started his business card project by going through a few design iterations while figuring out what he wanted his business card to do. There were a few designs not chosen – one with a microcontroller, a few with just LEDs, and some with no circuitry at all. After checking out a few project from the EEV blog 555 contest, [Cody] decided to go with a simple 555 timer circuit.

Being a business card, [Cody] kept the circuit very simple; it’s just a 555, phototransistor, and a few SMD LEDs. When a 9 Volt battery is placed on the contact points of the card, the 555 lights up the LEDs. When a laser is shone on the phototransistor, the LEDs start blinking. A very neat and sufficiently interactive circuit that is perfect for keeping component costs down.

After the break you can check out [Cody]‘s business card in action.

[Read more...]

Auto power circuit for an arcade machine

Some of the pinball machines which [Jeri Ellsworth] has restored have ended up in the break room at her work. We’re sure her coworkers are thankful for this, but sometimes they forget to turn off the power to the machines, and letting them run constantly means more frequent servicing will be necessary. She set out to fix the situation by building a circuit that will automatically power the machines.

We think the solution adds some much needed functionality. Instead of hunting for the power switch, you can now power the machine up by hitting the left flipper, and it will automatically shut off after about five minutes of not having that flipper button pressed. For this she grabbed a 555 timer chip and built a circuit to control the relay switching the mains power.

She added a magnet and reed switch to the left flipper switch assembly to control her add-on circuit. It connects to the base of a PNP transistor which controls a resistor network and capacitor. This part of the circuit (seen to the left of the 555 in the schematic) allows the timer to be re-triggered. That is, every time you press the flipper the 555 will reset the timer. Don’t miss the demo she filmed after the break.

[Read more...]

Using 555 timers to add “free play” functionality to classic arcade machines

freeplay-arcade-board

[John Zitterkopf] is in the middle of restoring a vintage Sega Star Trek Captain’s Chair arcade game for the upcoming 2012 Texas Pinball festival, though one prerequisite for the show is that the game supports some sort of free play mode. At this point he doesn’t have the option of tracking down a freeplay ROM for the device, so he had to come up with a solution of his own.

He did not want to alter the machine’s operation in any significant manner, and this meant preserving the functionality of the coin chutes. To do this, he put together a small circuit that uses a pair of cascaded 555 timers to provide the machine with the proper signaling to simulate coin insertion, while still accepting coins. You might initially think that this could be easily accomplished by shorting a pair of contacts in the coin chutes, but as [John] explains, the process is a tad more complex than that.

If you have some old arcade games kicking around and are looking for a non-invasive way to make them free to play, be sure to check out his site for schematics and a complete BoM.

Building a computer out of 555 chips

[M. Eric Carr] came up with an interesting build for the 555 contest earlier this year, and we’re pretty sure that it would have kicked the winner of the complex category off the throne if it were completed. Although it’s a few months late, we’re happy to feature at least part of his 555-based computer on Hack A Day.

[Read more...]

Building a stepper driver

[TBJ] is building what he calls a junkbox 3D printer. You can probably guess that he’s trying to salvage most of the parts for the device, and after pulling a stepper motor from an old printer he was in need of a way to control it. What he came up with is a stepper driver that uses discrete components that are easy to acquire and inexpensive. The design calls for two inputs, one that toggles the direction in which the motor will spin, and the other that triggers one step of the motor. A CD4013 dual flip-flop takes care of both of these inputs in one chip package.

The motor is driven by a pair of H-bridges that he built using six transistors each. The trick with a stepper motor is that you need to drive the four poles of the motor to a specific logic level at a specific time. For this [TBJ] uses a CD4017 decade counter. A network of diodes grounds half of the output lines based on the flip-flop that controls direction. Our friend the 555 timer provides a clock for the circuit, keeping everything moving at a predefined rate. Check out the video after the break for an explanation and demonstration.

[Read more...]

Gigantic 555 footstool

The team at Evil Mad Scientist Laboratories needed a footstool. Obviously not content with buying one, they came across the idea of building a 555 footstool.

After finding some dimension drawings of the 555 timer IC, the team scaled everything up 30 times. While a normal DIP-8 555 is around 0.4 inches long, the footstool is over a foot long and eight inches high. The stool was cut on a CNC mill out of 1/2″ plywood, glued together, and finally panted with the correct date code and the logo of Evil Mad Scientist Labs. The finished product is amazing. We’ve been looking for a nice table, and the idea of an 8 foot long wooden 64-pin Motorola 68000 is pretty appealing.

While there’s no electronics in the footstool, it’s not hard to imagine fabricating some aluminum pins and a hollow body so a huge, functional 555 could be built. It would be possible to use discreet components following the block diagram of the 555 to build a huge Atari Punk Console; the gigantic capacitors are fairly easy to build in any event.