Rob writes in… [via]
I’ve seen quite a few hacks related to controlling appliances, lights, etc over the years and just wanted to share a little info so that everyone has access to a cheap way to do it relatively safely. By trade I work in the building controls/integration industry and as a result I use these relays at work and at home(chicken coop control,light,etc)quite a bit.
The interface between your microcontroller of choice and the relay is a simple 555 relay driver circuit. I have included the pdf that inspired me to do it this way. The relay I use is the RIBTU1C. The reason I prefer this relay is that the coil will run on 9VC @ 20mA and the contacts will switch 10A @ 120VAC. Total cost for the RIB and a 555 is under $15 if you shop around. In addition the RIB has a partition inside the box between the line and control sides. There’s also room for a Radio Shack breadboard in there!
Safety First! Switching 120vac loads with a microcontroller - [Link]
Something that a project that I’m working on has me doing is using a serial to parallel IC (think 74HC595) to control leds. However, rather than drive the leds directly from the pins, I opted for the use of transistors. After testing this out, it became apparent to me that perhaps the leds might be too bright, so I went in search of a simple PWM generator.
Yet Another Simple Pot-controlled 555 PWM generator – [Link]
Valentin B — 555 Inductivity Meter
555 Contest Winners Announced – [Link]
dangerousprototypes.com writes: [via]
What’s in a name? David L. Jones of EEVBlog thinks he’s found an Easter egg in the performance characteristics of the 555 timer chip which reveals the basis of the “555″ in its name. Build his circuit (schematic at video 13:25), fire up the scope and see if you agree!
555 timer Easter egg? - [Link]
I needed a variable slow speed clock to help me debug a design I’m creating with a bunch of CPLDs. Given the current focus on the venerable 555 timer IC, I thought rather than using my usual AVR/PIC solution I’d create something with the handy little timer.
555 based FPGA/CPLD debugging oscillator - [Link]
A music synthesizer is Frank’s entry to the 555 contest. He used a 555 timer to make a really cool synthesizer that is played with a stylus and has filtering and volume enveloping features. Various note frequencies are generated with precisely calculated resistances. [via]
555 Contest Entry: Music synthesizer – [Link]
Jim Chen made a very interesting LED chasing game that uses six 556 timer chips. This is his second entry to the 555 contest which is recently closed. There are nine LEDs in the game. Any of them could glow randomly. The player has to turn off the LED by touching an electrode next to the LED. While the player continue playing the game the time available for the player is less and less. When you missed to turn off an LED within the provided time frame, the game is over. Here’s how the game works. [via]
555 Contest Entry: “Whack a Mole” style game – [Link]
Direct conversion RF receivers are different from the standard superheterodyne one as they don’t have IF stage, and so the radio signals are directly converted into audio signals. This project uses 3 555 timer ICs as the only active devices to construct a direct-conversion radio receiver for the 80 meter amateur radio band. [via]
555 Contest Entry: Direct conversion RF receiver for 80 meter amateur band - [Link]
Really impressed by the turnout for the 555 Contest… something like 238 entries! The above videos show three of the submissions. [via]
Jeri and I are hard at work thinning the pack to pass on to our hack-master judges by next week. And don’t worry, even if you didn’t make the first cut, you’ll still be eligible for some of the door prizes from our wonderful sponsors. We’ll be announcing those judges soon.
In the meantime, I wanted to highlight only a few of the amazing projects we’ve already seen. Why should the aggregator sites get all the fun? We’ll be posting links to all of the entries in the coming days, once the entries have advanced to the next round. Check out 3 videos Jeri and I thought were particularly fun and inventive.
555 Contest Entries Already Wowing the Organizers – [Link]