Extending The Battery Life Of LED Dominoes

April 26, 2011 by Mike Szczys 6 Comments

[Fede.tft] wrote in to tell us about some work he’s been doing to save battery life for LED dominoes. He originally got the idea after reading this post about the electronic gaming pieces. That project was aimed at the 555 timer contest and therefore, used a 555 timer. [Fede.tft] calculates the battery life for the CR2302 battery in the 555 circuit at no more than about 80 days. That’s if you never use them and the LEDs are never illuminated. It makes sense to remove the batteries from the device when not in use, but a redesign to increase efficiency is definitely worth the effort.

This rendition does away with the 555 chip in favor of a CMOS chip. By building a circuit around four NAND gates of a CD4011 chip, the standby lifetime of the battery is calculated to increase to about 4.5 years. Not bad! Add to this the fact that replacing the 555 timer didn’t increase the component count, the price for the chip is similar to the 555, and you didn’t need to resort to a microcontroller. Yep, we like it.

IR Remote Control Jammer Makes You Lord Of The Livingroom

April 7, 2011 by Mike Szczys 13 Comments

Bring communications jamming technology into your TV viewing experience by building this infrared LED driver circuit. You’re probably familiar with the TV-B-Gone, which let’s you turn off any television at the touch of a button. But what if you actually want to watch the program that’s currently on the screen when the person with remote-in-hand doesn’t? That’s where this little marvel comes in.

[KipKay’s] IR jammer uses a 555 timer to constantly transmit infrared traffic. The signals it’s sending out don’t correspond to commands the TV (or any other IR remote-controlled device) will respond to. But if the light intensity is strong enough, they will interfere with any signals coming in from a remote or even from a TV-B-Gone. [KipKay] wisely hides this circuit inside of another remote control so that the other couch potatoes you are thwarting won’t get wise to what’s happening. If they want to watch something else they’ll have to get up and walk over to the entertainment center to do something about it, and what’s the chance that’s going to happen?

Don’t miss [KipKay’s] infomercial-esque presentation of this gadget after the break.

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Freedombot Explores Your Fridge

March 21, 2011 by Chris Nelson 10 Comments

Freedombot is a neat little robot designed for exploring magnetic surfaces. It has two whiskers for detecting objects in its path and two rare earth magnets which allow it to stick to your fridge.

Overall Freedombot may not be anything revolutionary but its builder [skater_j10] does a good job of covering topics which my be interesting to robotics beginners. For example he goes through the process of modifying some HiTec HS- 55 Micro Servos for continuous rotation which allows them to act as the wheels. To control the bot he uses two 555 timers wired up in astable mode to generate the needed PWM for the servos. The proximity sensors are simple limit switches with some wire soldered on to the end. The end result is a neat little robot for roaming the front of your fridge. See a video of it in action after the break.

This happens to be [skater_j10]’s entry into the 555 timer contest. Unfortunately the deadline has passed for new entries but be sure to swing by and check out some more awesome 555 hacking.

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ASync-Firefly

March 11, 2011 by Noah Dunker 8 Comments

[dev_dsp] wanted to try his hand at creating a purely analog implementation of multiple synchronizing fireflies powered by a single battery and built from off-the shelf, through-hole components on inexpensive protoboard. In theory, even your local Radio Shack should still carry all of this stuff. He was obviously inspired by [alex]’s fireflies that we’ve covered in the past, but he wanted to see how far it could be taken without the use of a microprocessor.

In the end, [dev_dsp] relied on one crucial piece of digital ware, the ever-popular 555 timer IC, but he’s using analog discrete components to do the grunt work of adjusting the phase of each firefly by feeding a little extra current to the trigger capacitor whenever the flash of a nearby firefly is detected. After the jump, you’ll find schematics and a video demo of three ASync-Firefly modules in various stages of assembly playing with one another while [dev_dsp] discusses their operation.

A 555 Synthesizer

March 9, 2011 by Kevin Dady 12 Comments

Inspired by the memory of a childhood electronics kit, [Frank] decided to make a new 555 Synthesizer and enter it into the 555 contest. [Frank’s] remake is played with a stylus, and sports an attack and release envelope circuit, housed in a quick but effective acrylic case.

Using a single 555 timer, a hand full of capacitors, two transistors, and a healthy dose of resistors and potentiometers, the sound is quite impressive thanks to optional filtering, enveloping, and a lot of fine tuning. Full schematics, bill of materials, formulas, and board files are all available along with sources for some of the more specialized potentiometers.

Join us after the break for a ~13 minute long video, which is pretty cool, as it shows the device from prototype, and does some fast forward action though to the final product pictured above, though if you just want a demo of the 555 synth fast forward to 10:44

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Keypad Input Scanning By A 555 Timer

March 3, 2011 by Mike Szczys 17 Comments

[R-B] designed a 555 timer circuit to scan a keypad. Keypads are common interfaces for small projects and require row and column scanning by a microcontroller. [R-B’s] setup allows you to reduce the number of pins used on the microcontroller to just two. One is an interrupt that is triggered when any of the buttons are pushed, the other reads the frequency from the 555 chip. Each button has its own resistance which alters the frequency of the 555. The microcontroller reads the frequency for 100ms using a timer. The number of timer overflows that occur during that period directly correspond to the button press (five overflows for the numeral 5, zero overflows for the numeral zero).

We usually debounce our button presses for 40 ms, this is more than twice that amount of time but still not a staggering difference. It does make us wonder if you will miss quick button presses? The only really way to know is to try this out yourself. Check out the video after the break and don’t forget to leave a comment with your own experiences in working with the circuit.

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Earthquake Alert System

March 2, 2011 by Mike Szczys 15 Comments

[Roteno’s] submission for the 555 timer design contest is an Internet connected earthquake alert system. It monitors the USGS website for earthquake data and plays a tune when an earthquake occurs. The data is available as a feed in the form of a TXT file which is pretty easy to parse using cURL. He chose an LPCXpresso board (which is an ARM development platform that can run a Linux kernel) along with an XPORT module to handle the Ethernet traffic.

So where does the 555 timer see some action? It is responsible for playing the tone when an earthquake is detected. But playing just one pitch isn’t much fun. Instead, [Roteno] built the circuit above which creates a resistor network switched by a series of transistors. This way he can use GPIO from the microcontroller to choose different pitches. Check out the video after the break to hear the results. At power-up all eight pitches are played as a test, and the alert sound varies in pitch and tempo based on the magnitude of the earthquake.

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