Kennith needed a 1A constant current lead-acid battery charger for his HAM radios so he writes:
Since the SLAs are relatively small, and I only need them charged between radio outings, I opted to build a 1A constant current charger, based on the 555 Battery Charger which won first place in the 555 Design Contest Utility category. Using a 555 is a rather clever way to get two comparators and a Set-Reset latch in a single 8DIP package, which is needed for the high and low trip points. The major difference between my design and Mike’s is that instead of using a relay like him, I use an LM317 as a constant current source to limit my batteries charge rate.
555 based constant current lead-acid battery charger - [Link]
This project is an all-digital-hardware LED Christmas tree we’re calling the Christmas Tree O’Digital Logic. The tree itself is composed of 64 LEDs built into a spiral sitting on a piece of protoboard. Underneath, the controller uses shift registers and a 555 timer to create two modes of display: a predictable pattern and a random pattern. This should light up any desk or shelf and bring merriment to you.
Christmas Tree O’Digital Logic - [Link]
This is an all-digital-hardware Theremin. The Digital IR Theremin uses comparators, digital logic and a single 555 timer for tone generation to make it so that when you wave your hand in front of the infrared proximity sensor, it outputs a tone with varying pitch depending on how far away your hand is from the sensor!
Digital IR Theremin - [Link]
Last month one of the unsung heroes of electronics has passed away. Hans Camenzind, father of one of the most famous integrated circuit of all times, the Signetics timer NE555, timed out at the age of 78. Being a gifted analog designer, Swiss-born Monsieur Camenzind is also credited to be the father of class-D amplifiers and he has introduced the concept of the Phase-Locked Loop (PLL) in ICs. During his rather productive career he designed over 140 ICs, wrote several books and many articles and his name is attached to some twenty patents.
When a famous artists dies you will hear his or her greatest hits on every radio or see his or her best films on every TV channel. Therefore, in respect of one of the great electronics inventors of our century we will play here Hans Camenzind’s most successful composition, NE555 in bipolar. [via]
Hans Camenzind, father of the NE555, dies at the age of 78 - [Link]
This GM-Counter is build on 2 PCB’s. One is a standard high Voltage generating circuit, whilst the second is a Counter based on an ATMega16™ which also handles serial Communication with a host (Environmental Control).
The High Voltage generator is based on a 100 Hz Chopper, which is build around a ’555′ in combination with a standard Transformer and a Cascade to achieve Voltages from 400 to approx 900 V. (adjustable) The Regulation is just on-off (Burst) which will result in approx 1% Drift. This Circuit consumes about 20 mA at a 9 V (Battery). (more when starting up
Homebrew Geiger Müller Counter - [Link]
Here is a rather simple but practical use for digital electronics…..dice! (or in the case a single die)
Unlike many of the kits found online this one does not use a micro controller. The entire circuit is based around 74LSxx logic ICs and a 555 timer for a clock.
7400 competition entry: Digital die (74XX Family) - [Link]
Arup wrote a guest post about his Nokia LCD breakout board:
I designed a simple Nokia LCD Breakout board which allows you to interface any Nokia 6100 compatible display to microcontroller like PIC and AVR. The board itself provides 6.8volts for the backlight by a simple boost converter built up using a common 555 timer IC. There’s a switch to choose whether you want to work with 5V logic, or with 3.3V logic. [via]
Simple Nokia LCD breakout board - [Link]
Giorgos Lazaridis writes:
Some time ago i uploaded a breathing LED circuit with the 555 timer chip. It became very popular and i received many comments and emails with people that made this circuit and worked fine, as well as comments with people that had troubles converting it to operate at 12 volts supply. It was designed to operate with 5 volts, because i plan to use it for a future PC mod. Since the PC power supply has 5 volts output, and since the LEDs that i plan to use require 3.8 volts to operate, choosing 5 volts for supply was the best choice to minimize power dissipation on the transistor.
Converting the original circuit to operate at 12 volts is not a big deal, but it requires some transistor knowledge. The only parts that should be changed were the biasing resistors R4 and R5. But i decided to take it one step further. I decided to make a more flexible breathing circuit. The new version as 2 more functions: It has an adjustable voltage oscillation amplitude, and an adjustable output DC offset. What this means is that it can be easily adjusted to operate with different LEDs. If for example the load is a 12V LED strip with operating voltage range 8 to 12 volts, the circuit can be adjusted to provide exactly this: 8 to 12 volts output. Similarly, it can be adjusted to operate with a high brightness LED that has voltage range from 2.4 to 3.8 volts.
Flexible 555 LED Pulsing (Breathing) Circuit - [Link]
Giorgos Lazaridis writes:
During this very long period that my PC went bad, i had the time to do many thing like finishing the PC case mod that i began like two years ago… So i connected the power button, the reset button and the audio controls. The rotary encoder will be used for my next project that will be a gigantic scriptable 8-channel PC fan controller.
Now, regarding the power button, it has a blue LED that light when the HDDs are operating (write or read process). The effect is very cool, but i want to make it cooler. I want the LED to blink when the HDDs are used, and when no Read/Write operation occurs i want the LED to breath. A breathing LED is the effect that the LED turns on and off by fading in and fading out, which gives the feeling of “breathing”…
A 555 Breathing (Pulsing) LED - [Link]
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]