Giorgos @ pcbheaven.com faced a problem when he tryed to use his PIC 3-Wire Fan RPM Controller to control a Zalman fan. The problem was that the fan couldn’t work on low RPM without stalling …so he devided to move a step further and try “Pulse Stretch method”. Investigating the problem found that the internal tacho didn’t powered correctly at low PWM. This problem solved by turning PWM to 100% for some time during normal operation, allowing the microcontroller to read the tacho value. Another great feature of this method is that when the fan is stalled PWM goes 100% allowing the fan to resume proper operation… That’s a really interesting method…. read details of this method on the link below.
PWM 3-Wires Fan Controller with RPM feedback - [Link]
We present another great project of Giorgos @ pcbheaven.com, that’s a PC System Health Monitor. He build this project to control the fan speed of his PC-Box and to monitor temperature on various check points. There is a separate control module on each fan. In that way each fan has each own address and can be monitored independed. Check out this nice project on the link below.
PC System Health Monitor - [Link]
MarkusB @ letsmakerobots.com desinged a simple Geiger counter using 555 timer ICs, some transistors, capacitors and resistors. Circuit is powered from 5V source and the necesery high voltage is generated via a capacitor-diode charge pump. When ionizing radiation hit the Geiger tube a short pulse is generated at the output. In that way the output events rate indicate radiation activity intensity [via]
DIY Geiger counter using 555 - [Link]
OpenPICUS is a new module based on Microchip PIC 24F series with embedded wireless Stack and wireless module (bluetooth or Wi-Fi). This project is under actual development and the goal is to build the first OPEN wireless platform for sensors, infopoint and all the applications that needs to connect to mobile phones and Internet. Follow project development on openpicus.blogspot.com. They are planning to give free evaluation boards to those friends that will share ideas and suggests..
openPICUS project is born to let developers (hardware and software) create their advanced wireless sensor applications even without any hardware experience. We’d like to share and to create this platform based on a community to analize the user needs and the experts ideas.
Get more details on PICUS press release
OpenPICUS wireless platform project - [Link]
Giorgos @ pcbheaven.com build a PIC based thermometer and thermostar for his etching bath heater using a NTC thermistor… project description, schematics and code can be found on the link below.
PIC Thermometer and Thermostat - [Link]
Yenka Electronics is a design and simulation software that let you draw your circuits using over 150 different components and with the push of a button you make it working! You can desing analog and digital circuits, set maximum component ratings, desing PCB and even include PIC and PICAXE chips in your circuits. On the site below you can find a FREE copy to use it on home. Also, be sure to check other Yenka’s software, they design really interesing science, mathematics and technology training software.
Design and Simulate circuits using Yenka Electronics - [Link]
Propbot @ xtune.se is an autonomus line following robot that you can build your own using schematics and PCB available on the site below. Robot is based on Parallax propeller and it’s a good chance to learn about robotics.. On there site there is also available a assembled version of this robot.
Propbot: line following robot - [Link]
Josh @ imsolidstate.com describes how he converted a battery charger to spot welder. This spot welder has digital control circuit and current monitoring to precise control the welding procedure. Source code and schematics are available on the link below.
Build a spot welder from a battery charger - [Link]
The LM21305 is an adjustable frequency synchronous buck regulator capable of delivering up to 5A of continuous output current. Input voltage is 3V to 18V and output voltage is adjustable to range 0.6V to 5V. Switching frequency is also adjustable via a single resistor from 300 kHz to 1.5 MHz. Visit the link for more info / datasheet.
LM21305 – 5A Buck Regulator - [Link]