Posted on Friday, April 16, 2010 • Category: PC Circuits
Using an add-on card to the already existing avr ethernet board we build a weather station. That is: A weather station with a build-in webserver.
My original plan was to have sensors for temperature, air pressure and wind. I started a prototype and it worked very well except for the wind measurement part. I plan to improve the wind measurement hardware and add it at a later point in time.
Posted on Friday, April 16, 2010 • Category: LED
In many cases can be very handy to be able to convert 1.5V to 5V. Then you can power microcontroller or LED from a single AA or AAA battery. It is simple to do this as there are special IC’s as MAXIM MAX1674 or MAX7176. This is step-up DC-DC converter that can convert voltages from 0.7V to any in range from 2V to 5.5V. MAX1676 have already preset pins for 3.3V and 5V, that makes easer integration in 3.3 and 5V circuits. IC can dissipate up to 444mW.
Bellow is a circuit that converts 1.5V to 5V.
Posted on Friday, April 16, 2010 • Category: USB Circuts
With serial and parallel ports being phased out on new computers, hardware designers and hobbyists have no choice but to convert the USB port back to RS232 serial. FTDI have a very nice chip that does just that, the FT232AM. This chip converts USB to a standard high-speed serial port. The bonus with FTDI is the drivers are already written for you. All you have to do is design the hardware and download the serial USB drivers from FTDI's web site.
Posted on Friday, April 16, 2010 • Category: Battery Chargers
This is a NiCd/Ni-MH charger that can charge with constant current and automatic charge termination when the total voltage for all cells reach the setting voltage.
Posted on Friday, April 16, 2010 • Category: PIC
This project is based on ideas from Rickard's electronic projects page and David B. Thomas VCR Pong. However, I have developed the simplicity even further, eliminating most of the external components. Using microcontrollers with internal 4MHz clock generator there is no need for the xtal. The 12f675 part also operates on wide voltage range, and the regulator can be removed.
For game controller, I plan on using the old Commodore 64 style paddless. They include firing buttons, which I plan on using as power switch and game reset. 16F675 has a low power sleep mode with 1nA current consumption, so I plan on using that to switch off.
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