When working with microcontrollers that require a factory calibrated osccal value stored in memory, it’s very normal that once in a while this setting could be lost during an upload of a new program or when accidentally erasing the device.
I’m no exception and erased many times this value by mistake in several devices. Once this value is erased, it’s not possible to recover it unless it was written on a sheet of paper or in our own memory and use it to record it back.
This project has the ability to calculate what is the appropriate osccal value for the 12F675 microcontroller.
OSCCAL Value Finder – [Link]
The DrinkShield is an open source Breathalyzer kit for the Arduino. The DrinkShield can work as a standalone breathalyzer or you can connect it to a computer for and interact directly with the results. Source code repository comes with a game to use as a proof-of-concept.
DrinkShield for Arduino – [Link]
IR detectors are little microchips with a photocell that are tuned to listen to infrared light. They are almost always used for remote control detection – every TV and DVD player has one of these in the front to listen for the IR signal from the clicker. Inside the remote control is a matching IR LED, which emits IR pulses to tell the TV to turn on, off or change channels. IR light is not visible to the human eye, which means it takes a little more work to test a setup.
In this tutorial we will show how to:
Test your IR sensor to make sure its working
Read raw IR codes into a microcontroller
Create a camera intervalometer
Listen for ‘commands’ from a remote control on your microcontroller
IR remote receiver-decoder tutorial - [Link]
Rudolf Moers from the Netherlands has kindly sent us details of his parallel push-pull 300B monoblock tube amplifiers to share with the DIY Audio community. It should be quite obvious from the photographs that the design and construction of a pair of amplifiers this size is by no means a small undertaking. Rudolf tells us that he spent about 14 months designing and constructing the pair of monoblock amplifiers. The total cost of each amplifiers was about 1300 Euro, or about $1760US as of 29 September 2010. Each monoblock weighs 25 kg (55 pounds) and the overall dimensions are 530 mm deep, 390 mm high, 400 mm wide.
Parallel Push-Pull 300B Tube Amplifiers - [Link]
This is a digital voltmeter project that uses PIC12F683 to measure the input voltage and displays it on LCD. It uses a resistor divider network to measure input voltage ranging from 0-20V. Full 10-bit resolution is used for internal ADC for higher accuracy. The firmware is written in mikroC and available for free.
0-20V Digital Voltmeter using PIC12F683 - [Link]
PIC Voltmeter Amperemeter can measure voltage 0-70V or 0-500V with 100mV resolution and current consumption 0-10A or more with 10mA resolution. The meter is a perfect addition to any power supply, battery chargers and other electronic projects where voltage and current must be monitored. The meter uses PIC16F876A microcontroller with built-in ADC (Analog to Digital Converter) and 16×2 green backlighted LCD display. With slight modification it is possible to measure higher voltage and current.
PIC Volt Ampere Meter – [Link]
This project shows how to build a data logger for humidity and temperature using the SHT11 or SHT15 sensor. This is a full digital sensor connected to AT90S8535 AVR microcontroller.
SHT11: Digital Temperature and Humidity Sensor - [Link]
This circuit is an audio amplifier circuit rated at 25W. It uses IC number LM1875, which is under the protection circuit IC output or Too short circuit and a significant distortion as low as 0.015% at a frequency of 1kHz.
25W Hi-Fi Audio Amplifier using ic LM1875 – [Link]
V-USB is a software-only implementation of a low-speed USB device for Atmel’s AVR® microcontrollers, making it possible to build USB hardware with almost any AVR® microcontroller, not requiring any additional chip.
V-USB: A Firmware-Only USB Driver for Atmel AVR Microcontrollers – [Link]
Kicad is an open source (GPL) software for the creation of electronic schematic diagrams and printed circuit board artwork. On the site below you can find two video tutorials on how to use the schematic editor and how to make a new PCB. Check the videos on the link below.
Kicad open source schematic and PCB software – [Link]