This DIY digital clock plus thermometer is designed by Joe Farr and is based on PIC18F25K22 microcontroller. The complete construction details of this project including circuit diagrams, PCB layouts and PIC firmware are posted in his website. He developed his firmware using Proton PIC BASIC compiler, which is available for download for free for this particular PIC microcontroller. He uses DS1302 RTC for timekeeping and DS18B20 for temperature measurement. The temperature and time are displayed on four 2″ seven segment LED displays.
Another PIC-based digital thermometer and clock - [Link]
Project is based on Holteks IC HT7610A, which is a CMOS LSI chip designed for use in automatic PIR lamp, flash or buzzer control. It can operate in 3-wire configuration for relay applications. In our project we have used relay instead of Traic to connect any kind of load in output, HT7610B IC is suitable for traic and HT7610A for Relay application. The chip is equipped with operational amplifiers, a comparator, timer, a zero crossing detector, control circuit, a voltage regulator, a system oscillator, and an output timing oscillator.
Its PIR sensor detects infrared power variations induced by the motion of a human body and transforms it to a voltage variation. If the PIR output voltage variation conforms to the criteria (refer to the functional description), the lamp is turned on with an adjustable duration. The circuit doesnt required step down transformer and can work directly by applying 110V AC or 220V AC (Capacitor C7 needs to change for 220V AC (0.33uF/275V) and 110V AC (0.68uF/275V)
PIR Sensor - [Link]
Here’s a pool cleaner robot built on ATmega by Davide Gironi:
My replacement electronics it is based on ATmega8 micros.
The project is divided into two parts:
The timer contains the 220 AC to low voltage DC current, and it is out of water, his purpose is to start and stop the cleaning pool robot, which of course is inside the swimming pool.
ATmega based pool cleaner robot - [Link]
Elia wrote an article detailing his binary wrist watch project:
I have just finished my binary wrist watch project (well, the new revision anyway). I was surprised at how small I was able to make it compared to last time.
I chose to go with the “super-yellow” color LEDs as they fit the purple OSHpark PCB very nicely. The biggest challenge was actually making a good looking wrist band for the watch. I originally intended to use a design like this but it turned out that due to lack of enough para cord I had left, I went with a simpler design that I had done once before.
DIY binary wrist watch - [Link]
Freescale have introduced a new range of 3-axis accelerometers offering high sensitivity at low power consumption. According to Freescale the FXLN83xxQ family is capable of detecting acceleration information often missed by less accurate sensors commonly used in consumer products such as smartphones and exercise activity monitors. In conjunction with appropriate software algorithms its improved sensitivity allows the new sensor to be used for equipment fault prognostication (for predictive maintenance), condition monitoring and medical tamper detection applications.
High sensitivity Accelerometer Family - [Link]
Rupert Hirst writes:
A long awaited refresh, to my previous “Anti Thump” headphone output delay circuit, designed back in 2011.
The Idea behind the circuit is to introduce a small delay, during initial power up, to electrically isolate and protect equipment connected directly to an amplifier. Often, during power up, amplifiers can produce an audible thump, through speakers or headphones. This can lead to damage of the connected equipment over time.
Thumps and clicks will occur when the supply rails voltages are too low to allow the amplifier to control its output voltage.
As the circuit has an immediate disconnect when powered off, most instances of turn off thump are also dealt with, such as output capacitor discharges.
Audio: Headphone “Anti thump” delayed output rev 1.1 - [Link]
Trevor Slaton and Dawn Xiang, students from Cornell University, designed this autonomous fire extinguisher that is capable of detecting fires through photo sensors and aiming a water nozzle along two axes to extinguish the fires. Their prototype can detect and extinguish candle fires from about 1 ft. away. Their system uses two servo motors to control the vertical and horizontal position of the water nozzle and a water pump to send out a burst of water from the nozzle. The ATmega1284p microcontroller is used to control the pump as well as the servos.
Autonomous fire extinguisher - [Link]
Inspired from one of Dave Jones EEVBlog videos on dummy load, Lee has built his own programmable constant current resistive load that allows you to draw a set current from any power supply source. His design is based on Arduino Leonardo and uses the high-power BUK954R8-60E MOSFET to control the amount of current flowing through the load path.
Constant current resistive load controlled by Arduino – [Link]
In this episode Shahriar explores the world of Delta-Sigma modulators with emphasis on a Delta-Sigma Analog to Digital Converter (ADC). The basic concepts of analog to digital conversion is presented, particularly with respect to quantization noise spectral shape and power density. Next, oversampling ADCs are presented to demonstrate the possibility of increasing SQNR (ENOB) through manipulation of quantization noise spectrum.
Due to the practical limitations of high oversampling ratios, delta-sigma modulations is explored. The principle operation behind delta-sigma ADCs is presented with detailed explanation on noise shaping, filtering and decimation. The signal and noise transfer functions for a 1st order and 2nd order delta-sigma ADC are derived. Finally, as a practical example, a 2nd order delta-sigma ADC based on a 1-bit quantizer is presented. The ADC uses two Miller integrator op-amps, one comparator and a D-Type flip-flop. The complete measurement of this delta-sigma ADC is presented. The impact of over sampling ration, op-amp linearity and input signal bandwidth is presented. The slides for this video can be downloaded from The Signal Path website.
Theory, Design and Characterization of Delta-Sigma Analog to Digital Converters - [Link]
In our portfolio can be found quality knobs from company Cliff suitable for a wide range of potentiometers and encoders.
A device with excellent specification, quality components used, …., but a one step is still missing to reach a great overall impression – it is to use a quality and aesthetic control components.
Probably you´ll agree, that knobs for potentiometers and encoders belong to a “group of critical components”, determining a resulting look of a device. Company Cliff specializes on development and production of these components already from 1977 and considerable experience are reflected in a precise construction and a wide portfolio of components produced.
● K87MAR – plastic two-color knob with a colored top part and a side line. Available in 8 standard color versions. Thanks to a big popularity and a mass production, their price is very affordable. User friendly, soft – “rubber-feel” surface. Excellent for color coding of potentiometers groups in equipment with many knobs. 6mm „D“ shaft.
● K87MBR – plastic two-color knob, very similar to series K87MAR, but only a side line is in color. Affordable price and a mild “rubber-feel” surface. 6mm splined shaft or 6 mm “D” shaft.
● K18 – universal plastic knob for electronic encoders. Available in 5 colors and 3 weight categories. In our stock can be found 2 heavier versions (35 and 50g) in a grey and black color.
● KMK – universal aluminium knob with a machined aluminium shell and a molded plastic inner. Available in a black or natural anodized surface. Push-on installation. In our stock can be found 4 versions with a 25 mm diameter – KMK25 in a black and silver (natural) color, with a 6mm splined as well as “D” shaft.
Types for splined arbors have 3 relatively robust juts (as visible on a Picture), that´s why they´re suitable only for potentiometers with deeper splines, or with a lower splin count. From our offer they´re suitable for example for Taiwan-Alpha potentiometers and they´re not suitable for potentiometers Piher series PC16.
Cliff knobs – a pleasure to touch - [Link]