Bertho posted a digitally controlled PSU design in the forum. He writes:
The design is for 0…30V and 0…3A (90W) controllable at ~1mV and ~0.1mA steps. The actual accuracy is still out for testing and I assume that noise and non-linearity will be a factor to look at when time comes. The basic design allows for 0…42V (max 45V) and (at least) 0…4A, but then all the components should be re-calculated to match such setup. Also, some components need to be voltage matched for a higher input voltage.
The design is a dual control-loop where the first stage is a switching PSU which is fed back to assure a 2.5V drop over the secondary analog control stage. The secondary stage is also responsible for the current limiter. The idea here is to reduce the power loss in the BJT (Q4) in the analog stage.
Digitally controlled bench PSU – [Link]
Watch signals propagate through basic digital circuits. Emulate any two-input logic gate using just one rLogic board and one jumper. To order rLogic+, the breadboard compatible variant, simply order normal rLogic. When the survey is sent out you will indicate which you would like.
rLogic is a basic breakout board for the Fairchild Semiconductor TinyLogic® series of Configurable Logic Gates, with an LED for watching signals and cleverly arranged header pins for simple conversion from gate to gate. Different from programmable logic, configurable logic is manually changed through rewiring using a simple shunt (AKA, a jumper), allowing you to easily and quickly morph a single pinkie sized board into any basic logic function you might need. rLogic requires no prior knowledge, but if knowledgeable of basic digital circuitry then you may jump right in with creating. If not, then a few minutes with rLogic boards will begin to teach you the basics of digital electronics.
rLogic: Affordable, Tiny, Universal Logic – [Link]
[San Francisco, CA] – Amidst the countless universities and schools raising tuition rates and cost of education, one man is stepping outside the norm and providing classes on electrical engineering completely free of charge: No ads; no memberships; just free education.
Christopher Peurifoy, a Masters of Electrical Engineering graduate from California State University: Chico and creator of the electronics website pyroelectro.com, wants to share his wealth of knowledge with anyone with an Internet connection and the desire to learn. The only obstacle in his way is the cost of funding such an undertaking. Read the rest of this entry »
To assist component and system-design engineers in selecting Texas Instruments (TI) standard-logic products, this application report is a synopsis of the information available from a typical TI data sheet. Information includes a brief description of terms, definitions, and testing procedures currently used for commercial and military specifications. Symbols, terms, and definitions generally are in accordance with those currently agreed upon by the JEDEC Solid State Technology Association for use in the USA and by the International Electrotechnical Commission (IEC) for international use.
Understanding and interpreting logic IC datasheets – [Link]
logiccircuit.org writes: [via]
LogicCircuit is free, open source educational software for designing and simulating digital logic circuits. It has an intuitive graphical user interface allowing you to create unrestricted circuit hierarchy with multi-bit buses, debug circuits behavior with oscilloscope, and navigate running circuits hierarchy.
LogicCircuit – [Link]
I’d really like to know how to “”convert”” an analog value to a digital one. In a word : I have an Arduino, a photoresistor, with a pull-down resistor. I want to know if the light is above or below a given threshold.
I know how to read the value with analogRead(photoResPin), and compare it to my threshold (in code), but I’d like to do that without software (only using digitalRead), handling that threshold in hardware.
Can you help me ?
I guess I can use a transistor, but don’t know how to “”precisely”” set the threshold (by changing the pull-down resistor value ?).
How can I convert an analog value to a digital one? – [Link]
Microchip compares mechanical and digital potentiometers to digital. This app note explains the theory behind both versions, and their advantages and disadvantages. [via]
Mechanical potentiometers have advantages in terms of having a wide variety of values available and tighter specifications such as nominal resistance, tolerance, temperature coefficient, power rating and temperature range specifications. But in many applications the overriding
factors are related to environmental and reliability issues. These characteristics are not necessarily specified by the mechanical potentiometer vendor.
Digital potentiometers go hand in hand with the drive towards digital system control. This type of potentiometer is considerably more robust that its predecessor, the mechanical potentiometer, in terms of environmental exposure issues and longevity with repeated use of the wiper. But beyond the reliability issues, the digital potentiometer offers hands-off programmability. This programmability also allows the user to repeatedly and reliably return to the same wiper position.
Comparing digital and mechanical potentiometers – [Link]
Inspired by the finding that over 60% of oscilloscope users also use a spectrum analyzer to troubleshoot embedded system designs with integrated wireless functionality, Tektronix has developed the world’s first mixed domain oscilloscope (MDO), which provides the functionality of an oscilloscope and a spectrum analyzer in a single instrument. The new MDO4000 Mixed Domain Oscilloscope series gives engineers the unique ability to capture time-correlated analogue, digital and RF signals for a complete system view. [via]
Scope / spectrum analyzer combo captures time-correlated analogue, digital and RF signals – [Link]
This project described a stereo audio amplifier using two LM386 ICs and a PIC microcontroller to control the volume of the two output speakers. The project uses a DS1868 digital potentiometer that creates a voltage divider network at the input stage of LM386 to control the fraction of signal fed to the amplifier. The potentiometer wiper position is varied digitally by the microcontroller based on the user inputs.
Digital volume control for a stereo audio amplifier – [Link]
AKTAKOM’S latest innovation features a wide screen, slim body and deep memory.
Miami Fl., June 14, 2011 – T&M Atlantic., distributer of the test and measurement equipment, today unveiled a portable digital oscilloscope by AKTAKOM that features 60 MHz bandwidth, 2 channels with a 500 MSa/s sample rate, and an 8 inch color TFT-LCD screen with 800×600 resolution. It also offers huge amounts of memory(10Mpts), and USB flash storage support. ADS-2061M is user friendly with a unique “HELP” function that allows you get a User Manual on the oscilloscope’s screen. The unit contains 2 passive probes that are switchable between 1:1 and 10:1 input ratio.
This highly portable and versatile unit is a hybrid between handheld and benchtop models. With a large screen and slim body it weighs under 4 lbs. and is 340x155x70 mm in dimension. With its optional battery, it can run for up to 4 hours.
This portable oscilloscope could be utilized for electronic circuit debugging, design and manufacturing, automobile maintenance and testing, circuit testing, education and training. It can also detect the peak and average values of a waveform, and store as much as 5000 waveform points on each channel.
Introductory Price $395.00