by Mark (Moonyoung) Lee & Kevin J. Wang:
What is seeing without feeling? The field of Virtual Reality has recently been gaining much attention, with the Oculus Rift and Google Cardboard paving the path of visualizing a world that is not physically there. But what if the virtual reality experience could be enhanced by incorporating tactile sensing? The Haptic Glove we developed accomplishes just that – without seeing the physical structure of the object, you will still be able to feel the presence of virtual objects.
The goal of the project is to create an exoskeleton on the forearm arm that provides tactile perception for the user. The volume of the virtual object will be emulated based on the intensity of a light source that is placed inside a black box. Depending on the relative brightness of the source to the phototransistors that are mounted onto the exoskeleton, a distance between the user’s hand and the light source can be determined. By varying the brightness of the LED light source, the size of the virtual object will vary. To provide the tactile perception, servos mounted on the exoskeleton provides a pulling force, preventing the user’s fingers from reaching closer to the light source. In addition to the resistive force that act against the fingers’ movement, there are also flat surfaces at the tips of the exoskeleton that will flip up to make contact with the user’s fingers, which actually provides the sense of touching a real object.
Feeling the light in a whole new way - [Link]
by dany @ elecfreaks.com:
Smart RGB LED Strip is based on the development of our BLEduino, using the Bluetooth 4.0, and the sample code written by EF men, by mobile phone APP, to control the switch of RGB LED strip, and the RGB LED color changing. The main principle is that using BLEduino mega328P chip three PWM pins respectively to control the RGB LED strip of R G B three colors. When the phone APP and BLEduino bluetooth pairing connection succeed, phone APP can control mega328P chip three PWM pins output value, then control the the color of the RGB LED strip
Smart RGB Strip with BLEduino DIY Guide - [Link]
by w2aew @ youtube.com:
This video shows a simple circuit that can be used to control the position of an typical remote control (RC) style servo with an analog voltage. The PWM (pulse width modulated) control signal format for an RC servo is reviewed, followed by the presentation of a simple circuit that can be used to control the servo with a simple adjustable DC voltage. The circuit is built with rail-to-rail op amps and a few resistors and capacitors. Note that the schematic presented doesn’t include all of the decoupling on the power supply and reference lines that you would likely want to include. A description of the circuit, as well as a more in depth discussion of each of the building blocks such as an integrator, hysteresis comparator and DC signal conditioner circuit including an attenuator, inverting amplifier and level shifter, is presented.
Circuit Fun: Control an RC Servo with an adjustable DC voltage - [Link]
Francesco Truzzi published a new build, a 3-channel (RGB) LED driver:
I built another board, which is a 3-channel (RGB) LED driver based on an inexpensive chipset called PT4115 (you can find them on eBay or Aliexpress).
The circuit is very simple and looks like Sparkfun’s PicoBuck. However, I used beefier components and a different chip. You may say it’s pretty much the same thing, but I made it to learn some more about PCB design.
Datasheet here. LED current is set through a sense resistor. The output current I is equal to 0.1/Rs. I wanted ~300mA for each channel so I chose a 0.33 ohm resistor. If you want 350mA, choose a 0.27ohm resistor.
Each channel can be controlled via PWM (you can solder male/female headers on the board), for example with an Arduino.
Building a 3-channel, high power RGB LED driver - [Link]
A battery charger is a device used to energize a rechargeable battery by driving an electric current through it. The charging protocol depends on the size and type of the battery being charged. Some battery types have high tolerance for overcharging and can be recharged by connection to a constant voltage source or a constant current source; simple chargers of this type require manual disconnection at the end of the charge cycle, or may have a timer to cut off charging current at a fixed time.
The MCP1631HV multi-chemistry reference design board is used to charge one, two, three or four NiMH batteries or one or two cell Li-Ion batteries. The board uses the MCP1631HV high speed analog PWM and PIC16F883 to generate the charge algorithm for NiMH, NiCd or Li-Ion batteries. It is used to evaluate Microchip’s MCP1631HV in a SEPIC power converter application. As provided, it is user programmable using on board pushes buttons. The board can charge NiMH, NiCd or Li-Ion batteries. It provides a constant current charge (Ni based chemistry) and constant current / constant voltage (Li-Ion) with preconditioning, cell temperature monitoring (Ni based) and battery pack fault monitoring. Also, the charger provides a status or fault indication. It automatically detects the insertion or removal of a battery pack.
The MCP1631 multi-chemistry battery charger reference design is a complete stand-alone constant current battery charger for NiMH, NiCd or Li-Ion battery packs. When charging NiMH or NiCd batteries the reference design is capable of charging one, two, three or four batteries connected in series. If Li-Ion chemistry is selected, the board is capable of charging one or two series batteries. This board utilizes Microchip’s MCP1631HV (high-speed PIC® MCU PWM TSSOP-20). The input voltage range for the demo board is 5.3V to 16V.
Multi-Chemistry Battery Charger from Microchip - [Link]
An app note from Atmel, digital sound recorder with AVR and DataFlash (PDF!):
This application note describes how to record, store and play back sound using any AVR microcontroller with A/D converter, the AT45DB161B DataFlash memory and a few extra components.
This application note shows in detail the usage of the A/D Converter for sound recording, the Serial Peripheral Interface – SPI – for accessing the external DataFlash memory and the Pulse Width Modulation – PWM – for playback. Typical applications that would require one or more of these blocks are temperature loggers, telephone answering machines, or digital voice recorders.
Digital sound recorder with AVR and DataFlash - [Link]
The LTC2645 is a family of quad 12-, 10-, and 8-bit PWM-to-voltage output DACs with an integrated high accuracy, low drift, 10ppm/°C reference in a 16-lead MSOP package. It has rail-to-rail output buffers and is guaranteed monotonic. The LTC2645 measures the period and pulse width of the PWM input signals and updates the voltage output DACs after each corresponding PWM input rising edge. The DAC outputs update and settle to 12-bit accuracy within 8μs typically and are capable of sourcing and sinking up to 5mA (3V) or 10mA (5V), eliminating voltage ripple and replacing slow analog filters and buffer amplifiers.
LTC2645 – Quad 12-/10-/8-Bit PWM to VOUT DACs - [Link]
In this Tech Lab, we look at the evaluation board for Micrel’s MIC45212, the 14 amp variant from their line of integrated medium voltage DC-to-DC power modules.
The MIC45 205, 208, and 212 modules integrate the inductor, PWM controller, power MOSFETs, and passives into the package. This integration reduces the total application size, simplifies the design and PCB layout, and improves reliability.
By integrating the passives, Micrel is able to effectively reduce the AC loop size when compared to a traditional regulator with passives routed on the PCB.
Tech Lab – Micrel MIC45212 Evaluation Board for Medium Voltage DC to DC Power Modules - [Link]
by deba168 @ instructables.com:
One year ago, I began building my own solar system to provide power for my village house.Initially I made a LM317 based charge controller and an Energy meter for monitoring the system.Finally I made PWM charge controller.In April-2014 I posted my PWM solar charge controller designs on the web,it became very popular. Lots of people all over the world have built their own. So many students have made it for their college project by taking help from me.I got several mails every day from people with questions regarding hardware and software modification for different rated solar panel and battery. A very large percentage of the emails are regarding the modification of charge controller for a 12Volt solar system.
Arduino solar charge controller and energy monitor - [Link]
by Steven Keeping @ digikey.com
Switching DC-to-DC voltage converters (“regulators”) comprise two elements: A controller and a power stage. The power stage incorporates the switching elements and converts the input voltage to the desired output. The controller supervises the switching operation to regulate the output voltage. The two are linked by a feedback loop that compares the actual output voltage with the desired output to derive the error voltage.
The controller is key to the stability and precision of the power supply, and virtually every design uses a pulse-width modulation (PWM) technique for regulation. There are two main methods of generating the PWM signal: Voltage-mode control and current-mode control. Voltage-mode control came first, but its disadvantages––such as slow response to load variations and loop gain that varied with input voltage––encouraged engineers to develop the alternative current-based method.
Today, engineers can select from a wide range of power modules using either control technique. These products incorporate technology to overcome the major deficiencies of the previous generation.
This article describes voltage- and current-mode control technique for PWM-signal generation in switching-voltage regulators and explains where each application is best suited.
Voltage- and Current-Mode Control for PWM Signal Generation in DC-to-DC Switching Regulators - [Link]