LT3795 – 110V LED Controller with Spread Spectrum Frequency Modulation. by elektor.com:
It’s standard practice to use Pulse Width Modulated (PWM) signals to control electrical energy delivered to a load. Special precautions are however necessary to mitigate the effects of electromagnetic interference (EMI) generated when high-energy loads are regulated in this way. Spectral analyses of the interference generated show strong peaks at the fundamental and harmonics of the PWM frequency. For high-power switch-mode drivers used to control LED car headlights it is important to ensure the interference cannot disrupt radio or GPS reception. EMI filters and gate resistors can be used to slow down switching edges but have the effect of increasing energy losses.
Spread Spectrum LED driver - [Link]
Minimum noise, easy speed control and a high power, those are another reasons why to decide for GreenTech EC fans from EBM-Papst.
A term „EC fan“ (electronic commutation) is generally used to mark energy-saving AC fans. In fact, these are DC (brushless) fans with AC/DC module and other electronics. EC fans reach up to 90% efficiency and they consume 50% less energy than traditional AC fans.
At the same time, a typical „50Hz“ motor noise is eliminated at EC fans and practically the only noise source is aerodynamic noise depending on overall fan design.
A good example of a modern fan is for example the type G1G140-AW31-42 i.e. radial (centrifugal) fan with 140mm diameter. Efficient motor with a „Soft start“ function enables to control fan speed through a DC input (0-10V) or PWM. To check a proper function, the fan also features „Tach“ output (2 pulses / revolution) as well as locked motor protection.
Thanks to the built-in electronics, at cyclic use it´s recommended to switch-off the motor through a control signal, not by switching-off main power supply.
G1G140-AW31-42 is suitable for a continuous operation (S1) and can be mounted in any position. It´s used for example for building ventilation.
Detailed information will provide you the G1G140-AW31-42 datasheet.
Modern EC fans are able to save up to 50% of energy - [Link]
MCP19118/9 Provide Simple Analog PWM Control and Configurable MCU in Compact Circuit Solution; Industry’s First PMBus Compatible Controller With Up to 40V Operation.
Microchip Technology Inc. announced its latest Digitally Enhanced Power Analog (DEPA) controllers—the MCP19118 and MCP19119 (MCP19118/9). They provide simple yet effective analog PWM control for DC-DC synchronous buck converters up to 40V, with the configurability of a digital MCU. And they are the industry’s first devices to combine 40V operation and PMBus communication interfaces. These features enable quick power-conversion circuit development with an analog control loop that is programmable in the integrated 8-bit PIC MCU core’s firmware. This integration and flexibility is ideal for power-conversion applications, such as battery-charging, LED-driving, USB Power Delivery, point-of-load and automotive power supplies.
New Digitally Enhanced Power Analog Controllers From Microchip - [Link]
If anybody is interesed, I have posed a follow up to this original post with a simple PWM LED driver, adding an ATtiny85 mCU. The post includes schematic, board layout and code for the ATtiny85. I hav tested the circuit up to 22 volts without a current limiting resistor. The FET only needs a small heat sink. Efficiency can be further improved by replacing the LM358 with an RC/LM741. The LM741 has a much sharper rise and fall time than the LM358 when run at 2KHz, resulting in the FET spending less time as a resistor. (during the slow ramp/fall the FET acts as a resistor, generating heat)
PWM Based LED Driver - [Link]
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]