Simple circuit lets you characterize JFETs

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by John Fattaruso @ edn.com:

When working with discrete JFETs, designers may need to accommodate a large variation in device parameters for a given transistor type. A square-law equation is usually used as an approximate model for the drain-current characteristic of the JFET: ID=β(VGS−VP)2, where ID is the drain current, VGS is the gate-to-source voltage, β is the transconductance parameter, and VP is the gate pinch-off voltage. With this approximation, the following equation yields the zero-bias drain current at a gate-to-source voltage of 0V: IDSS=βVP 2, where IDSS is the zero-bias drain current.

Simple circuit lets you characterize JFETs – [Link]

2.5A BIPOLAR STEPPER MOTOR DRIVER LV8772E

PIC1

Tiny Board has been designed around LV8772 IC from On-Semi. This driver is capable of micro-step drive and supports 4W 1-2 phase excitation. It has Low on Resistance with motor current selectable in four steps. The board is equipped with unusual condition warning LED and input Pulse Monitor LED. It is most suitable for the drive of a stepping motor for OA, amusements, hobby CNC, 3D printers, automatic machines, linear guides, motion control systems, XY gantry, Camera focus and zoom controller, Mini camera Pan Tilt Head.

2.5A BIPOLAR STEPPER MOTOR DRIVER LV8772E – [Link]

LCD Adapter Board

PIC0031

Simple LCD adapter board offers an easy way to interface a standard 16X2 LCD to your project.

Specifications

  • Very Tiny PTH PCB
  • Onboard Preset to set the Contrast
  • Easy interface with 10 PIN Box Header Connector

LCD Adapter Board – [Link]

IO expander board

C042

I/O Expander Board offers a convenient way to interface upto 16 I/O pins in your project using SPI/I2C bus.  This kit uses the famous MCP23S17 IO chip from Microhip.

Specifications

  • Supply sourced through the interfacing Box Header connector
  • The kit has 2 separate Box Header type connector for the 16 pins of I/O port and 1 Box Header for interfacing of the PCB with the host controlling circuit
  • Jumper selectable address option is also available for this kit
  • Four mounting holes 3.2 mm each
  • PCB dimensions 58 mm x 54 mm

IO expander board – [Link]

EEPROM Module

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EEPROM Add-On Board offers an easy way to interface a standard 24Cxx type I2C EEPROM to your project.

Specifications

  • 5 VDC supply sourced through the interfacing Box Header connector
  • Jumper selectable address option available
  • Four mounting holes 3.2 mm each
  • PCB dimensions 36 mm x 32 mm

EEPROM Module – [Link]

16-Bit I2C-Bus LED Dimmer

This project is devised for LED dimming using NXP Semiconductors’ PCA9532 16-Bit I2C-Bus LED dimmer. A lot of solid-state lighting applications require control over the emitted intensity of light for both functional and aesthetic requirements. Some of these applications also require a full dimming capability from fully ON to fully OFF. LED dimming potentially improves light source efficacy and lifetime.

The PCA9532 is an IC that is designed for controlling 16 LEDs over and I2C bus. It also includes the logic to act as an I2C slave device as well as the drive capability for directly driving LEDs. As well as being able to switch each of the LEDs ON and OFF independently, the PCA9532 also has two fully programmable PWM controllers that can be used to control up to 16 LEDs. Each PWM channel has a programmable period ranging from 0.6Hz to 152Hz, and a programmable duty cycle from 0-100%. This means the LEDs can be set to blink steadily and visibly, or dimmed. In this circuit, 13 LEDs are connected on pins LED0-LED12. The 1kΩ pull resistors required are fitted to the 5V supply. Once programmed, the internal oscillator allows the I2C bus to be disconnected from the PCA9532 with the LED continuing to be dimmed, something not possible with normal GPIOs. This enables electronics manufacturers to have supplementary LED dimmers in their systems, while freeing up the microcontroller and the I2C bus for more efficient operation of the system.

The I2C are targeting applications ranging from mobile phones to servers in computing, communication, and networking applications. Having a frequency range of 160Hz to once every 1.6 seconds, with a duty cycle range of completely off to 99.4% on allowing both dimming and blinking of LEDs. These new 2-, 4-, 8-, and 16-bit devices allow designers an easy way to build systems with more dimming LEDs than previously possible using just basic General Purpose I/Os (GPIO) or microcontrollers (MCUs). Manufacturers of applications such as cellphones and servers are increasingly requiring multiple blinking and dimming LEDs for eye-catching keypad lighting applications, as well as practical purposes such as status indication. The new PCA953x LED Dimmers allows more system flexibility by off-loading the LED power consumption and by eliminating the programming of the MCU.

16-Bit I2C-Bus LED Dimmer – [Link]

1clickBOM, a browser extension for quick shopping – Firefox version

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Kaspar of Monostable has released a Firefox version of his helpful purchasing tool the 1clickBOM, a browser extension to quickly add electronic components to shopping carts:

1clickBOM, a browser extension for quick shopping – Firefox version – [Link]

LM2596 DC-DC Converter Module Testing

LM2596Module

by Kerry D. Wong:

LM2596 based step-down DC-DC converter modules can be bought on eBay quite cheaply for around a dollar each. But how do they perform? Is it safe to use it to power your design? Let’s find out.

According to TI’s website, these LM2596 step-down (buck) regulators are sold for $1.8 each for a quantity of a thousand. So how a finished converter could be sold for just above a dollar each is quite a mystery to me. Anyway, the picture below is the board I received. It appears that there are a few variations to this design (slightly different inductor size or capacitor size/voltage rating, etc.) but they all are largely based on the reference design.

LM2596 DC-DC Converter Module Testing – [Link]

Freaks3D: the World’s First Portable 3D Printer

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Simplified structure. Portable so you can take it anywhere. Quality prints at breaking low price.

Take it wherever you want. The Freaks3D weighs 2.945kg and battery compatible. It is completely portable. Small enough to blend in with any table but large enough to unleash your creativity.

Less is more. Simplified extruded-aluminum beams to ensure sturdy and high-quality performance. The Freaks3D employs v-slot slider system to provide precise seamless positioning.

Quality prints on your desktop. Detailed layer resolution at fast speed. All-metal nozzle head allows PLA/TPU filaments of a rainbow of colors without easy breaks or damage. No pre-heating is needed. Simply feed the filament into the entrance path and the printer will do the rest.

Freaks3D: the World’s First Portable 3D Printer – [Link]

RELATED POSTS

“Non-breakable” interface converter combined with MCU? Wiznet is a solution.

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In the last period we can see, that producers go on the way of processors combined with interface converters grouped into a single chip. Company Wiznet also goes this way.

At the end of May 2015, Wiznet launched on the market the new W7500, combining the HW TCP/IP interface converter W5x00 with an MCU. W7500 is a solution combining ARM Cortex-M0, 128kB Flash and the HW TCP/IP. It´s suitable for applications where you use TCP, UDP, IPv4, ICMP, ARP, IGMP and PPPoE. In these devices it´s usually undesired to upgrade SW resulting in resetting a device.MCU W7500 uses HW TCP/IP thus selecting data which arrived from allowed source. W7500 processes only desired data, so “only” 50 MHz is enough. That´s approximately half the power necessary for SW TCP/IP solutions and it also doesn´t require so big Flash and RAM – as illustrated on the picture.

When comparing all data with other MCU, you can notice that with a small power you can make the same things as with the Wiznet solution. This fact is associated with not only reliability and comfort but also with approximately half the price of the chip.

Please note, that parameters mentioned in the table below are substantially lower at SW TCP/IP, while HW TCP/IP is clearly winning.

To make your development easier, Wiznet has its „wikipedia“, where datasheets, schematics, news and user guides can be found.


“Non-breakable” interface converter combined with MCU? Wiznet is a solution – [Link]