Miscellaneous category

Amplifier requires no dc bias

john guy @ edn.com writes:

Intrinsically capacitive transducers and other high-impedance signal sources usually require ac coupling and a buffer amplifier to condition the signal for further processing. Buffers take many forms, but most of them compromise signal quality through the use of external resistors that provide a dc path for the input bias current. Recent improvements in op-amp technology allow ac-coupled inputs without the need for bias resistors.

Amplifier requires no dc bias – [Link]

Simple negative resistance oscillators

Bob tipped us about a simple oscillator that uses negative resistance:

Normally -according to the Ohm’s law– when the applied voltage is increasing, the current is increasing too, however some components can break this law. When the voltage increases, current decreases. This is called negative resistance.

One of the most know element that exhibits this behavior is a tunnel diode. Once very promising, today it isn’t widely used in popular designs and occupies a niche in microwave applications. It’s a bit challenging to get one, fortunately simple circuits that have negative resistance feature can be build from popular discrete elements. One of them I will present today.

Simple negative resistance oscillators – [Link]

Latching Relay Module

govindanunni@ instructables.com has build a latching relay module using 555 timer IC that is also able to interfaced to a microcontroller.

In this instructable I will show you how to use a non-latching relay as a latching bistable relay by designing a simple electronic module which is powered by an external power source. One can use this module for many other projects and it’s intentionally made portable so that one can easily carry it around. Moreover it has many other useful features which provides it many additional functionalities.

Latching Relay Module – [Link]

Digital Potentiometer using Optical Encoder – 10KOhms

The primary application of the project is to replace the mechanical potentiometer with optical encoder which is long life, accurate, smooth in operation. The simple project has been designed around LS7184 quadrature clock converter IC from LSI semiconductor, AD5220-10 Digital potentiometer from Analog Devices, and optical encoder from Burns.

Quadrature clocks derived from optical encoder, when applied to the A and B inputs of the LS7184, are converted to strings of Clock and an Up/down direction control. These outputs interfaced directly to AD5220-10 Digital Potentiometer IC.

The AD5220-10 contains a single channel, 128 positions, and digitally-controlled 10K ohms variable resistor (VR) device. This device performs the same electronic adjustment function as a potentiometer.

Digital Potentiometer using Optical Encoder – 10KOhms – [Link]

The Making of a Cooled CMOS Camera

landingfield.wordpress.com shows us their progress on how to make a cooled CMOS camera able to be used for astrophotography.

In the last post, I uncovered a bug in the Vivado implementation which accidently removes the DIFF_TERM from my input buffer. With that problem solved, I picked up the project again with a goal to achieve high speed imaging. Now I’m going to cover the design principal and its intermediate steps to achieve it.

The Making of a Cooled CMOS Camera – [Link]

LC-04 4 Channel Logic Converter 3.3V – 5.0V

If you have ever tried to connect a 3.3V device to a 5V system, you know what a challenge it can be. The LC-04 bi-directional logic level converter is a small device that safely steps down 5V signal to 3.3V and steps up 3.3V to 5V at the same time. In this instructable, mybotic explained the procedure to use the LC-04 bi-directional logic converter.

Description:

The LC-04 module offers bi-directional shifting of logic level for up to four channels. The logic level HIGH (logic 1) on each side of the board is achieved by 10K Ω pull-up resistors connected to the respective power supply. This provides a quick enough rise time of logic level to convert high frequency (400KHz I²C, SPI, UART etc.) signals without delay.

This module has the following features:

  • Dual-supply bus translation :
    • Lower-voltage (LV) supply can be 1.5 V to 7 V
    • Higher-voltage (HV) supply can be LV to 18 V
  • Four bi-directional channels
  • Small size: 0.4″ × 0.5″ × 0.08″ (13 mm × 10 mm × 2 mm)
  • Breadboard-compatible pin spacing

    The bi-directional level-shifting circuit
    The bi-directional level shifting circuit

The Pinout:

The LC-04 logic level converter has two types of pins:

  1. Voltage input pins :
    • 2 pins (GND and LV) on Low Voltage  side
    • 2 pins (GND and HV) on High Voltage  side
  2. Data channels :
    • 4 pins (LV1, LV2, LV3, and LV4) on Low Voltage  side
    • 4 pins (HV1, HV2, HV3, and HV4) on High Voltage  side

Pin HV and LV set HIGH (logic 1) logic level on High voltage side and Low voltage side respectively, with respect to the GND.

Data channel pins shift logic levels from one voltage reference to another. A low voltage signal sent into LV1, for example, will be shifted up to the higher voltage and sent out through HV1. Similarly, a high voltage signal sent into HV1 will be shifted down to the lower voltage and sent out through LV1.

LC-04 Bi-directional logic level converter pinout
LC-04 Bi-directional logic level converter pinout

Parts List:

  1.  LC-04 4 Channel Logic Level Converter
  2. Arduino Uno Board and USB Cable
  3. Breadboard
  4. Crocodile Clip (optional)
  5. Multimeter

The Wiring:

The wiring is pretty simple. You may even omit the breadboard by making end-to-end connections. Two types of connections are required:

  1. Pin connection to shift down (5V to 3.3V)
  2. Pin connection to shift up (3.3V to 5V)
Pin Connection to Shift Down:
  1. LV to 3.3V
  2. LV’s GND to multimeter’s black probe
  3. LV3 to multimeter’s red probe
  4. HV to 5V
  5. GND to UNO’s GND
  6. HV3 to Digital Pin 4
Logic level shift down using LC-04 logic level converter
Logic level shifting down using LC-04 logic level converter
Pin Connection to Shift Up:
  1. LV to 3.3V
  2. LV’s GND to UNO’s GND
  3. LV3 to Digital Pin 4
  4. HV to 5V
  5. GND to multimeter’s black probe
  6. HV3 to multimeter’s red probe
Logic level shifting up using LC-04 logic level converter
Logic level shifting up using LC-04 logic level converter

CHIP Computer Project: CPU Temperature Monitor with OLED display SSD1306

Today educ8s.tv is going to connect an OLED display to the CHIP 9$ computer in order to monitor its CPU temperature in real time.

I received the CHIP single board computer about a year ago. It is an impressive board, it costs $9 and it offers a 1GHz CPU, 256MB of RAM wifi Bluetooth and many more things. You can watch my review of the CHIP computer by clicking on the card here. As you can see the CHIP computer is a lot smaller than the Raspberry Pi 3 board and of course it costs a lot less. One year later, the software developed for the CHIP computer is mature and we can easily build some projects with it

CHIP Computer Project: CPU Temperature Monitor with OLED display SSD1306 – [Link]

DueProLogic – USB-CPLD Development System

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The DueProLogic is a complete FPGA Development System designed to easily get the user started learning and creating projects.

The DueProLogic makes programmable logic easy with an all inclusive development platform. It includes an Altera Cyclone IV FPGA, on board programming, four megabit configuration flash, and an SD connector for add on memory. You can create your HDL code, program it into the flash and interact with the hardware via a Windows PC.

DueProLogic – USB-CPLD Development System – [Link]

Meet Wembi – The World’s First, Closed Loop Conversion Kit for 3D Printer

wembi-mockup

The future of 3D printing is here and it has a name – Wembi. Boasting an advanced PID compensation system that detects issues while your 3D printer or other CNC based machine is moving, Wembi readjusts itself to eliminate printing problems and help you get the perfect prints fast!

Think of Wembi like a unique vitamin kit for your 3D printer that can boost its performance and take 3D printing to a whole new level.

A Sophisticated System That Revolutionizes DC Motor Control

Being faced with inadequate Open Loop and low precision printing in standard stepper motor technology, we decided to create a brand new, sophisticated controller that could achieve an unbeatable degree of accuracy. And we made it:

A Quantum Leap In 3D Printing Technology

By developing a revolutionary firmware and embedding it into a very simple hardware, we managed to tackle the problem of low accuracy levels and achieve unparalleled accuracy in 3D printing, unlike anything the world has ever seen so far. With important advantages over standard stepper motor technology, Wembi offers outstanding benefits.

Meet Wembi – The World’s First, Closed Loop Conversion Kit for 3D Printer – [Link]

Use a transistor as a heating element

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REC Johnson, B Lora Narayana, and Devender Sundi share their design idea on how to use a transistor as a heating element.

It is common to use transistors for driving resistive heating elements. However, you can use the heat that a power transistor dissipates to advantage in several situations, eliminating the need for a separate heating element because most transistors can safely operate at temperatures as high as 100°C. A typical example is in a biological laboratory, in which the need for maintaining the temperature of samples in microliter-sized cuvettes is a common requirement. The space/geometry constraint and the less-than-100°C upper-temperature limit are the basic factors of the idea.

Use a transistor as a heating element – [Link]