Hobby Projects - Insulation tester, LED Circuits, Meters.

Thursday, December 07, 2017

Electronics Tutorials - Ian Purdie VK2TIP

Offering free comprehensive basic electronics tutorials in amplifiers, antennas, ham radio, filters, oscillators, power supply, receivers, test equipment, transmitters, radio design and electronics design. Links to data sheets and electronics reference and text books.

Electronics Tutorials - Ian Purdie VK2TIP

Amateur Radio, Amplifiers, Antennas, Basic Electronics, Ham Radio, Oscillators, Test Equipment.

Starting out you need to cover basic electronics which encompasses the topics of ohms law, voltage, current, resistance, capacitance, inductance, reactance, impedance and Q. Further topics in these basic electronics tutorials are power supply basics as well as digital basics.

Electronics Tutorials - Ian Purdie VK2TIP

What are voltage controlled oscillators

A voltage controlled oscillator or as more commonly known, a vco, is an oscillator where the principal variable or tuning element is a varactor diode.

Monday, December 04, 2017

FreePCB - PCB editor

FreePCB is a free, open-source PCB editor, released under the GNU General Public License. It was designed to be easy to learn and easy to use, yet capable of professional-quality work.

FreePCB - PCB editor

Some of its features are:
  • 1 to 8 copper layers
  • Board size up to 60 inches by 60 inches
  • Uses English or metric units (i.e. mils or mm) for most functions.
  • Footprint libraries courtesy of Ivex Design International Inc.
  • Footprint Wizard and Footprint Editor for creating or modifying footprints
  • Imports and exports PADS-PCB netlists
  • Exports extended Gerber files (RS274X) and Excellon drill files
Example - Logic Analyzer: This is an open-source logic analyzer called MiniLA contributed by Bob Grieb of the User Forum. The image on right is the Logic Analyzer PCB.

FreePCB - PCB editor

Some Features:
  • Up to 32 channels
  • 128 Kb of memory for each channel
  • Sampling rate up to 100 MHz (timebase in 1-2-5 sequence)
  • Input levels compatible with 3.3V and 5V logic
  • Selectable pretrigger/posttrigger buffer size in 8K step

Sunday, December 03, 2017

Why Wi-Fi gaining over RJ45

The speed of data transfer on a wired connection depends on Cable, Connector and the Crimping.

Ethernet over Coax (EoC) co-axial cable. Optical and Gigabit Ethernet over Optic Fibers. Copper twisted pair and others are other means of Digital Data Transfer over Ethernet.

Why Wi-Fi gaining over RJ45

Wi-Fi and WiMax helps freeing the user from wires. Remember Wired is more secure than Wireless.

Building a RJ-45 Ethernet cable of a specific length

RJ-45 connectors and coloured caps; the latter helps to protect the ethernet connector as well as they differentiate the cables in the muddle of cables a network can produce!

Down flat... and in the right ordre to be manipulated; from left to right: white/orange, orange, white/green, blue, white/blue, green, white/brown, brown

Saturday, October 21, 2017

Simple Cheap Dark-Detecting LED Circuit

Here's a simple problem: "How do you make an LED turn on when it gets dark?"  EMS Labs.

Simple Cheap Dark-Detecting LED Circuit

When light falls on the phototransistor, it begins to conduct up to about 1.5 mA, which pulls down the voltage at the lower side of the resistor by 1.5 V, turning off the transistor, which turns off the LED......

Simple Cheap Dark-Detecting LED Circuit

Parts -On top: a CR2032 lithium coin cell (3 V). On the bottom (L-R): the LED, an LTR-4206E phototransistor, a 2N3904 transistor, and a 1 k resistor. This LED is red, blindingly bright at 60 candela, in a 10 mm package. It casts a visible beam, visible for about twenty feet in a well-lit room.