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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 simple electronics which encompasses the topics of ohms law, voltage, current, resistance, capacitance, inductance, reactance, impedance and Q. Further topics in these 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.

Electrician Tool – Continuity Tester

I had gone to buy some long wires at a electrician shop, when a terminal box had to be tested, he used a continuity tester.

When i used to buy electrical parts in the past, they used a tester box, made of wood. This had a bulb and a tubelight starter and two long wires (230v AC). The Continuity tester would light up a 40w lamp. Now he had a LED based one, so i got one for myself.

Electrician Tool - Continuity Tester

All it had, was two small cells in a plastic box with a LED, i was just flashing the LED as it looked nice thru the transparent box, it failed. The LED had burnt, the battery used. This product was not for monkeying around.

Now i performed a tiny design upgrade, I used a extra-bright 3mm Red LED with a 47 ohm resistor. Now it is robust, at least for continuity. The battery life can be good only if you make quick checks.

Improvements –

More protection may be needed to avoid damage to LED when this tester is applied across a battery by mistake. LED can flash to save battery power, one SMD – LM339 can be used for flashing and a more efficient short-leakage detector. A small oscillator with a neon may be more efficient and bright. This can also double up as a hidden Live wire or Mains AC detector.

Continuity Tester Circuit

A single chip metal detector with a range of a few inches. This is useful for detecting nails or screws in walls and floors, or for locating buried mains cable.

Continuity Tester

This article describes a simple continuity tester, based on an ATtiny85 and a piezo buzzer, designed for checking circuit wiring, or tracing out the tracks on a PCB: