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DIY Hobby Electronics

Sound Card Oscilloscope and Multivibrators

Part of a multivib circuit

What can a sound card oscilloscope do for me? This is the question I get asked a lot and I usually say something along the lines of "No engineer can do without one". Not many people find this very helpful so I've built a simple astable multivibrator and applied the oscilloscope to it. In trying to explain what the waveforms mean I hope to answer the question better.

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Arduino Tachometer

Rotating fan illuminated by strobe

How to build a simple but useful strobe based tachometer using an Arduino Uno, an LCD/Keypad shield and a few transistors, LED's and resistors. Short pulses are generated with a simple Arduino sketch and used to drive a bank of LED's. This produces short regular pulses of light which when synchronized with the speed of a fan or motor or other rotating object, makes the moving object appear to be standing still. When this happens the light pulse rate is equal to the RPM of the object. More...

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Arduino Motion Detector

HC-SR04 ultrasonic motion detector

Building on the Arduino Distance Sensor project you can now add motion detection to the features of the device. It detects when objects appear in front of the sensor and because it's ultrasonic it will work in the daylight just as well as it does at night. This can be an advantage over passive infra-red detectors. More...

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Power Dissipated By Resistor: How To Blow Up A Circuit

A resistor burning with smoke

When you pass a current through a resistor it gets hot. The hotter it gets the more it can adversely affect the circuit that it's a part of. If it gets too hot then it can burst into flames before eventually failing completely. If this happens then it can have catastrophic consequences so it's a good idea to understand why components get hot and design circuits that don't overload the components used. I set about to destroy a resistor and demonstrate what happens when you dissipate too much power in a component. And I wanted to blow something up. More...

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Darlington Transistor Touch Switch Simple Science Project

Components of Darlington transistor touch switch on breadboard

Here is a simple two transistor darlington transistor touch switch that you can build easily on a solderless breadboard. This build follows on from the single transistor touch switch project to significantly increase the sensitivity of the touch sensor. More...

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Arduino Distance Sensor Part 2

HC-SR04 ultrasonic distance sensor

Following on from the Arduino Distance Sensor project here is an updated version of the software sketch. Two new display modes have been added and the 'Select' key on the LCD keypad is used to swich between display modes. Full explanation of the software is provided. More...

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Arduino Distance Sensor

HC-SR04 ultrasonic distance sensor

Sensing the proximity of objects can be achieved effectively using ultrasonic echo techniques. Transmitting pulses of ultrasonic sound and measuring the time it takes the echo to return does present us with some interesting challenges however.

The sound can bounce off more than one object at different distances or the pulse is scattered. Sometimes the receiver doesn't even hear the echo. Luckily these problems can be overcome and a useful instrument built using an HC-SR04 ultrasonic transceiver and a little clever software running on an Arduino. More...

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Magnifying Desk Lamp Best Tool To Buy

Magnifying lamp - My favorite electronics accessory tool I've used a magnifying desk lamp at home for more than 30 years and I've found it to be an invaluable tool for all kinds of things including building electronics projects. I want to upgrade my lamp to one with a better magnifier and a brighter, cooler LED lamp. More...

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Electronic Engineering Construction Kits For Kids And Parents

Educational electronics construction kits make excellent gifts for children. The kids won't realise that they are learning stuff because they will be too busy building diy projects and clicking together the experiments. This is one of the few kids 'toys' that encourages you to build things that really work and make it fun. More...

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Transistor Touch Switch Simple Science Project

Components of single transistor touch switch on breadboard

Here is a simple one transistor touch switch that you can build easily on a solderless breadboard. Learn how to build a circuit that turns on an LED lamp simply by placing your finger across two wires.

This project illustrates how you can use a transistor as a solid state switch. No moving parts. Exept for your finger of course. More...

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