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DIY Hobby Electronics

Raspberry Pi UPS

Battery + Diode for very simple UPS

Small and inexpensive microcomputers like the Raspberry Pi and Beaglebone are increasingly finding applications requiring unattended operation. You can now deploy an affordable solution to all kinds of monitoring and control applications using computers that fit in your pocket. But there is a catch. Computers need to be shutdown in an orderly fashion before power is removed to avoid corruption of the file system which can potentially render it useless. So what happens if there is a power outage or someone removes the power by mistake?

There are two ways to minimise the possibility that your raspberry Pi becomes as useful as a house brick. One way is to ensure that power is never denied to the computer should the mains power fail. Or you can detect a power fail condition and have the computer shut itself down until power returns. This series of articles looks at a variety of simple solutions to this problem. More...

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Long Time Delays With A 555 Chip

555 circuit I've been looking for a simple, low power, method to generate long time delays so that I can power up a datalogger at regular intervals to take measurements then shut it off again to save battery. I found that the humble 555 timer integrated circuit is more than up for this challenge. More...

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A Power Off Delay For Computer Shutdown

Long delay circuit Cheap microcomputer boards like the Raspberry Pi and the Beaglebone are finding applications in many places. They bring breathtaking computer power to seemingly simplistic tasks opening up a world of possibilities. But they are microcomputers and you can't simply switch them off without performing an orderly shutdown. If you do you risk corrupting the file system and rendering the device unusable. More...

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How To Make A Free Sound Card PC Oscilloscope

PC based oscilloscope signal traces A good oscilloscope can cost you a lot of money but you can build this PC based oscilloscope for less than a decent cup of coffee. Yes it has limitations but if you have no way of observing the signals in your electronics projects and you can't afford to buy a full featured oscilloscope then this little project could be the answer to your prayers. Not only does it give you a dual channel oscilloscope but it will also do a Fast Fourier Transform analysis of your signals too. More...

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Sound Card Oscilloscope Software

Sound card oscilloscope display I was so impressed by the potential of the Sound Card PC Oscilloscope probe described in an earlier article that I decided to look for alternative software packages that could be used with it. I found one that appears to deliver better results which I am posting here. More...

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Raspberry Pi Beginner Projects: Setting Up

Raspberry Pi board legend

Get your Raspberry Pi setup and ready to develop projects. If you haven't seen what this little baby can do yet then you are in for a treat. Find out how to download and flash an operating system onto an SD card. Learn how to connect it up then communicate with it remotely as if you where there. Connect it into your local network so that you can share files. More...

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Getting Started With Electronics Review

Book cover If you are a complete beginner to electronics then this is the book for you. It takes you right from the time that you had your first curious thought about how things work right through to building your own circuits on breadboards. There's no time wasted getting there either. It's a no nonsense, straightforward guide to getting started with your hobby without taxing you to understand loads of theory. More...

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How To Measure Output Impedance The Easy Way

Z is for Impedance

Output impedance can seem a bit like black magic until you realize that it's really quite simple. Here is an easy yet effective way of measuring the output impedance of almost any circuit. I've avoided turning this into a full-on mathematical treatment of impedance that would bore you to tears. Instead I give you an easy to understand practical feel to the problem instead.

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Simple Transistor As An Amplifier

Simple amplifier circuit

Build a simple one transistor amplifier circuit that you can use in many projects where you need to amplify small signals. A circuit like this could form the basis of a high quality audio preamplifier and it only uses five components. There is a catch though. Find out what it is in this project article.

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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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