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DIY Hobby Electronics

Serial Voltage Level Converter - Arduino

FTDI Serial voltage level converter

Do you have a 5v FTDI serial adapter and a 3.3v Arduino or Raspberry Pi? You know that you can't plug the adapter directly into the 3.3v microcontroller right but did you know that it's quite possible to build a simple voltage level converter to solve the problem?

I bought a 3.3v Arduino Pro Mini compatible board for a project but I made the mistake of ordering the wrong FTDI serial adapter. I got a 5v unit instead of a 3.3v one but I needed to use it quickly so I used 3 resistors to convert the levels so that I could use FTDI adapter with the 3.3v microcontroller. I thought that you might find this little converter board useful too More...

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Servo Motor Control Systems

Servo motor

Let me show you how servo motors work and what you need to do to drive them. There's a handy library that you can use with Android which makes things very easy called 'Servo'. But what if you need to drive the servo some other way? If that's the case then you will need to know something about how they work.

I will show you how to connect one up and write a very simple Arduino sketch to experiment with. I explain exactly what goes on inside a servomotor and I finish up with a set of oscilloscope traces. If you want to know more about servo motors then read on. More...

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LED Bar Graph With Transistors

LED bargraph thumbnail

How to build an LED bargraph display using transistor drivers where the number of LEDs illuminated is determined by the input voltage to the circuit. This circuit can be used to indicate temperature or water level or anything that can be converted to a voltage level.

There are a number of integrated circuits and modules available that are designed specifically for led bar graphs but if your junk box looks like mine then you probably don't have one. What if you want to build a bar graph today and don't have the right chip? I always have a small stock of transistors, diodes and resistors to hand just like most other hobbyists. So if I can build something out of these basic components then I can get the circuit working in an hour or two. Why don't you give this one a try. More...

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Sony Vaio Fan replacement

My Sony Vaio laptop was 2 years old when the cooling fan started to become noisy. Normally you would hear a faint whirring noise with a note that changed as the temperature control system altered the fan speed. This had become a noisy rattly sound that was quite objectionable.

So I ordered a replacement fan and set about the daunting task of changing it in my Vaio. As it turns out the process was not as difficult as I had expected it to be which was quite a relief. This is how I did it... More...

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Dremel Multitool - How To Use

Dremel Multitool with cutter Since I got a Dremel not too long ago I've found so many uses for it that I wonder how I ever managed without it. Most of my work is software but recently I've been asked to build quite a few prototypes for people. They may be based on an Arduino or a Raspberry Pi but every project needs a box or enclosure to keep the electronics tidy and safe. The Dremel is ideal for cutting circuit boards or making irregular holes in enclosures. Let me show you some of the things I've been using it for. More...

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Sound Card Oscilloscope - Build Better Electronics Projects

lissajous curves

You are going to need test equipment. A multimeter is essential and cheap but it will only take you so far. What you really want is a digital oscilloscope, the ultimate tool of any electronics engineer or hobbyist.

Make this the next project that you build and you will be able to use it to fault find and explore all of your future circuits. But oscilloscopes are expensive, aren't they? Yes they can be but this is a solution that everyone can afford.

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Easy Project Power Supply For Raspberry Pi & Beaglebone

DC-DC Buck converter 12 Amp

Using a Buck switching power converter makes powering all the different parts of your project a breeze. Do you need 12V for a display and 5V for your Raspberry Pi and Arduinos but you don't want multiple supplies plugged into the wall? One of these high powered converters could be the solution to your problem. More...

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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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