DIY Hobby Electronics
Arduino Pro-Mini ISP Programmer Using A UNO
The Arduino Pro-Mini is a tiny microcontroller with similar features to that of the UNO. It has a bootloader for uploading programs but unlike the UNO it doesn't have a USB interface so you need to use a USB to serial adapter to use it.
Why not use an In System Programmer (ISP) instead? You can use a cheap UNO as an ISP and you can then program the bootloader and fuses as well as the application program. Sounds like a win-win to me. More...
Voltage Multiplier - Arduino Low Voltage LED Driver
Driving an LED from a 5v microcontroller is no problem. Flashing a red, blue, green or yellow LED should be possible even with a microconroller running at 3v but what if you want to drive a white LED that doesn't strart to illuminate until it's voltage gets to about 3.1v?
Worse still what if you are designing a battery operated device and you wanted to squeeze every last second of juice from the battery by allowing the voltage to drop to the minimum the microcontroller will work at? This would be 1.8v in the case of an Arduino chip which is way short of a glowing white LED. The solution is to add a voltage multiplier to the controller output driving the LED. More...
Serial Voltage Level Converter - Arduino
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...
Servo Motor Control Systems
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...
LED Bar Graph With Transistors
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...
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...
Dremel Multitool - How To Use
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...
Sound Card Oscilloscope - Build Better Electronics Projects
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.More...
Easy Project Power Supply For Raspberry Pi & Beaglebone
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...
Raspberry Pi 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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