Click here for a free subscription to "HDE" our site newsletter.
Email:

DIY Electronics Projects

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...

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...

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...

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.

More...

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.

More...
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...

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...

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...

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...

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...

1 of 2.. Next page >>

Now subscribe to our newsletter and don't miss a thing
 

Click here for a free subscription to "HDE" our site newsletter.