Electronics


Timer Circuits With 4060B
There are many applications for which a timer is very useful to turn a device on or off automatically after a preset interval - for example, switching off an irrigation system after 30 minutes of use, turning off a battery charger to prevent overcharging, etc. Timing …

Latching Relay Circuit
A latching relay is a relay which only draws power during the brief voltage pulse required to make it change state. These are very useful in situations where energy efficiency is important, but also in sitations where you need the relay to remember its state …

What is a Transistor
A Transistor is an semiconductor which is a fundamental component in almost all electronic devices. Transistors are often said to be the most significant invention of the 20th Century. Transistors have many uses including switching, voltage/current regulation, and amplification - all of which are useful …

LM741 Light Dark Sensor Circuit
A light/dark sensing circuit is extremely useful and versatile in a wide range of renewable energy projects from automatic lighting to security systems. In our article Light Dependent Resistor we explained how an LDR can be used in simple circuits to control devices according to …

PIR Sensor Circuits
In our article titled PIR Sensors we introduced passive infrared (PIR) sensors and summarised their uses. Of particular interest to us are 12 Volt DC powered PIR sensors and associated circuits since these can be powered directly from a 12 Volt battery which is in …

Repeat Timer Circuit
In our article Timer Circuits with 4060B we looked at how the 4060B binary counter can be used to make a timer. Such a timer can be used to time intervals lasting from seconds to 24+ hours, but when used as a repeat timer (i.e. …

12 Volt Programmable Timer Switch
Automatic 24 hour timer switches for 240 Volt mains electricity are very easy to find and are very cheap - prices start at just 99 pence! With such a timer (see image below) it is possible to set the times a plugged in device (typically …

LM317T Voltage Regulator Chip
The LM317T is a 3-terminal integrated circuit which can supply a load current of up to 1.5 Amps with an output voltage of between 1.2V and 37 Volts. It accepts an input voltage of between 3 and 40 volts. The LM317T is available cheaply (including from …

LM741 OpAmp Voltage Indicator
We have previously published articles* describing electric circuits which can be used to indicate when the voltage of a power source (for example, a battery bank) either reaches a certain point, or falls below a certain point. * Read Make a Simple Battery Status Monitor, TL431 …

PIR Sensors
A Passive Infra-Red (PIR) sensor is an electronic device commonly used in security lighting, and burglar alarm systems. A PIR sensor is a motion detector which detects the heat (infrared) emitted naturally by humans and animals. When a person in the field of vision of …

Example Transistor Circuit With LEDs
A Transistor is an electronic component which enables a small current to control a much larger current. This feature is very useful in many renewable energy projects and other applications. Click here to read our Introduction to Transistors. Transistors in Action - Example Transistor Circuit Pictured below …

Making Very Accurate Timers
We have previously published many articles about electronic timers - ranging from short interval timers using the common 555 IC, long interval (multi-hour) timers using a 4060B binary counter IC, and repeat timer circuits which use both. We have also looked at commercial 12V programmable …

Shunt Regulator
A Shunt Regulator is a small electronic component that clamps a power supply voltage at a fixed level. Hundreds of times per second the shunt regulator checks the voltage, and if the voltage is over thelimit then any extra voltage is dissipated as heat through …

Cheap Pyroelectric Infrared PIR Detector
In our article Hacked PIR Sensor we showed how a very cheap battery powered PIR motion sensing lamp could be used in place of a more expensive PIR motion sensors in a range of projects - primarily to switch a relay which can in turn …

Optocouplers
An optocoupler (aka photocoupler or opto-isolator) is an electronic component used to transfer a signal between different parts of a circuit which need to be electrically isolated from one another - for example, where a high voltage or high current is to be switched with …

Multiple PIR Sensor Circuits
In our article PIR Sensor Circuits we looked at how a PIR Sensor can be used in an automatic security or lighting system. We recommend you read that article before reading on. Connecting Two or More PIR Sensors There are many situations in which it is necessary …

Connect Multiple PIR Sensors Together
In our article titled PIR Sensors we introduced passive infrared (PIR) sensors and summarised their uses. Of particular interest to us are 12 Volt DC powered PIR sensors and associated circuits since these can be powered directly from a 12 Volt battery which is in …

12 Volt Battery Low Indicator LM741
The LM741 is an op-amp which has many uses in renewable energy applications. In a previousREUK.co.uk article* we looked at how this chip can be used to make a general voltage level indicator. * Click here to read the introductory LM741 Op-Amp Voltage Indicator article. In this …

Power Over Ethernet
If you have set up a collection of networked microcontrollers - for example in a home automation project and/or with a selection of sensors, one annoyance is needing to run an ethernet cable to each microcontroller AND locate the microcontroller close to a power point to …

Hacked PIR Sensor
PIR motion sensors can be quite expensive, and require additional electronic circuitry if they are to be put to use in anything other than typical domestic security systems. Options include this KC7783R PIR module designed to be used with microcontrollers or other additional electronics, or …

Convert Digital Mains Timer To Low Voltage
If you go to most supermarkets today you will see plug in mains powered digital programmable timers. These are designed to be used to automatically turn lights on and off, to turn washing machines on when you are out and so on. Prices start from …

12 Volt 7 Day Digital Timer
In our article 12 Volt Programmable Timer Switch, first published back in 2006, we discussed the difficulties in finding a 12 Volt DC powered programmable digital 7 day timer for a reasonable price despite the mains powered equivalent being available from as low as £5. At …

Make A Waterproof Temperature Probe
We include a pair of LM335Z temperature sensors with our solar water heating pump controllers. They are reliable, relatively inexpensive, and very easy to use, however they do have one disadvantage - they are not at all waterproof. One sensor has to be fitted to …

PICAXE Microcontrollers
Across our website we have plans for many electronic circuits, from solar water heating pump controllers to light detectors, and from shunt regulators to battery status monitors. As the requirements of a circuit get more complicated, the number of components and complexity of the connections …

Using Breadboard To Make Circuits
Prototyping breadboard is very useful for trying out new electronic circuits and for experimentation. Electronic components and integrated circuit (IC) chips can be plugged into the small holes and connected into temporary circuits. There is no need to solder anything, and the components can be moved …

Latching Relays
A latching relay is a special kind of relay. While a conventional relay uses power continuously when its internal switch is to be closed (relay energised), a latching relay requires only a brief voltage pulse to change state. This makes latching relays perfect for any …

KC7783R PIR Module
PIR (passive infrared) sensors are used in many applications for motion sensing. In our article PIR Sensor Circuits we looked at how a typical 12VDC PIR sensor can be used in common applications. Such PIR sensors are typically used in home security systems to be connected …

Picaxe Programming From Linux
In this article we will look at how to programme PICAXE microcontrollers from Linux. The Picaxe Programming Editor (v5) and the newer Picaxe Editor 6 are only available (at the time of writing) for Windows PCs. For anyone with a Mac or Linux machine, the …

Adjustable Step Up Voltage Regulator
There are many occasions when it would be useful to produce a useable voltage higher than the voltage provided by a battery or other power source. For example, powering a 12V LED spotlight bulb with 4 AA batteries. We have previously published articles on voltage doublers …

Convert Thermostat to 12v Timer Switch
In previous articles we have discussed the problems in finding an affordable 12 Volt Programmable Timer Switch to control low-voltage renewable energy powered lighting etc. One of the best solutions is to use a battery-powered programmable thermostat as discussed in our article Use Thermostat as …

Do It Yourself Power Meter
There are now quite a few different power meters available on the market offering the same main feature - the ability to measure directly the power used by any electrical appliance plugged into the mains. See our articles Buy UK Power Meter, Kill a Watt, …

Renewable Energy System Data Logger
With any renewable energy system it is important to track at least the status of the battery bank, and the voltage and current being used and generated. With simple domestic systems this tracking can be carried out with something as simple as a digital multimeter, …

Simple Elapsed Time Timer
We are often asked if we can supply a timer to time how long a piece of equipment is on for or a wide range of other tests. While there are many commercial elapsed time timers available (such as the hours elapsed timer pictured above), they …