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Keypad Alarm — This sophisticated yet easy to build stand-alone project can be used in home, office or car security systems or could form part of a larger alarm ystem. A standard 4x3 matrix keypad can be mounted remotely via a cable or sited directly on the housing. PIC 16F84 based. Various input and output options are described. Free source code downloadable from our Downloads area. Please note: software updated May 2006.
- Choose 1-12 digit codes
- Separate Master and User codes
- Service Code to alter parameters
- Duress code to start alarm
- Instant and delay inputs
- Exit delays
- and more!
Status Monitor — Is your boiler or freezer still on? You can remotely monitor them with our indoor wireless status monitor. It comprises a transmitter that is placed close to the appliance and is wired to a small sensor attached to it. The sensor is a phototransistor that is intended to monitor a lamp or l.e.d. on the system. The receiver is placed where it can easily be seen, and it mimics the status of the lamp/ l.e.d. being monitored.
Based on HT12E/ HT12F controller chipset. Commercial 433MHz RF modules are used. Full constructional and interwiring diagrams are provided in full colour, enabling you to build the unit in complete confidence.
In April 2006 issue P8 we said, the Receiver section should have a 5V 78L05ACZ regulator in place of the 8.2V 78L82ACZ. To then increase the brightness of the LEDs, reduce R4 to 270R and R3 to 220R. The transmitter regulator is correct.
Active 3 Way Crossover — Our 3-way stereo active crossover is intended for audio enthusiasts wanting the very best from their 3 way loudspeaker system. It avoids the disadvantage of passive crossover networks and allows the power levels to the speaker to be optimised. Comprises a stereo pair of low, high and bandpass filters for woofers, tweeters and midrange speaker sets. 1U rack case, toroidal transformer design, individually variable trimpots. Made from low cost standard components. 
Jazzy Heart Necklace — for Valentine's Day or for fun loving partygoers, our Jazzy Heart jewellery uses multi coloured l.e.d.s and a simple 4000 CMOS chip to create a flashy display. PCB is 60mm high and can be re-shaped or adapted for other occasions, e.g. Christmas or St. Patrick's Day, to produce a bright eye-catching novelty.
Download author's video clip (Jazzy Heart.mov) : click here
Teach-In 2006 Part 4: EPE is famous for its educational electronics series, and Teach-In 2006 starting in the November 2005 issue is a great new 10-part tutorial written specially for beginners in electronics. No prior knowledge is assumed. Special online test available – and the chance to win a valuable prize. Sponsored by Rapid Electronics.
February 2006 Teach-In 2006 (Part 4): Semiconductors, introducing diodes, LEDs, thyristors and rectifiers. Practical and easy to follow demonstrations are also given.
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