August 2011

SD Card Music & Speech Recorder/Player

This digital recorder stores monaural .wav files  on low-cost MMC/ SD/ SDHC cards. You can use it as a jukebox, a sound effects player or an expandable dictation machine,  in free-standing mode or with any Windows, Mac or Linux computer. It also features a keypad and a ‘learning’ IR remote control  function, and informative 2-line LCD display.  Uses FAT/ FAT32 filesystem to transfer files to a PC. Depending on the filesize you can store many hours of audio on a memory card.

This advanced project is fully explained in our highly detailed article, showing all interwiring diagrams and layout in full detail, so you can build the project with confidence.  PIC micro based. Free source code available from our Library.

Digital Audio Millivoltmeter Input Attenuator

If you’d like to use our Digital Audio Millivoltmeter (EPE  March 2011) project to measure AC voltages up to 140V r.m.s. then this add-on project is the answer. It’s a simple switched input divider using low-noise metal film resistors that lets you add 40dB, 20dB or 0dB of attenuation ahead of the meter, at the touch of a knob.  Simple all-PCB design.

Deluxe 3-Channel UHF Rolling Code Remote Control (Part 1)

This fantastic high-security 3-button UHF system offers keyless entry into homes or commercial property, or can equally be used for controlling eg garage doors or external lighting. It’s an all-new design offering advanced security and maximum functionality. Three separate mains relay outputs on the receiver can be utilised for driving loads, and up to 16 transmitters can be used with one receiver for maximum flexibility. PIC 16F88-based, free source code available from the Library at epemag.com

Key transmitter features include:

• 433MHz UHF data transmitter
• Three function buttons
• Coding randomisation
• Rolling code UHF transmission
• Extremely low micropower quiescent current

Receiver:

• Use with up to 16 separate transmitters
• Three independent 230V relay outputs
• Door strike driver output
• Momentary or toggle operations
• Many more features too numerous to mention!

Teach-In 2011 (Part 10) –
A broad-based introduction to electronics

In part 10 of our unique educational series we look at the practical aspects of electronic circuit construction and testing. The multimeter and oscilloscope are introduced and we explore basic techniques that can be used to design, construct and test printed circuit boards within Circuit Wizard.

Also in this issue of EPE Magazine:

• PIC n MIX – our column for PICmicro enthusiasts introduces a major new development from Microchip, the MPLAB-X IDE. Screenshots and walk-throughs are included.
• Circuit Surgery – our in-house ‘surgeon’  examines the topic of noise simulation using LTSpice.
• Interface on the classic DAC 0800 and ADC0800 converters, still a valuable part of the electronics toolkit.
• Net Work – the Internet column sheds light on QR codes with pointers to interesting websites.
• Techno Talk – looking into the future, in the shape of memristors.
• Max’s Cool Beans blog – from a tornado-shattered community