March 2011

New, Improved Theremin

This sophisticated new design of the instrument originally designed in 1919 by Leon Theremin will appeal to electronic music fans everywhere.  A Theremin is a sensitive musical instrument that is controlled by the proximity of the player’s hands. The pitch and volume are altered free-form, by manoeuvring near to the Theremin’s two special antennae.

This new design is an upgrade of our earlier design published in the May and June 2008 issues. It adds a voicing control, has a larger loudspeaker and increased power output. The power supply has also been refined. Includes volume control and line out sockets, single discrete p.c.b.  Our article contains full constructional details to enable the constructor to assemble this fascinating design with complete confidence.

Low-cost digital Audio Millivoltmeter

If you want to measure small signals at audio frequencies then this low-cost design is for you.  Based on an AD8307 log amplifier detector, PIC microcontroller and sporting a backlit LCD display, it can measure from under 5Hz to above 100kHz at 1.4V r.m.s. maximum input. 100K input impedance and ± 3% accuracy.

Full details and colour photography are included, right down to resistor colour codes, to help you construct this design successfully. Free source code downloadable from our Library.

GPS Synchronised Clock

A GPS module to convert a standard battery-operated wall clock into a precision timekeeper that never needs to be corrected. It replaces much of the clock’s electronics and generates compatible pulses that drive the clock’s stepper motor. To improve battery life, it synchronises every 44 hours and it will even automatically adjust for Daylight Saving Time. PIC 16LF88 based, with free source code downloadable from our Library.

Manual 2-Way USB Device Switch

A simple discrete way of selecting one USB peripheral or the other at the touch of a switch.  Means you can choose between e.g. USB printers or drives without having to jostle with the wiring, and you can avoid some of the bother of needing a PC to act as an always-on printer server.  LED indicator, self-powered.

Teach-In 2011 (Part 5)

The basics of op-amps. Continuing our unique educational series exploring all the basics of electronics. Includes Circuit Wizard exercises to simulate and observe electronic circuits on-screen.

Also in this issue of EPE Magazine:

• Max’s Cool Beans blog – Max proclaims that 3D is the way to go!
• Techno Talk – more insights into futuristic developments heading our way.
• Circuit Surgery – our ever popular in-house ‘surgeon’ discusses the properties of comparators.
• PIC n MIX – our monthly column dedicated to PIC programming, with the Propeller processor under the microscope.
• Practically Speaking – the feature dedicated to practical electronics workshop matters and constructional techniques. This month, how to navigate some common acronyms used in our hobby.
• Net Work – for Internet users. Our writer debugs a typically troublesome wifi network.