September 2011

This month’s highlights

Stereo DAC Sound System for DVD Players (1)

This versatile ultra-high quality design is a 24bit 96kHz-capable stereo DAC that provides sound quality equal to the best high-end CD players.  It’s the ideal accessory for discerning audio enthusiasts who enjoy listening to their CDs on DVD players but are disappointed by the myriad of hums, buzzes and distortion that their DVD player can introduce on the sound.

Our design has one S/PDIF  input and two TOSLINK optical inputs, to which you connect a DVD player, set-top box, DVR, PC or other source of PCM audio. It also has stereo phono outputs for connection to an audio system. The Stereo DAC is rack-mounted, has a toroidal mains transformer and features PCBs for the DAC, switch panel and power supply. An ATMEL  MCU is used in this project. In next month’s article, construction is described.

Digital Megohm and Leakage Current Meter

This digital display megohm and leakage current meter (megger tester) allow you to test for insulation or leakage problems at either 500V or 1000V. It measures insulation resistances up to 999M and leakage currents below 1µA.  PIC MCU based, 16 x 2 character LCD readout, switchable 500V/ 1000V test voltages. 6V dc battery operation.

WARNING HIGH VOLTAGE! This project is only suitable for assembly by advanced, skilled constructors. This is not a suitable alternative to a professionally built and certified ‘PAT’ tester.

Deluxe 3-Channel UHF Rolling Code Remote Control (Part 2)

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

In Part 2 this month, the constructional and Tx/ RX comms setup procedures are described along with Frequently Asked Questions.

Auto Dim Add-On for the 6 Digit GPS Clock

By popular request, this low-cost add-on for the Digital GPS time display (May/ June 2011) senses the ambient light level, so that a modified program running in the display’s PIC MCU can adjust the display brightness accordingly.  A small add-on board with l.d.r., and a firmware update, are all that’s needed.

Teach-In 2011 (Part 11) A broad-based introduction to electronics

In the 11th and final part of our unique educational series centred around Circuit Wizard software, after a heroic effort by its co-authors Mike and Richard Tooley we summarise the course’s contents over the last year or so and offer you a chance to test yourself with some fun quizzes.  There’s also a Teach-In Topic Index enabling readers to easily cross-refer to previous instalments.

Also in this issue of EPE Magazine:

  • Circuit Surgery –  discussing the issues surrounding op.amp attenuator circuits.
  • Practically Speaking – some hands-on workshop hints and tips.
  • Recycle It! Six fun projects to make from salvaged bits and pieces.
  • Net Work – the Internet column explains QR codes, the latest in tablets and the Chromebook
  • Ingenuity Unlimited – readers’ own circuits.
  • Max’s Cool Beans Blog – mentoring for a budding engineer.
  • Techno Talk – forget the ‘grey goo’  that is nanochemistry,  how about computers based on smart yogurt? You couldn’t make it up.

September 2011 files for download -

  • Megohm software
  • Autodim GPS

Printed Circuit Boards

We supply PCBs for all our projects going back to 2013.

New PE service – Programmed PICs

Buy programmed PICs for most of our projects.

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