Projects in the October 2000 issue of EPE Magazine

PIC Dual Channel Virtual Scope
This virtual oscilloscope interface for your PC monitors audio frequency signals and offers a number of versatile features. Easy and straightforward to construct, this dual channel design displays two traces in analogue or digital mode. Mouse-controlled, fast and versatile, uses our free QBASIC software and PIC source code.

PLEASE TAKE NOTE: Since going to press, the device specified for IC3, TC55257-DPL (and its alternative TC55257-DPI) has become obsolete. The author has proved that the NEC device UPD43256 BCZ-70LL is a satisfactory replacement and is available from Electromail (the mail order division of RS Components Ltd.) as code number 265-465. It is also considerably cheaper. Do not attempt to use any other variant of the TC55257 as it may have a different pin configuration

In November 2000 issue (P.854) we advised that since going to press, the device specified for IC3 (TC55257-DPL) and its alternative TC55257-DPI had become obsolete. The author has proved that the NEC device µPD43256BCZ-70LL is a satisfactory replacement. At the time of writing, this was available from Electromail/ RS Components in the UK ( as part no. 265-465.

Moodloop Field Strength Indicator
Check that your Moodloop (Sept. 00 issue), and find the sources of 50Hz mains fields from mains powered-equipment using this simple design. LED bargraph indication. Uses AD8532 dual op-amp and LM3914.
Wind-Up Torch
An occasional spin of the winder is all that's needed to power up our pocket-size torch. Our design uses a stepper motor as a dynamo, and Goldcap 1Farad capacitors as an energy reservoir, to illuminate a super-bright white l.e.d.. Helped by a lens, the torch offers 15 minutes of light for walking, or 90 minutes for reading. Batteries not included — or needed!
Fridge/ Freezer Alarm
A simple project, ideal for novices, this self-contained alarm unit rests in your freezer compartment or fridge and warns of increasing temperatures. Ideal to help monitor frozen goods during power cuts, or perhaps you've left the door open! Uses the TC622 single trip-point temperature sensor chip for simplicity of construction.

Also in the October 2000 issue: Interface looks at digital and analogue temperature interface for your PC; New Technology Update outlines new processor developments proposed by IBM; Circuit Surgery tests transistors the easy way.