Projects in the November 2000 issue of EPE Magazine

PIC Pulsometer
Our PIC-powered project accurately measures and displays pulse timings, frequency and capacitance. Frequency range 0.00015Hz - 40MHz; duration 25ns - 1.9 hours; capacitance 1pF - 999µF. Single line LCD display, stripboard assembly. Free source code available for download from the EPE FTP site.

In November 2001 (P. 799) issue we advised that resistors R2 and R3 should have the values shown in the circuit diagram (Fig. 2), not those shown in the parts list.

Opto Alarm
This novel alarm unit is a portable unit which responds to fast changes in light levels (e.g. an intruder's torch/ flashlight), but it cleverly ignores natural dusk-dawn ambient transitions. Exit and entry delays, test function. Battery powered, self contained, siren alarm output.
Handclap Switch
Electronics making life easier for you! This sound-activated awitch drives a mains-relay with just a handclap. Electret microphone provides simple toggle on-off control or auto-switch-off function.
Part of our series of starter projects that can be build for a “tenner” ($7), this sample/ hold circuit is an add-on for your digital or analogue multimeter. It samples and holds a changing voltage giving you time to read the display. Stripboard assembly. Requires DG419D single MOSFET transmission gate.
New series - the Schmitt Trigger
A new short series, this month we present a detailed analysis of the Schmitt trigger based on bipolar transistors. Everything you ever wanted to know about Schmitt triggers will be found in this detailed article!

Also in this issue: Circuit Surgery discusses the theory behind ELCBs (RCDs - GFCIs); Ingenuity Unlimited offers more readers' circuits. New Technology Update - how a new combined dual chipset improves digital imaging.