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
AlarmThis 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.
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.
Sample-and-HoldPart 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 TriggerA 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.