22 апреля 2009 | Автор: Admin | Рубрика: Скачать журналы бесплатно » Технические журналы | Комментариев: 0
EPE ( Everyday Practical Electronic ) June 2007
10 mb | RS.com | 77 pages | PDF Format
Bat Sonar — listen in to the sounds of bats and discover their secretive world, using our simple Bat sonar project. The circuit is a very sensitive ultrasound amplifier using a piezo input device to drive a preamplifier and frequency divider. The result is a human-audible signal that is output via a loudspeaker. Thus the ultrasonic signals of bats (and more besides) may be monitored at a level suited to the human hearing range. Included in the article are details and hints to adapt the circuit for a simple 'sonar' system and an ultrasonic remote receiver.
3V to 9V DC Converter — What a great idea! Never buy another 9V PP3/ 1604 battery again. This DC converter is an electronic switching regulator circuit that steps up a low voltage to a higher one. Two AA cells (3V) are all that are required to produce a 9V output, with up to 7 hours of continuous operation available from a pair of AA 2000mAh cells.
"Poor Man's" Q-Meter — This simple unt is constructed from a few inexpensive components but allows you to make measurements that usually require an expensive Q-Meter. In conjunction with an RF signal generator and an electronic volt meter, both inductance and "Q" can be measured quite accurately. The project will operate from AA, C or D cells. Up to 90mA current at 9V output, but can be set for 4.5V to 20V operation. The 3V Converter supports DC plugpack input and has an optional trickle charge for NiCD and NiMH batteries.
Energy Meter (Part 2) — monitor electricity consumption and costs with this PIC-powered project. LCD readout of power in Watts, energy usage in kWh, period in hours, energy cost in Pounds Sterling or Dollars. Also includes unique Brownout Protection to guard against damaging low voltage dips. Full constructional details are supplied along with free source code available from our Downloads section. Construction and calibration procedures are described this month.