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A simple circuit, High-Pass filter, variable between frequencies 20HZ until 200HZ, useful in a lot of cases elaboration of sound signals. The regulation is achieved with the double potesometer 47KΩ and the frequency response in his two extreme places, appears in the schematic....
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Most, if not all, recent cars have an impressive amount of electronics, whether it be ABS brake systems, engine control with injection calculators, airbag activation, or other various functions, called comfort functions. Among them is one which we tend to forget because it has become so common today. It turns on the windshield wipers automatically for a few seconds after the windshield cleaner. This practice is almost indispensable because it avoids any dripping of excess rinse product right in the middle of a just-cleaned windshield....
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These are two - easy to build - relay-based alarms. You can use them to protect your motorcycle - but they have many more applications. If you use relays with 6-volt coils - they'll protect your "Classic Bike". Both alarms are very small. The completed boards occupy about half a cubic-inch - 8 cc. The standby current is zero - so they won't drain your battery....
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Here is the circuit diagram of Two Flashing LED's for different applications (such as model construction), and recreational. Having adjustable flashing speed with two potentiometers. It is the collection of a few active and passive components. This circuit is very easy to built ( a good idea for beginners ) and can be build on a general purpose pcb or on a veroboard. The complete picture and schematic of this project is shown below...
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Here is a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio....
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A very simple device allowing a quick check of common Infra-red Remote-Controls can be useful to the electronics amateur, frequently asked to repair or test these ubiquitous devices. A reliable circuit was designed with a handful of components: the LED will flash when any of the Remote-Control push buttons will be pressed. The side of the Remote-Control bearing the IR emitting diode(s) must be directed towards the Photo Transistor (Q1) of the checker circuit: maximum distance should not exceed about 20 - 25cm....
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