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The purpose of this circuit is to animate shop-windows by means of a capacitive sensor placed behind a post-card-like banner.... [read more]

This is a single zone alarm - with independently adjustable Exit, Entry and Siren Cut-Off timers. When the alarm is activated its Siren will sound once - for up to 20-minutes. Then it will switch off and remain off. If you wish - you can use a mains power supply. But the extremely low standby current makes battery power a realistic option.... [read more]

This circuit turns-off an amplifier or any other device when a low level audio signal fed to its input is absent for 15 minutes at least. Pushing P1 the device is switched-on feeding any appliance connected to SK1. Input audio signal is boosted and squared by IC2A & IC2B and monitored by LED D4. When D4 illuminates, albeit for a very short peak, IC3 is reset and restarts its counting.... [read more]

This circuit is design, in order to is heard the voice above the music. Useful for DJ, for small radio stations, for statements above the music, in shops etc. Also we can him use in applications that we want to handle some unit with our voice. As it has the circuit has become forecast for stereo music and monophonic microphone, but can be modified and be adapted in the needs or in the use that we want, him we use.... [read more]

Here is the simple virtual ground circuit based on discrete components. This simple design comes from miniaturization guru Sijosae. Is to make a buffer from generic discrete components. The transistors can be most any complementary pair of small-signal transistors. Suitable alternatives are the PN2222A and PN2907A. The diodes are generic small-signal types. An acceptable alternative is the 1N914. This circuit has better performance than a simple resistive divider virtual ground, and the parts cost is lower than for any other circuit mentioned here. It is, however, the least accurate of the buffered virtual ground circuits.... [read more]

This circuit was developed to charge the Lithium-Polymer cells used in a model aircraft. Lithium-Polymer cells are incredibly lightweight compared to Ni-cad battery packs of the same voltage and amp-hour rating. Their only drawback is that they require a rigid charge and discharge regime to achieve maximum life.... [read more]