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This is a simple PIC Security System Dials Your Cell Phone Circuit Diagram . Do-it-yourself phone dialer security system calls your cell phone, office etc. whenever a door or window is opened, or panic button is pressed. Great Home Alarm. PIC Security System Dials Your Cell Phone Circuit Diagram The circuit consists of a small PIC microcontroller, assembly program, and a few other parts to detect a switch closure from an open door, window, or manual push button and then dial the cell phone number, and transmit a steady tone to indicate the source of the call. The circuit uses the pulse dialing system to interrupt the line connection a number of times to indicate each digit. Pulse dialing (the oldest form of dialing) works by actually disconnecting or "hanging up" the phone line a number of times to indicate each digit. For example, the digit "5" would be dialed by disconnecting and reconnecting the line 5 times in short intervals of about 100mS. There is about a 1 s...

Battery-backup converter with one NiCd cell Notebook computers and added carriageable accessories generally use a advancement array to absorb anamnesis accommodation during advancement of the capital battery. Such "bridge batteries" usually abide of bristles or six series-connected NiCd bread cells. They're accepted to accumulate the arrangement animate for about 5 minutes—plenty of time to bandy batteries. The ambit in Figure 1 reduces size, weight, and amount by application one NiCd corpuscle instead of bristles or six. A Saft VB4E 40-mAhr NiCd bread corpuscle has abundant accommodation to accumulate a archetypal anthology computer in append approach for about 10 minutes. All apparatus (excluding the bread cell) absorb beneath than 1/2 in.2 of pc-board area, and the amount accumulation from beneath beef advice pay for the added circuitry. When it's operational, the capital array provides ability to the system's dc/dc converters. The LT1304 addition advocate con...

High efficiency white LEDs have advanced to the point where they can replace glow bulbs and other light sources not only as indicators, but also for illumination. While many of the claims made about the LEDs' efficiency, light quality, lifetime and economy are mostly exaggeration, the truth is that for very low light levels they are now competitive. They have equal or slightly higher efficiency than a flashlight bulb, a longer lifetime, and are very much tougher. On the other hand, they are still far more expensive than a bulb, for a given light output. It follows that LEDs are almost ideal for very tiny, low power flashlights, in the less-than-one-watt category. But such a low power flashlight makes sense only if the whole flashlight is small and lightweight, and has a reasonable battery lifetime. But white LEDs require about 3.3 volts each, and typically some extra voltage is needed to provide room for current regulation! That's why most commercial LED flashlights use at leas...

High efficiency white LEDs have advanced to the point where they can replace glow bulbs and other light sources not only as indicators, but also for illumination. While many of the claims made about the LEDs' efficiency, light quality, lifetime and economy are mostly exaggeration, the truth is that for very low light levels they are now competitive. They have equal or slightly higher efficiency than a flashlight bulb, a longer lifetime, and are very much tougher. On the other hand, they are still far more expensive than a bulb, for a given light output. Cell LED Flashlight Circuit Diagram It follows that LEDs are almost ideal for very tiny, low power flashlights, in the less-than-one-watt category. But such a low power flashlight makes sense only if the whole flashlight is small and lightweight, and has a reasonable battery lifetime. But white LEDs require about 3.3 volts each, and typically some extra voltage is needed to provide room for current regulation! That's why most co...