Audio Level Meter Circuit Using LM3915

This is an audio level meter hobby circuit using LM3915 sound level IC that works great on supply range between 3V to 20V . This can be used in audio amplifiers however nowadays trend is using  digital equalizer. This circuit is designed to give input voltage 1V(p-p) and a maximum input voltage of 1.4v.

Car Theft Alarm Circuit

Auto security systems are essential today to prevent our vehicle from robbery. So, nowadays people spend lots of money in  auto security systems could be a 5-20% of the cost of that vehicle. Since the auto security systems and auto alarm systems that are available in the market, may cost you huge, here is a car theft alarm that looks very simple in design and may easily implemented if you have the right ideas. This will be useful for small cars to prevent from theft. It can also be used as a auto home security system with necessary alterations.

USB Power Booster

Nowadays We always connect our external peripherals to PC by USB port. Every device requires a specific amount of power for its proper working. Since a PC SMPS can supply only a limited power to the connected devices. When too many power devices are connected to USB simultaneously, there will be occur a power shortage. The circuit shown in the figure is designed for type A USB socket. The circuit uses an  MOC3021 which is an opto-diac which triggers BT136 - TRIAC1 resulting a power availability through transformer. IC 7805 is a 5v voltage regulator which regulates the output from the bridge rectifier to give constant power supply to USB ports.

Simple FM Booster Circuit

Want to hear distant FM stations clearly? Then this will be useful to you. Here is a low cost FM booster circuit that can be used to attach to FM radio receiver to get distant FM stations clearly.  boost the signals from antenna and given to the receiver antenna. It is a low cost simple circuit  consist a common-emitter tuned RF preamplifier wired around 2SC2570 VHF transistor. Download and refer the figure for the circuit details. Pin details of  2SC2570 transistor is also given.

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Multimedia PC Speaker Circuit

Want to make a multimedia stereo pc speaker of your own?. Then get started with this simple multimedia Pc speaker circuit using TDA2822M IC. This circuit has an advantage of low-voltage power supply, low cost and wide temperature tolerance. this circuit works in single 5V power supply. So that you can give it from the usb power supply itself. The circuit can be assembled on a medium-size, general-purpose PCB and enclose in a suitable cabinet. This circuit is simple to construct and can constructed at a cost below 150RS