Here the notebook anti theft protector circuit to secure your important netbook / notebook from stealing. Basically, this is a mini security alarm generator. Fixed inside the notebook case, it will definitely sound a noisy alarm when a person attempts to grab the notebook. This very sensitive circuit utilizes a homemade tilt switch to turn on the alarm system through tilting of the laptop computer case.
Here the SW transmitter circuit based on IC BEL1895. This particular transmitter circuit works in shortwave HF band (6 MHz to 15 MHz), and can be applied for shortrange communication and for educational purposes. The circuit is composed of a mic amplifier circuit, a variable frequency oscillator, and modulation amplifier stages. Transistor T1 (BF195) is put to use as a simple RF oscillator. Resistors R6 and R7 determine base bias, [...]
The following schematic diagram is the circuit of solidstate automatic power-off on mains failing. A really good number of circuits which shut down the power to the load on mains failure have definitely currently shown up in EFY. This circuit is different compared to other similar circuits since it consumes no electrical power when the load is off. Further, the circuit is totally solidstate as it does not utilize any [...]
This is the door bell circuit with flashing LEDs to make the circuit more attractive. IC1 (NE555) is applied right here as being a clock generator. It is actually set up as an astable multivibrator whose frequency could be altered using the support of potensiometer VR1. The clock pulses received from IC1 are fed to pin 14 of IC2 (CD4017) that is a popular decade counter circuit module.