➀ A compact GSM-based spy device is introduced that can monitor conversations over long distances, even internationally.

➁ The device is designed to be easily concealed due to its small size and can transmit audio when a specific phone number is dialed.

➂ The project requires components such as an IndusBoard Coin, SIM800L GSM module, Li-Po battery, and microphone module, along with specific code to manage the device's functionality.

➀ An IR remote switch is a wireless device that uses infrared signals from a remote control to operate electrical appliances, commonly used in home automation.

➁ The system consists of an IR receiver module, a signal processing circuit, and a relay to control the connected load.

➂ A standard IR remote control can be used, and the circuit diagram and parts list are provided for building the IR remote switch.

➀ The article provides a step-by-step tutorial on building a function generator using the ICL8038 IC. This generator can produce square, sine, and triangular waveforms up to 100kHz.

➁ The core of the function generator consists of an oscillator that generates different waveforms, which are then shaped by wave-shaping circuits.

➂ The breadboard prototype demonstrates the functionality, with the sine waveform output captured on an oscilloscope.