Telephone Ringtone Generator

This is really a very simple home telephone ring tone generator circuit which is built with applying only several electronic components / parts. It generates simulated telephone ring tone and requires only DC supply with 4.5V DC to 12V DC voltage. One may possibly use this circuit in ordinary intercom or phone-type intercom. The sound… Read More »

Automatic Switching-on Emergency Light

Automatic Switching-on Emergency Light The schematic diagram shown right here is the automatic switching-on emergency light circuit which is controlled using IC. The most important capabilities of this circuit are: automatic switching-on of the light on main power failure and battery charger with overcharge protection. When mains electrical power is absent, relay RL2 is in… Read More »

Pyroelectric Fire Alarm System

This is definitely an ultra-sensitive fire sensor that exploits the direct piezoelectric property of an ordinary piezo component to recognize the fire. The lead zirconate titanate crystals within the piezo component have the property to deform and produce an electrical potential when heated, thus converting the piezo component into a heat sensor. The circuit mentioned… Read More »

Report: DC/AC Pure Sine Wave Inverter

Here the project report of DC/AC pure sine wave inverter. This report focuses on DC to AC electrical power inverters, which aim to efficiently transform a DC power source to a high voltage AC supply, just like electrical power that would be presented at an electrical wall outlet. Inverters are utilised for a lot of… Read More »

4 Stage FM Transmitter

This is the FM transmitter circuit which apply 4 radio frequency stages, that are a VHF oscillator designed around transistor BF494 (T1), a preamplifier designed around transistor BF200 (T2), a driver designed around transistor 2N2219 (T3) and also a power amplifier designed around transistor 2N3866 (T4). A condenser microphone is wired at the input of… Read More »