Telephone or extension tone ringer

The attenuation circuit is a feedback tone control system that consists of transistors and an RC network. The circuit includes a low tone control potentiometer (RP2) and a treble control potentiometer (RP3). The bass control is influenced by resistor...

FM Telephone Bug. This is a simple transmitter that, when connected to a phone line, will transmit any audio on that line (except the dial tone) to any FM radio. The FM Telephone Bug is designed to intercept and transmit...

During a telephone conversation with a distant subscriber, it is common to experience frustration due to the faintness of the voice, making it difficult to understand. To address this issue, a circuit for an inexpensive amplifier is presented. This...

When a low or high input voltage in binary form, as obtained from the converter circuit (also provided in the article) fed by a digital voltmeter, is applied, the circuit generates a low pitch for binary 0 and a...

The phone alarm device is designed to monitor and prevent unauthorized use of a telephone line. When interference signals are detected on the line due to theft attempts, the alarm activates, preventing the thief from making calls while alerting...

Children enjoy the siren sounds of police or fire brigade vehicles. This circuit is capable of generating a dual tone similar to the siren sounds of police or fire brigade cars. This circuit typically... This circuit is designed to replicate...