The Telephone project posted here is the a telephone ringer which producespleasanttunes when a call is placed to your number. The tunes produced by telephone ringer here are more melodious andsoothing compare to those of old telephone instrument and piezo buzzer in the current electronic telephone instruments. The circuit is based on the musica
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l IC UM3481/3482/3483/3484 (IC4). When the telephone senses an incoming cal signal, all the tunes stored in the ROM of the IC (IC4) are played in sequence. The bell stops ringing when handset is picked up. The complete circuit comprises of music IC, timer IC, a pair of opto-coupler followed by few other components as shown in circuit diagram (Figure 1). Diode D1 through D4 configured as bridge rectifier through which telephone line is connected. The bridge rectifier provides correct polarity to the LED inside the opto-coupler of IC1, even if the telephone line is connected in wrong polarity by accident. As we all know that in idle or on-hook condition of telephone, there is about -48 volts DC through the telephone line. The divider network is formed by combining zener diode ZD1 with resistor R2 which divides the DC voltage from telephone line. The divided voltage is again reduced by resistor R3. The reduced output voltage from resistor R3 is sufficient to light the LED inside IC1. The internal transistor of IC1 only conducts when internal LED glow and also aids transistor T1 to conduct. Hence the supply voltage is extended to the reset pin 4 of timer IC (IC3). The output of IC3 at pin 3 becomes low when the pin 2 is in high` condition. Capacitor C1 across the telephone line blocks the DC voltage of about -48 volts (because capacitor blocks DC voltage and can let only AC volts) and prevents it from reaching the telephone...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
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The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
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In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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