Automatic telephone responder circuit is shown in Fig. FIG IC2 10 seconds voice recording circuit SR9G10A, press the power switch S2, can be built by IC2 electret microphone in
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put if you want to tell a friend. Before going out to press the switch Sl, static triode VTl, composite pipe collector voltage VCE VT2 composed of about 0.65V, diode VD2, transistor VT3 nonconductive.When a call hit, the phone ringing, ringing signal negative half-cycle so that ICl 4N35 optocoupler conduction, IC2 of PLAYE grounded (equivalent to a falling edge of the negative pulse trigger) while playback, the audio signal all the way to unilateral after the composite tube amplification, the transistor VT2 of VCE increases, VD2, VT3 turn, relay Jl pull, the resistance Rl analog outside line off-hook (telephone DC resistance of about 300 ); another unilateral way audio signals added to both ends of the telephone line, so your friends hear your voice input in advance. When the sound after sowing, the circuit back to the static relay J1 release, the entire state of the circuit corresponds to hang up.
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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