Design of a kind of simple and practical telephone alarm system
Posted on Feb 6, 2014
Related Circuits
New Circuits
-
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.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
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.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
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.....
.
A high impedance input is provided by Ql, a general purpose field effect transistor
A block pinout diagram of the LS7220 keyless-lock IC is shown. The keypad must provide each key...
The key to using a soundcard successfully in digital signal processing or digital radio...
Not thrilled with how a computer soundcard drove my 32 ohm Grado SR80 headphones, I decided to...
This low cost AVR development board can be used to get started with 40 PIN AVR devices or to test...
Edwin Henry Colpitts was a communications pioneer best known for his invention of the Colpitts...
This particular timing circuit can be used to time one-shot events from a few seconds to a few...
Instead of simply incrementing the time every new second, it would be great to have a display of...
This article explains how platinum resistance temperature detectors (PRTDs) can perform...
The problem is when i connect the 8051 to the encoder the data send is not received at the...
Here are two simple 12V DC motor speed controllers that can be built for just a few dollars. They...
Unfortunatately this only provides 1. 8v signals and still needs a converter to interface to the...
This software was written for this hardware. Therefore the pin allocation of the Atmel Attiny2313...
The schematic for the board can be seen below. The three main elements of the board are (1) the...
The unique circuit design, technology and reasonable structure, all-discrete components, Class A...
As shown in FIG receiver may help patients avoid missing voice in the daytime, only the receiver...
characters left: