Connected to a burglar alarm or fire alarm in the event of making phone calls playing voice messages. Controlled via DTMF actuators can operate on the spot. In recent years we have introduced several telecontrols based on the SIM900 GSM module. We released schematics and code for a gate opener (that activates when receiveing a call from a given nu
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mber), a GSM thermostat to manage the temperature of remote houses with simple text messages, a remote alarm control with DTMF and, last but not least, a remote alarm with I/O and controlled via calls or SMS. Many of these tools send text messages or place phone calls in response to changes to the electrical inputs. In some cases, especially when the receiver is a human, nothing is like a voice that clearly yields you screaming fire in progress! , or thieves in the house! etc. That`s why and also since we love things that speak (see our Voice shield for Arduino ) we decided to design a remote alarm, with text to speech capabilities and able to send DTMF commands (which allows quick and easy remote configuration). This device can be controlled by the phone keyboard and only accept calls from a defined group of numbers (8) that must be stored in the device or from any number, as long as a password is provided. Controls are there for management for output relays, inputs, as well as for some operational settings. The most attentive of you will have noticed that the schematic is missing a component, ie: the DTMF decoder where`s the mystery Well, we can do without 8870 (the decoder that always equipped our telecontrols in the past) because since few months SIM900 module can directly handle DTMF decoding. This means that all new SIM900 are able to inform the microcontroller and clearly distinguishing a DTMF two-tone from...
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.....
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