Simple Home Alarm System

This Home Alarm System is simple, secure, fast and cheap. It's only few components with maximum security with Rolling Code TX and Shock Sensor with variable sensitivity. The alarm module can be assembled in only 2 hours and it don't need manual preset.

Home Alarm System with this characteristics is the most cheap system and the total cost could be reduced using a normal external sounder (escl. AG8).GSM module will be add in the future for a remote control.

The blue led connected to the pin RA3 of micro controller is used like a memory to know if the home alarm system has been activated by an event and its reset after a reactivation. The red led connected to the power supply before the 1N5406 diode is used to check the power supply connection. Of course the other 3 micro led red near the relays are used to check the output state.

Here you can download the last version of  The Home Alarm System date 10 July 2007:

• source
•  binary (hex)

Home Alarm System in detail

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Temperature Data Logger 4 Channel

Here's a temperature data logger circuit, an 8-pin microcontroller based circuit for temperature data logging via the serial port of any computer from between 1 and 4 remote digital temperature sensors, DS1820/DS18S20 made by Dallas.

Features of the Temperature Data Logger are are follow:

• Provides realtime data via the serial port.
• Interfaces up to 4 x DS1820 sensors.
• Accuracy to 0.5 degrees centigrade
• Fahrenheit scale selected by a jumper
• No external power required
• Data stream easily logged & processed.
• Over 200m distance for each sensor

The sensors of temperature data logger may be located more than 200 yards from the PCB. Just check that the remote VDD is above 4.4Volts. It's recommends 10uF tantalum capacitors be placed across the power supply pins (not supplied) to minimise random errors and possibly get increased range.

Download :
- Circuit Schematic and Parts List
- Sensor Specs DS1820 DS18S20
- Software for Windows and DOS
- Source Code
- Terminal Emulator

More about Four Channel Temperature Data Logger

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Extech Digital Psychrometer Infrared Thermometer

Temperature can be measured using a wide variety of sensor types. Some of the more common types found in manufacturing plants are thermocouples and RTDs (resistive temperature devices) contact and infrared non-contact measurement.

 Infrared Non-Contact Measurement
All objects emit infrared energy, and the hotter an object is, the more active its molecules are, and the more infrared energy it emits. Infrared thermometers sense emitted, reflected, and transmitted energy from an object and translate this information into a temperature reading. Energy passes through the infrared thermometer’s optical system and is converted to an electrical signal, which is then converted and displayed as a temperature reading.

Infrared thermometers offer some distinct advantages over contact thermometers, since they can measure temperature without physically touching the object. Infrared temperature measurement is ideal for measuring objects that:

• Are too far or to difficult to reach
• Require non-contamination from one reading to the next
• Are moving, rotating or vibrating
• Are too time consuming for contact sensors and require quick temperature measurements
• Have high temperatures up to 3,000 F
• Can be scratched or damaged by physical contact
• Have curved, distorted or varying surface conditions
• Are too thin and soft for contact sensors
• Are too hot to touch or approach
• Are electrically active and too dangerous to touch ( by Pete Leal)

Description of Extech RH405 Digital Psychrometer IR Thermometer Kit:
Extech RH405 Digital Psychrometer IR Thermometer Kit includes: RH401 Digital Psychrometer, 33% to 75% calibration bottles, PC cable and carrying case.

See more RH401 Digital Psychrometer Infrared Thermometer Datasheet

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