Showing posts with label monitor. Show all posts
Showing posts with label monitor. Show all posts

Sunday, May 5, 2013

Temperature Monitor Circuit Diagram

A simple op-amp circuit that will trigger a relay when a preset temperature is reached. Please note that there is no hysteresis in this circuit, so that if the temperature changes rapidly, then the relay may switch rapidly.

Temperature Monitor Circuit Diagram

Temperature-Monitor-Circuit-Diagram
Circuit Notes:
This circuit uses an ordinary NTC thermistor with a resistance of 47k at room temperature. A suitable part from Maplin Electronics is FX42V. The circuit is set in balance by adjusting the the 47k potentiometer. Any change in temperature will alter the balance of the circuit, the output of the op-amp will change and energize the relay. Swapping the position of the thermistor and 47k resistor makes a cold or frost alarm.

Calibration:
At room temperature (25 degrees Celsius) a 47k NTC thermistor resistance is approximately 47k. The non-inverting op-amp input will then be roughly half the supply voltage, adjusting the 47k pot should allow the relay to close or remain open. To calibrate the device, the thermistor ideally needs to be at the required operating temperature. If this is for example, a hot water tank, then the resistance will decrease, one way to do this is use a multimeter on the resistance scale, read the thermistors resistance and then set the preset so that the circuit triggers at this temperature.

Please note that if the temperature then falls, the relay will de-energize. If the environment temperatures changes rapidly, then the relay may chatter, as there is no hysteresis in this circuit.

Hysteresis, allows a small amount of "backlash" to be tolerated. With a circuit employing hysteresis, there will be no relay chatter and the circuit will trigger at a defined temperature and require a different temperature to return to the normal state. Hysteresis can be applied to the circuit using feedback, try a 1Meg resistor between op-amp output, pin 6 and the non-inverting input pin 2 to give the circuit hysteresis.

Without offset null adjustment, the output of the 741 IC will be around 2 Volts (quiescent) swinging to nearly full supply when triggered. The 4.7k and 1k resistor form a potential divder so that under quiescent conditions the transistor will be off. Quiescent or steady state means no signal, or in this case (when the temperature does not cause the output to swing to full voltage) link
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Saturday, April 13, 2013

Non Contact Power Monitor circuit

Here is a simple non-contact AC power screen for house appliances and laboratory equipment that should stay constantly switched-on. A fuse failure or power breakdown within the tools going overlooked may just result in irreparable loss. The monitor sounds an alarm on detecting energy failure to the equipment. The circuit is built round CMOS IC CD4011 utilising just a few components. NAND gates N1 and N2 of the IC are wired as an oscillator that drives a piezobuzzer instantly. Resistors R2 and R3 and capacitor C2 are the oscillator elements. The amplifier comprising transistors T1 and T2 disables the oscillator when primarys power is available. In the standby mode, the base of T1 picks up 50Hz primarys hum all the manner through the positive half cycles of AC and T1 conducts.

Circuit diagram:
   
Non-Contact Power Monitor circuit diagram
  
This offers base current to T2 and it additionally habitss, pulling the collector to ground potential. As the collectors of T1 and T2 are connected to pin 2 of NAND gate N1 of the oscillator, the oscillator will get disabled when the transistors behavior. Capacitor C1 forestalls upward throughst of the collector voltage of T2 once more right through the terrible half cycles. When the facility fails, the electrical field across the equipment’s wiring ceases and T1 and T2 turn off. Capacitor C1 begins charging via R1 and preset VR and when it will get sufficiently charged, the oscillator is enabled and the piezobuzzer produces a shrill tone. Resistor R1 give safety tos T2 from short circuit if VR is altered to zero resistance.

The circuit can be easily assembled on a perforated/breadboard. Use a small plastic case to enclose the circuit and a telescopic antenna as aerial. A 9V battery can be used to power the circuit. Since the circuit attracts only some microamperes current within the standby mode, the battery will closing a couple of months. After assembling the circuit, take the aerial close to the primarys cable and modify VR except the alarm stops to indicate the standby mode. The circuit will additionally be placed on the gear to be displayed as regards to the principles cable.


http://www.ecircuitslab.com/2011/06/non-contact-power-monitor-circuit.html
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Monday, April 1, 2013

Treatment LCD monitor

Treatment LCD Monitor. At this time computer use familiar and already widely used either for work or entertainment. And of course when talking about computers it will not be far away with a device called a monitor. And today use CRT monitors have started to decrease with the LCD Monitor that despite having a price that is quite expensive but have many advantages than conventional CRT monitors.


Here are a few advantages of LCD monitor is a stylish design, flat screen and a brighter color than convex or crt monitor screen, while also LCD Monitors have many advantages among which have a high resolution so that it can help many people especially those working Visual design field.

There are some special treatment for LCD monitors in this case is for the treatment of LCD monitors, the following are some steps steps:

Use the LCD as needed, Do not use if you do not need so-necessary and do not use it 24 hours nonstop jedanya have no time for any electronic item there during his lifetime (Lifetime). Turn off your LCD monitor when your computer dies, in order to save electricity and also keeps your LCD monitor remain durable.
Use the type that has a grounding electrical power, because it can minimize the damage in the event of lightning strikes. This option is optional.
Perform regular cleaning, at least 2 weeks 1 times, for LCD monitors are always in a state clear of dust and other debris. Remember! to clean it must use a very soft cloth that has spread with a special liquid cleaners LCD monitor. If necessary you can buy special equipment to clean the LCD monitor.
Do not engage in cleanup activities in the state of electricity is still flowing, unplug all cables available on the LCD to avoid things that are not desired. The existence of water coming into the series of LCD monitors will be able to cause fatal damage.
Keep the LCD of the things that contain water such as rain water, drinking water etc.. Because all electronic goods electrical short circuit will occur if water enters into the electronic components.
Keep the LCD of goods containing such magnetic sound system, Persani, HP etc. signals. Because it will be fatal is going to happen Noise or damage which may destroy the layout on the monitor screen.
LCD Save a strategic place and safe from the reach of small children, so that you can not avoid tersenggol LCD or a small toy.
Unplug all cables associated with the computer (including LCD) in the event of rain accompanied by lightning, because lightning can be grabbed via the antenna propagate through the cable TV and electricity.
To protect the screen / LCD screen can use the Screen Protector function prevents dust entry into the LCD and also take care of all sorts of scrapes. Remember to choose the screen protector is not a trace when reopened.
If there is damage to your LCD monitors, LCD submit to the experts. Do not disassemble itself without accompanied by experts in the field of electronics. Module Components including LCD monitors that can be easily damaged. LCD Monitor Service you to the service center to ensure the improvement is good and right.
Good article on the LCD monitor is beneficial treatment.
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