How to switch off the appliance

[Aina]

Hi,
I am trying to control the fan via relays and pc’s parallel port.First time by running the c# code it turned on the fan but later on if i stop debugging of the program fan is not switched off.It is just swtiched off by unplugging the adapter. And second time whenever i plug the adapter it is turned on without running the program.It works by plugging the adapter just. I want to control it whenever i press the button in c# it is turned off and by pressing the other button it should be turned on. I dont know how to resolve this?? If any one knows then plz let me know.
 
Thanks in advance.
 
Regards,
 
Aina

[romel emperado]

you need stability in you program.. be specific about the logic you give to the pins controlling the relay..

[dagakshay]

hello  Aina,

Check for the following things.

does your really is still proper?

another case it migh be that your PC is now giving the pervious output what is latched by you program in the first time. so when ever you start you programe you must define all the input and the outputs. as soon you start the programe just send the a oppsite conditon on the prallel port wht you send to switch it on. now when ever you will start you code the the fan will go OFF first and as soon you press the on swith it will get ON.

i hope you got a idea what to do?

[Aina]

yes thanks i have resolved my problem.My appliances are now being controlled but can i modify the circuit of relays that you posted by attaching some temperature sensors with that circuit?? If so how to do that and which parts of circuit to modify?? Secondaly in case of appliances pc sends signal to relays when sms is recieved from gsm modem to switch the appliances but in case of relays the process is reversed. Sensors will sense any kind of temperature rise or fire and will send signals to relays that will be forwarded to pc. I dont know how to modify the circuit for sensors. Here is the circuit diagram which i followed:

http://jaspreetscodezone.blogspot.com/2008/01/interfacing-relays-using-parallel-port.html

 

If you know or have any kind of circuit diagram for this please let me know.

 

Thanks

[dagakshay]

hwllo Aina,

i didn’t get you can you be more specified what you want to change in tht ckt??? expalin those points again

[Aina]

I want to attach the smoke or fire sensor in the given circuit, so whenever there is smoke in the surrounding environment a signal is sent to pc via parallel port.

[romel emperado]

you can do that.. just input a digital signal to parallel port when fire is present..

 

 

let say the port by default is logic low then if fire is present then it will turn to logic high

[Aina]

Ok but how to attach sensors with the circuit?? the following circuit diagram i have used to switch the light on and off and is working fine.

 

http://jaspreetscodezone.blogspot.com/2008/01/interfacing-relays-using-p…

 

 

[romel emperado]

first you need to find a sensor circuit you want whatever it is..

 

understand the circuit how it works. it should have a digital output that will trigger the input of your parallel port for the program to know that the sensor senses something unusual.

 

 

example your have smoke detector circuit… when the sensor does not sense any smoke at all the output of the smoke sensor circuit is 0 or logic low and if smoke is sensed then it will trigger to logic high og 1.. thats all.. actually you need only 2 wires to do that exluding the power lines.

[Aina]

The problem is still there, i donot want to build the circuit of sensors, i just want to modify the given circuit by attaching some sort of sensor such as temperture or fire sensor. First thing is that how to attach sensors with relays as shown in the given circuit:

 

http://jaspreetscodezone.blogspot.com/2008/01/interfacing-relays-using-p…

 

 

[romel emperado]

thats not a sensor circuit.. that is only relay driver chip.. your sensor will not gonna work if you just connect directly in that chip.. go search a sensor circuit in google of your choice.

[romel emperado]

sensors are treated as INPUT devices.. and  that chip you are referring to is for  an output device….

[dagakshay]

hello Aina,

Mostly LDR is used for making smoke detector sensors.

http://electroschematics.com/2545/smoke-detector-circuit/

http://www.zimbio.com/id-Wireless/articles/xytGCwM8LuS/Smoke+Detector+circuit+Using+LDR+circuit+explanation

http://www.zimbio.com/id-Wireless/articles/xytGCwM8LuS/Smoke+Detector+circuit+Using+LDR+circuit+explanation

http://www.sensorcircuitdiagram.com/2010/11/23/smoke-detector-circuit-based-on-the-tda2002-ic/

 

use the output dirctly from emitter of transistor transistor… you need not use the rest of the ckt.

wysiwyg_imageupload:1073:

 

[Aina]

ok thanks. But how will i interface it with pc parallel port because whenever there is smoke in the surrounding environment it should pass a signal to pc indicating smoke or temperature rise.

[dagakshay]

http://www.engineersgarage.com/electronic-circuits/automatic-night-lamp

http://www.engineersgarage.com/electronic-circuit/infrared-ir-sensor

http://www.engineersgarage.com/electronic-circuits/light-sensor-photodiode

http://www.engineersgarage.com/electronic-circuits/automatic-light-dark-indicator

 

see these links that will help you out

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