marcusaurelius
- Dec 13, 2016
- 8
- Joined
- Dec 13, 2016
- Messages
- 8
To introduce myself, I am a sophomore electrical engineering student.And I am required to design an air conditioner for my term project. Normally this thing is done in groups of two, but my partner is (which i didn't know when i picked him) kind of (absolutely in fact) useless. So now i am stuck with something that i know little about.
The project is schematically as follows :
Sensing Unit -> CONTROL UNIT -> Heating and Cooling Functions.
Temperature Adjustment Unit ---> CONTROL UNIT ->
Basically sensing unit (operating with an LM 35 chip) detects the outer temperature and yields a dc voltage directly proportional to temperature in celsius (eg. for 27 degrees of ambient temperature, it yields 270mV)
Temperture Adjustment unit is where input occurs. User sets (using buttons or whatever) a square wave with a specific duty cycle so that %0 duty cycle wil be evaluated as -50 celsius and %100 duty cycle (simply a DC signal) will be interpreted as +50 celsius. This data will be our desired temperature.
These two pieces of information are then gathered at the Control Unit. This thing compares the two , and if it is hotter than desired, it will run a DC fan (how effective, right? ) and if it is colder than expected it will give current to a stone resistor. The system will stop running when the diffeence between desired and ambient temperatures are less than or equal to 2 degres.
Even though it all may seem a little simple i am very confused. And unfortunately, the material we can use are limited to : (directly copied from the project file) You are allowed to use +/-25 V output of DC power supply and you may use any types of resistors, capacitors, inductors, diodes, LEDs, LDRs, op-amps, transistors, DC motor (without encoder), analog temperature sensor.
So no ardunio. The circuit must be analog. That means more than a few opamps probably.
My biggest confusion is how do i generate a simply adjustable duty cycle with only opamps or other allowed parts? And probably i will need to convert it to DC (depending on the duty cycle.). How do i do that?
Any help is welcome really.
EDIT 1 : Working on it. Will update asap.
The project is schematically as follows :
Sensing Unit -> CONTROL UNIT -> Heating and Cooling Functions.
Temperature Adjustment Unit ---> CONTROL UNIT ->
Basically sensing unit (operating with an LM 35 chip) detects the outer temperature and yields a dc voltage directly proportional to temperature in celsius (eg. for 27 degrees of ambient temperature, it yields 270mV)
Temperture Adjustment unit is where input occurs. User sets (using buttons or whatever) a square wave with a specific duty cycle so that %0 duty cycle wil be evaluated as -50 celsius and %100 duty cycle (simply a DC signal) will be interpreted as +50 celsius. This data will be our desired temperature.
These two pieces of information are then gathered at the Control Unit. This thing compares the two , and if it is hotter than desired, it will run a DC fan (how effective, right? ) and if it is colder than expected it will give current to a stone resistor. The system will stop running when the diffeence between desired and ambient temperatures are less than or equal to 2 degres.
Even though it all may seem a little simple i am very confused. And unfortunately, the material we can use are limited to : (directly copied from the project file) You are allowed to use +/-25 V output of DC power supply and you may use any types of resistors, capacitors, inductors, diodes, LEDs, LDRs, op-amps, transistors, DC motor (without encoder), analog temperature sensor.
So no ardunio. The circuit must be analog. That means more than a few opamps probably.
My biggest confusion is how do i generate a simply adjustable duty cycle with only opamps or other allowed parts? And probably i will need to convert it to DC (depending on the duty cycle.). How do i do that?
Any help is welcome really.
EDIT 1 : Working on it. Will update asap.
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