[HELP] Condenser Pump system design

[Musa]

Hi everyone, I'm new to this community and I'm glad to be here.

Long story short: I'm a second year Elec Student (BscEng) and I've been struggling with a project for over a week now.

 

In short, I have to make a Condenser pump subsystem that will do the following:

 

1. Sense the temp of water at two distinct temperature points (22deg C and 30deg C)

2. If temp goes over 30degs then a red LED lights up and a fan motor is turned on (this motor fan can be symbolised as a relay)

3. If temp is around 22degs (so virtually lower than 30degs) a green LED will light up and imaginary water will be poured into the condenser (this water-pouring stage is also represented by just a relay).

4. The pump relay must only start when the temp is at 22deg

 

What I have done so far:

1. Made a circuit with only the LEDs and one LM35 temp sensor and used the LM741 op-amp as a comparator (I'm still not too clear about this concept). The circuit worked but both LEDs were on and even if I varied a 10Kohm potentiometer it didn't seem to dim either of the LEDs.

2. Tried simulating the circuit on Multisim 13 setting the LM35 sensor as a resistor (because I couldn't find the sensor component on multisim) but no success.

 

I'm still a relative beginner to Electronics (I'm only in my first semester of my first electronics course) so any hints and guidance from the veterans of this remarkable trade would be really appreciated. In essence I look forward to learning new things during this project instead of just completing it blindly and getting a good grade. So please help me and direct me in all the right paths so I may hopefully become like all you experts here.

 

Additionally, I would like specific help with the following questions of mine:

a. How does a comparator work?

b. Could I use a logic gate to make this subsystem? (I haven't learnt that yet in electronics too but I've done it in A-level CompSci)

c. How to connect an 8-terminal relay to a breadboard circuit?

d. Will I have to make two identical circuits for this project in order to read the two distinct temp values?

 

PS: I have attached a copy of the Project brief for this subsystem to clarify any points I may have misinterpreted

[Hari Prasaath K]

Hi,

I would suggest you to go for microcontroller for your project which can be controlled through codings. Have you used any microcontrollers before.

[Author]

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