[satanicoo]

Hello there!

Glad to make again this kind of questions on a water-cooling forum, also resourcefull on other subjects!

So what's happening?
I am designing an electrical system for a school project, And i am getting troubles since it is somewhat vague on the ICs we have to use.
They only say "i want something that does this", and they give us some ideas on how to do it and what ICs to use.
So, i will post it here, hoping to have some help from bigben and others electronic
knowledgeable people around.




Introduction:
The students are asked to implement a circuit that controls proportionally light itensity.
The goal is that this circuit reacts inversely to the ambient light. The possible measurable delta should be previously measured with a luximeter (?)

Task 1:
It is pretended that you build an Circuit to power a 24V/24W light. You should use a PWM modulator, sugested CI TL494.
The medium valor of the actuation current should be directly proportional to a variable input tension between 0V and 5V.
The result signal should go trought an optic isolation circuit, using CI TLP521,before it acts on the transistored circuit.

Task 2:
Here you should develop a signal conditioner for an LDR, that will measure the ambient light. The output of the circuit should present a signal between 0V and 5V, correspondent to the max ambient light. Should also be developed, if necessary a linearization circuit. (??)

Task 3:
Now implement a Analog/Digital converter to acoplate to the output of the circuit built in task 2. This should be based on a tipical mount of with CI ADC0801.

Task 4:
Develop a proportional control circuit to stabilize the luminosity at half the maximum luminosity at the Lab.
Thi circuit should be based on operational amplifiers and should have 2 imputs: reference one (a potenciômeter) and the other relative to the total output of the conditioning of the LDR.
The output should be adequated to the actuation of the circuit developed on Task 1. (actuation circuit of the power resistors).

Task 5:
Now interconnect all the circuits. You may need to do some ajustments and you should verify the global functioning, and finally, Some measuremetns snd conclusions should be drawn.
The outputs of the A/D converter are only for visualisation, so they aren't part of the control system.

Task 6:
Here you should develop a D/A converter. It should be based on the CI DAC0800, and the imputs should pass previously on a group of 8 digital buffers, wich will serve as an interface to the digital outputs of a data acquisition board (to use more in front). The output should vary between 0V and 5V and is only for visualization.

Task 7:
Here, an adaptation should be made to the developed system, so that a Pc control can be made.
The acquisition board DT2801 should be used ( to adquire an analog imput and for the exteriorization of 2 outputs, one analog and the other 8 bits digital).
The software to use will be the Labwindows, to program a software to implement the adquisition and control of the luminosity.


UFF! thats it! I will post later the PDFs and what i have done so far.