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Thread Starter

electronics123

Joined Feb 22, 2020
35
Design Brief
A family wishes to be alerted to the amount of energy they are using
Develop a system which monitors the lights in four rooms of a house and displays a warning when at least three of the lights are switched on
Do notmake any electrical connection to the mains supply

The Requirements

I need help with designing the circuit and test procedures as well as calculation

I am not allowed to use programmable components
The organisation has required the use of at least four logic gates, one input subsystem to provide a digital signal for logic gates an output subsystem, funcitonal intergration and power only from batteries or low voltage power supply unit(maximum 12 volts)


I. HAVE NO PRIOR KNOWLEDGE TO ELECTRONICS
HELP WOULD BE MUCH APPRECIATED

MOD NOTE: E-mail address removed to prevent spam.
 
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WBahn

Joined Mar 31, 2012
25,274
What are your thoughts on how to detect that the light is on in a room and produce a logic-level signal in response?

What kind of logic could you use to produce a logic HI when at least three out of four inputs is HI?
 

Thread Starter

electronics123

Joined Feb 22, 2020
35
It's one of the first things you should have learned in a digital electronics course.

Googling "logic HI" yields a bunch of results, some of which are extraneous, but very early in the results list is the following Wikipedia page:

https://en.wikipedia.org/wiki/Logic_level
It is a subject i take in school, however, the teacher does not do much and simply hands us the notes and many of us do not understand
 

WBahn

Joined Mar 31, 2012
25,274
When 3 of the inputs are high, the logic level will be high
When ALL three of the inputs are HI, the logic output will be HI.

How does that help you address your problem of generating a logic HI when ANY three out of four inputs are HI the output will be HI?

Using a 3-input AND gate is a start, now try to take the next step along that path.
 

Thread Starter

electronics123

Joined Feb 22, 2020
35
When ALL three of the inputs are HI, the logic output will be HI.

How does that help you address your problem of generating a logic HI when ANY three out of four inputs are HI the output will be HI?

Using a 3-input AND gate is a start, now try to take the next step along that path.
ANY three out of four inputs are HI as long as 3 are high the circuit should display a warning, hence if the output is HI then a buzzer/LED light should light up
 
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