Can anyone help me with this task plz
From the physical point of view, an alarm loop (AL) is an electrical circuit that connects the device with detectors (sensors) using wired connections. The main task of the alarm loop is to ensure the detection of the fact of detector actuation. The loop is connected to the resistance meter via the terminals located on the control panel board. The microprocessor measures the electrical resistance of the entire loop circuit and, based on its value, decides whether the detector has been triggered or not.
Any detector can be represented as an electrical contact, which, when triggered, changes its resistance dramatically: it becomes either closed (contact resistance is zero (NC)) or open (contact resistance is infinity (NO)).
From the physical point of view, each loop has different variants of wiring diagrams, which the user selects. The wiring diagram depicts the detector contacts, resistors, and other components that ensure the operation of the alarm loop.


Main task:
It is necessary to depict an electrical ring/chain (as in the connection example) on which there will be 2 loops (loops/sensors/keys) with the correct type of connection (series and parallel) and understand when we have a change in the circuit, namely, whether there is a current when any of the loops (loops/sensors/keys) is triggered
Image of the loop connection:
1. with 2 normally open (NO) sensors. By default, the current does NOT flow through the circuit, and when triggered (closed), it does
2. with 2 normally closed (NC) detectors. By default, the current flows in a circuit, and when triggered (opened), it does NOT flow
3. with mixed contact activation, where there are normally closed (NC) and normally open (NO) sensors
4. with 2 normally closed (NC) sensors and a 5 kΩ resistor (the circuit resistance is also 5 kΩ)
5. with 2 normally open (NO) sensors and a 5 kΩ resistor (the circuit resistance is also 5 kΩ)

The resistor is used to prevent sabotage because if the circuit to the loops/sensors is shorted, then the triggering will not be detected. The resistor must be placed in such a way that we can understand when the circuit is shorted to the loop/sensor (resistance does not correspond to the expected value (resistor value))
I have to draw the serie version and the parallel respecting the example given plz can anyone help me do that Im new in electronic

 

i did this but i think im missing something , and also I should do the parallel cases two?

 

i did this but i think im missing something , and also I should do the parallel cases two?

Yes, you are missing something

Fig 1. No. In this setup, UNLESS both sensors operate, you will get no "input". The sensor contacts should be in Parallel.
Fig 2. Yes. That's how it should be.
Fig 3. No. You cannot combine a NC and a NO sensor to the same input.
Fig 4. is fine, IF you need a Resistor. But this is not how a "Pull Up" or a "Pull Down" resistor is connected.
Fig 5. No. Ssame as Fig 1, except for a series resistor.

Consider the Sensor contacts as a Digital 0 (NO switch) and Digital 1 (NC switch).
For sensing any change, you will need to OR the sensors (NO switch) and AND the sensors (NC switch).

 

It is necessary to depict an electrical ring/chain (as in the connection example) on which there will be 2 loops

hi @ilyass9996

Is this question a Homework or College assignment?

Moderation.

 

When resistors are used in a "supervised" alarm loop they are not "pull up" or "pull down" they are placed in the loop in such a way as to detect any sensor tampering.

Alarm Circuit Supervision – Why You Should Care

 

When resistors are used in a "supervised" alarm loop they are not "pull up" or "pull down" they are placed in the loop in such a way as to detect any sensor tampering.

Alarm Circuit Supervision – Why You Should Care

Yes. Because if there's (for instance) a 10 volt line going to the sensor, the resistors create a voltage drop. Inside the panel there is a window comparator which is looking for (for instance) between 6 volts and 4 volts. If someone shorts the sensor the voltage will go to 10 volts and trigger an alarm. If they cut the wires the voltage will drop to 0 volts and trigger an alarm. If the door is opened when the alarm is armed the voltage will rise above the set window voltage, this example, the voltage might rise to 9 volts.

It's been about 40 years since I did any alarm work and I don't recall exactly how it was done, but this (which is probably containing an error or two) will give you an idea why the best choice is using an NC Series/Parallel setup. Spidey has it right with the link. If you didn't look at it or are having trouble understanding what you're reading - just ask for clarification.

 

Try the Falstad circuit simulator. It's great for visualising and solving problems like this. I put together a basic simulation to get you started. Open the simulator then click import text to import the code below. https://www.falstad.com/circuit/

For your images, it makes sense to display them in terms of current. KCL tells us that currents entering a node equal currents leaving a node. In this case, each resistor drops the full 10V and contributes exactly 10mA to the circuit. Provided the switch is closed, these current add to 20mA at the output.

You are probably familar with binary states which is pretty much the same idea here. But instead of defining "0" as 0V and "1" as 10V, I've defined 10mA as "0" and 20mA as "1". If I get any other current reading at the output, I'll know something is wrong because I didn't define those states.

Keep in mind this can all be done with voltage or resistance definitions but I'm choosing to work in terms of currents. You might need to convert currents to voltages in order to sample them but I leave that to you to figure out. You can read more about current loops here: https://en.wikipedia.org/wiki/Current_loop

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