I need help with a car anti-theft device circuit schematic

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Discussion Overview

The discussion revolves around designing a circuit schematic for a car anti-theft system intended to disconnect the car battery shortly after an alarm is triggered. Participants explore various approaches, challenges, and considerations related to electronic engineering and security mechanisms in vehicles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant expresses uncertainty about how a circuit could function if it disconnects its own power source, suggesting that a high-current relay would be necessary for the battery disconnect.
  • Another participant proposes that there are methods to disable a vehicle without completely cutting off the battery, asking for specific requirements of the project.
  • A participant mentions the need for a reset mechanism for the system to allow the car owner to regain functionality after a theft attempt, questioning how to prevent a thief from exploiting the same reset method.
  • One participant shares a historical perspective on vehicle anti-theft measures, referencing a past program that offered devices to disable ignition and unlock mechanisms, highlighting the evolution of anti-theft technology.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best approach to designing the anti-theft system. There are multiple competing views regarding the feasibility of disconnecting the battery and the implications of such a design.

Contextual Notes

Participants express varying levels of experience with circuit design, with some indicating a lack of familiarity with complex schematics. The discussion includes assumptions about the functionality and security of proposed systems without resolving these uncertainties.

Who May Find This Useful

Individuals interested in electronic engineering, circuit design, vehicle security systems, and those working on related school projects may find this discussion relevant.

BoatingJoe
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Thread moved from the technical forums to the schoolwork forums
I'm working on a school project and I have to find and/or make a circuit schematic to a car anti-theft system that will disconnect the car battery shortly after the car alarm goes off. I am new to the electronic engineering field but I can differentiate a few different components on a schematic diagram but I would say that I can navigate simple schematic diagrams with some ease.
 
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BoatingJoe said:
I'm working on a school project and I have to find and/or make a circuit schematic to a car anti-theft system that will disconnect the car battery shortly after the car alarm goes off. I am new to the electronic engineering field but I can differentiate a few different components on a schematic diagram but I would say that I can navigate simple schematic diagrams with some ease.
Welcome to PF! :smile:

But if your circuit is powered by the battery, won't it stop working when it cuts off its own power? And the battery circuit is a very high-current circuit, so it will take a monster relay to do the disconnect. Can you post the full text of the project assignment? Thanks.
 
I feel safe throwing out some hints. Yes the battery is a very high current source but there are ways to disable a vehicle without disconnecting the complete battery. The question is: Is there a specific requirement?
 
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Averagesupernova said:
I feel safe throwing out some hints. Yes the battery is a very high current source but there are ways to disable a vehicle without disconnecting the complete battery. The question is: Is there a specific requirement?
Well we don't have a specific requirement since we have to come up with a product that has something to do with security and if we make something that already exists, we have to improve it in some way. My group decided with preventing the car from being hot-wired and the whole car being stolen and we want to disable the power completely.

I have not made a circuit schematic with anything but a DC power source, resistor, and LED light. So I have no clue how to do anything complex.
 
berkeman said:
Welcome to PF! :smile:

But if your circuit is powered by the battery, won't it stop working when it cuts off its own power? And the battery circuit is a very high-current circuit, so it will take a monster relay to do the disconnect. Can you post the full text of the project assignment? Thanks.
"won't it stop working when it cuts off its own power?" Yeah, that's the idea. After a certain amount of time of the car alarm going off, I don't know how but maybe some kind of IC will trip some kind of switch— like a circuit breaker— that would have to be manually reset after the device system cuts the power.

"Can you post the full text of the project assignment?" Since I'm still in school, so the assignment is for the class to design something that has to do with security and my group decided to prevent the car itself from being stolen. We thought of a suicide circuit that can just disable the car battery so the car cannot be hot-wired and started.
 
BoatingJoe said:
so the assignment is for the class to design something that has to do with security and my group decided to prevent the car itself from being stolen. We thought of a suicide circuit that can just disable the car battery so the car cannot be hot-wired and started.
Well, think this through a bit farther (you may have already done so)... Somehow the car owner needs to be able to reset the system so they can still drive their car after the failed theft attempt. But what will prevent the thief from using the same reset mechanism? If it's just a mechanical reset switch under the hood, the thief will be able to pop the hood and reset it just like the car owner wood.
 
Back in the 80's our Manitoba provincial gov't owned Vehicle Insurance company (Autopac) had the best service and non-profit rates and gave rebates year-end, if they made a profit. I wish we had this in Ontario.

Then due to rising car thefts but modern vehicle anti-theft RFID's but before modern theft tools, they gave a free offer of a wireless Interrupter that would disable the front hood unlock and ignition supply. Older vehicles were eligible.

Now they have cheaper version that just cuts off the fuel pump. So it must be installed where it is hard to guess.

https://www.amazon.ca/dp/B091TPXY3D/
 
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