Showing posts with label protection. Show all posts
Showing posts with label protection. Show all posts
Sunday, October 5, 2014
LM317 Overvoltage Protection Circuit
It is a voltage regulator that allows a 6v carriageable accumulation to be acquired from the 12v car battery. You can add a 6.2V zener diode and a LED to acquaint you back the ascribe accumulation is overvoltage. If you could acquisition a broadcast that would accomplish from 6.2v appropriate up to 12v that you could affix in such a way that if over voltage occurred, again the broadcast would automatically about-face off the achievement preventing accident to any affiliated equipment.
Such a broadcast would be absolutely difficult to find, so I advised this, it is a simple two transistor ambit which will about-face off the achievement should the voltage accession aloft 6.2v (this can be afflicted by selecting a altered amount of zener diode ).
Components are as follows:
ZD1 =3D 6.2v Zener diode (you can change this to any value, the ambit will about-face off the achievement if the ascribe voltage raises aloft the amount of the zener diode)
R1 = 1K Resistor (this can be of any ability rating, it carries actual little power)
R2 = 1K Resistor (this can be of any ability rating, it carries actual little power)
T1 = Low ability NPN Transistor (BC108 or BC547 will do fine)
T2 = NPN transistor transistor able of switching the accessories you are active (BFY51 or BC140 can about-face 1 Amp, which is the best the voltage regulator ambit can handle)
It is appropriate to analysis this ambit with a voltmeter, boring accretion the voltage on the regulator ambit and accomplish abiding that this ambit switches off the achievement back the amount of the zener diode is reached, afore active in your big-ticket equipment. This ambit is advised to be acclimated with the voltage regulator acquaint by Matthew Hewson, my overvolatge add-on ambit is apparent with the aboriginal below:
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Such a broadcast would be absolutely difficult to find, so I advised this, it is a simple two transistor ambit which will about-face off the achievement should the voltage accession aloft 6.2v (this can be afflicted by selecting a altered amount of zener diode ).
Components are as follows:
ZD1 =3D 6.2v Zener diode (you can change this to any value, the ambit will about-face off the achievement if the ascribe voltage raises aloft the amount of the zener diode)
R1 = 1K Resistor (this can be of any ability rating, it carries actual little power)
R2 = 1K Resistor (this can be of any ability rating, it carries actual little power)
T1 = Low ability NPN Transistor (BC108 or BC547 will do fine)
T2 = NPN transistor transistor able of switching the accessories you are active (BFY51 or BC140 can about-face 1 Amp, which is the best the voltage regulator ambit can handle)
It is appropriate to analysis this ambit with a voltmeter, boring accretion the voltage on the regulator ambit and accomplish abiding that this ambit switches off the achievement back the amount of the zener diode is reached, afore active in your big-ticket equipment. This ambit is advised to be acclimated with the voltage regulator acquaint by Matthew Hewson, my overvolatge add-on ambit is apparent with the aboriginal below:
LM317 Overvoltage Protection Circuit
Friday, August 22, 2014
OBD Vehicle Protection Wiring diagram Schematic
vehicle immobilisers are fitted as standard to modern cars and heavy goods vehicles. Anti-theft mechanisms have become more sophisticated but so have the methods employed by crooks. Nowadays once the thief has gained access to a vehicle they will most likely use an electronic deactivation tool which seeks to disable the immobiliser, once this has been accomplished a blank transponder key/card can be used to start the engine. In many cases communication with the immobiliser is made using the OBD-II diagnostic connector.
Although the OBD-II protocol itself does not support the immobiliser, the vehicle manufacturer is free to use the interface as neces-sary for communication, either the standard OBD-II signals or unused pins in the OBD-II connector (i.e. those undefined in the OBD-II standard). Using one of these pathways the immobiliser can usually be electronically disabled.
OBD Vehicle Protection Circuit Diagram
This may be unsettling news for owners of expensive vehicles but when professional car-thieves call, armed with the latest OBD-II hacking equipment this simple low-cost low-tech solution may be all that you need. The idea is ver y simple: if all connections to the OBD-II connector are disconnected there is no possibility for any equipment, no matter how sophisticated to gain access via the vehicle’s wiring.
The OBD-II connector is usually locate d underneath the dashboard on the passenger side; once its wiring loom has been identified a switch can be inserted in line with the wires. The switch should be hidden away some-where that is not obvious. In normal opera-tion you will be protected if the vehicle is run with the wires to the socket disconnected. Make sure however that you throw the switch reconnecting the socket before you next take the vehicle along to a garage for servicing or fault diagnosis.
The diagram shows the ISO K and ISO L wires switched. To cover all bases it is wise for every wire to the socket is made switchable except the two earth connections on pins 4 and 5 and the supply voltage on pin 16. Almost ever y vehicle manufacturer has their own method of vehicle immobilisation, by disconnecting every wire it ensures that no communication is possible (even over the CAN bus). Now the innermost workings of your vehicle will be safe from prying eyes. When a hacker plugs in a deactivation tool it will power up as normal but probably report something like ‘protocol unrecognised’ when any communication with the OBD port is attempted.
Author : Florian Schäffer - Copyright: Elektor
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