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Reed switch

Netrack

Sep 15, 2016
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Hi and apologies but I am a complete noob. I am trying to build a circuit with some surface mounted reed switches (3-5) and a simple electric door lock powered by a small 12v battery. I have found a battery that is rated to 1.2 amps and the door lock draws 600ma but I cannot find any reed switches in the UK that I can use as they all seem to be rated for 500ma max. I was after the type with screw connectors rather than those that fit breadboards.

The door lock can be found here https://www.amazon.co.uk/gp/aw/d/B0...ecure+bolt&dpPl=1&dpID=41EJ4YunO9L&ref=plSrch

Any help would be greatly appreciated

Thanks
 

duke37

Jan 9, 2011
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You should use a low power reed relay and use a transistor as a switch.
The transistor should be capable of 1A and the base should be driven by a current of about 20 to 50mA.
If you use a fet, the gate should be raised to 12V to turn it on and a resistor to earth to turn it off.
 

Harald Kapp

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That black wire labeled "-12 VDC" should be 0V, which is the negative pole of the +12 V source, shouldn't it? With only one 12 V battery there wil be no 112 V available, nor is it necessary.
 

Minder

Apr 24, 2015
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The OP mentions SWitches, so they would either have to be NC type or OR'd N.O.
Ones that have terminals are usually the window/door alarm system types and are N.C. all in series, (NAND'ed).
M.
 

Externet

Aug 24, 2009
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Not only colorful, but Edd invests time and effort to provide good pleasant responses to members.
(-12) should be interpreted as the negative of 12V. A pull-off resistor at the base should be convenient to add.
73 !
 

73's de Edd

Aug 21, 2015
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Yep . . . .only one 12 VDC supply involved, and those are referenced as being the two positive and negative terminals of same.

( Those two lines above were created immediately after Sir Haralds comment and have been carried forward in page cache memory of the laptop that they were composed upon. So I now enter that past neglected " Post Entry" and its info is now falling into place . . . 3 entry's later. )
 

Minder

Apr 24, 2015
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I always tend to use COM instead of GND to avoid the Earth confusion.
We tend to lable the power e.g. 12DC+ 5vdc+ etc but neglegt the minus side..
Often the commons are usually simple notation instead of the same practice as 12vcom, 5vCOm etc.
M.
 

Netrack

Sep 15, 2016
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Thanks for all the replies very much appreciated! As I mentioned I am a complete noob! What is the tip120 on the diagram and what does this do? I will no doubt have more questions but it might become clearer to me when I understand this bit of the circuit. I figured the switches would need to be NO. As this will be in a cabinet and the switches will need to be spaced apart (will draw something to explain) I guess I could use switches on bread boards but would need separate breadboards for each switch and connect with wires....
 

73's de Edd

Aug 21, 2015
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.

Netrack. . . .

Would it now be logical . . . to consider your other aspect, in the the operation of the solenoid.
Of course that would be the simplest Neanderthalic crypto like consideration of the utilization of 1 through 3 reed switches for the activation of the solenoid.
That would be the assignment of numbers one through nine to a " keypad " with that selective area being all cramped within the closeness of a hand span.
Then some dope comes up and starts pressing any and all inclusive entry possibilities . . .for the rest of his life . .
In hoping to crack the code of the opening of the lock .
In reality the actual operation of the lock is dependent upon from 1 thru 3 series wired reed switches that are being physically located, CLOSE behind their select numbers to be activated by a neodymium magnets proximity of being placed above them.
I max out at three, because I can only visualize the manipulating / positioning of three magnets at one time .

73's de Edd
 
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