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Hi,
I used 3 555s
1. Monostable, delay producer.
2. Simply instead of inverter, because next one wants to be negative triggered.
3. Produces pulse of certain width.
In practice i used magnetic switch and 741 as comparator, because there is no zero condition at switch.
See screenshots...
Hi,
I'd like to create some simple alarm, that will call me when the door is open. I found magnetic switch (normally closed) at home, old cellular, bunch of resistors/capacitors and some 741 and 555 a relay, optocoupler.
What i'm trying to do is to use speed dial function of my phone, "pushed"...
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