Hello everyone. This is my first post. In browsing around a bit today I thought that this community would be a good place to ask a question (or two) about a project I've been dreaming up for a while now.
For a bit of background, my only experience with circuits (besides minor home repairs) is from a couple of under-grad classes I had to take as part of my mechanical engineering degree. In other words, I know enough to recognize a term or two, and as far as I know, Ohm's Law can solve every problem know to man about electricity.
So, here's what I've dreamed up...
I want to build a secret door to the space under our stairs. After watching a show on HGTV, I've gotten a bug to use magnets as keys to unlock the door. I've attached a pdf of the simple circuit I've come up with. Basically S1 would be a magnetic switch in the door to turn everything off if the door is open. S2 is a normally closed switch that could be opened up to re-set the circuit. S3 is some sort of switch to turn the circuit off if it is left on too long. Step one would be triggering reed switch S4 with a magnet. This would open up the first transistor (R2 would keep the circuit from frying). Then S5 would be triggered (again with a magnet) to turn the solenoid on which would unlatch the door. Once the door is unlatched S1 would open up, turning off the circuit.
So, my questions are: is this a practical and workable circuit? If not, what would you recommend for something like this? What could I use for S3? I was thinking a thermal switch (replaced one in a blender once, boy did that prove the little missus wrong for once!) Or would some sort of timer be easier/more reliable?
Thanks for any help you can offer!
Dan
For a bit of background, my only experience with circuits (besides minor home repairs) is from a couple of under-grad classes I had to take as part of my mechanical engineering degree. In other words, I know enough to recognize a term or two, and as far as I know, Ohm's Law can solve every problem know to man about electricity.
So, here's what I've dreamed up...
I want to build a secret door to the space under our stairs. After watching a show on HGTV, I've gotten a bug to use magnets as keys to unlock the door. I've attached a pdf of the simple circuit I've come up with. Basically S1 would be a magnetic switch in the door to turn everything off if the door is open. S2 is a normally closed switch that could be opened up to re-set the circuit. S3 is some sort of switch to turn the circuit off if it is left on too long. Step one would be triggering reed switch S4 with a magnet. This would open up the first transistor (R2 would keep the circuit from frying). Then S5 would be triggered (again with a magnet) to turn the solenoid on which would unlatch the door. Once the door is unlatched S1 would open up, turning off the circuit.
So, my questions are: is this a practical and workable circuit? If not, what would you recommend for something like this? What could I use for S3? I was thinking a thermal switch (replaced one in a blender once, boy did that prove the little missus wrong for once!) Or would some sort of timer be easier/more reliable?
Thanks for any help you can offer!
Dan
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