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Alarm system from scratch

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Hi Zach,
Your PNP transistors are upside down. The collector of a PNP must be negative to its emitter. Then they need a base resistors or their forward-biased junction will be like a dead short when the NPN transistors turn on.
I forgot to mention that, its not my fault, SWCAD III does that!! :roll: . And yeah, i forgot to draw in that base resistor. Gotta put those diodes in there too.

Im not really planning on actually making this circuit, it was sort of representative of what I want to do. I know that there is a better way of doing it that is simpler and won't require as much room on my board. Can anybody think of any ways?

I might not even have to order any of this stuff, I have a friend whose dad used to be heavily into electronics but is not anymore. He has a whole SHOP full of electronics junk . . . FOR ME!!!!! im so excited, figured i would share . . .
 
I have pretty much all the plans drawn up. It takes me a while to make circuits because i dont always have a lot of free time.
 
Cant say that i did. there are only two sensors that i am actually going to make, a laser break and IR break sensor. I mentioned earlier that i am using the security system that came with the house.
 
GTA, ur obsessed with that website, ive seen you recommend it to two other people :lol:

I dont think i need any other systems :lol:
 
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Well that is one of my signature's, plus that website is great, I have built a lot of thing's from that website.


:D
 
if you like that one, try discovercircuits.com They have even more schematics, a lot more :lol:
 
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I have been to all those type's of website's including that one, but thanks for the tip.
 
Alright, im stumped here. I somehow need to make a way for my system to turn on and off automatically, like turn on @ 11:00PM and off @ 6:00AM.

Basically what I need is a signal that will stay on for a certain amount of time (alarm automatically on) and then for that signal to turn off (alarm automatically off). I was thinking of somehow incorporating a wristwatch alarm into the system, since I can set the time, and the alarm time very easily. I have a wristwatch that has two alarms, one for on, and one for off :lol:

Im up for using a PIC as well, I might as well start now :lol:
 
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Try that website I gave you and look at the timer's and you might not even have to modify it.
 
how about those boxy thingnys that you plug in the wall and set the on an off time for an device that is conected to it. (its not the chepest way but cod do)

meaby an PIC whith an real time clock (to have an acurant clock) an small LCD (to show the time,and for easyer setings) and some buttons (to set the time)You can also add an small Li-ion backup batery so it keeps the time wen the power is gone and the PIC wod store the alarm times in its EEPROM (whith a litle moreprograming you cod also make it thurn on/off at difrent times at difrent days of the werak)

the burgler seing the laser shod be only the problem in fog or even beter use an IR laser (cheap cameras whith no IR filter see the IR ligth as white but our ies see it as nothing)

you cod also use an high power CO2 laser (it emits IR light and is used for cuting metals!!!) that wod fry the one that intersects it

i wod like to see how it comes out! (post some picture of it)
 
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Ya but you would still have to set the timmer every day, I would think that it would be best to go with searching the web and finding stuff that people already did.
 
I forgot about that GTA :lol: Maybe I will end up using somethng off that website.

Can't search right now though, ill let ya know what i found.

Ill definitely post pictures and schematics of this thing, seeing as it is my first really big project that i have designed myself (mostly)
 
Can you make it so that when a burglar breaks the laser's beam, a camera takes a pic of the laser cutting off his legs? :lol: :lol:
 
I'm working on an IR beam break system right now.

I have modulated an IR led with a 25/26kHz square wave from a 555 timer. I'm not sure how to make a filter for the receiver though. I would like to make a passive RC filter. The square wave turns the LED on during negative pulses.
 

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Hi Zach,
A simple coupling cap feeding a resistor to ground will make a highpass filter so that 120Hz from lightbulbs doesn't activate the IR receiver. A passive bandpass filter would be lousy and have a high loss.

I don't remember the schematic of your IR receiver that might not respond as high as 25kHz anyway. Many people around here think they can use a low-bandwidth LM324 or LM358 opamp for high frequencies. :(
 
Its not only the 120hz. Its the sunlight also. The receiver will be in direct sunlight.

Im sure I could make the frquency lower.
 
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