project help? garage door sensor

[onion456]

show me a sensor that use an nand gate

hi

i have a project thats been brewing in my head for kind of a while, my next door neighbors are fairly lax about keeping their garage secured 100% of the time, and they get ripped off because of it. i was thinking of something like a garage door sensor, where if someone were to cross an infared beam, it could sound an alarm inside the house.

i priced out regular old genie garage door sensors and they are a bit pricey ($25), i was wondering if anyone knows of any other options, as i would want to cover 2 doors (one standard doorway and one garage door). i could probably struggle through the alarm circuitry myself if i could solve the sensor part of it.

any suggestions welcome =) thanks

 

[flatulent]

garage door sensor troubleshooting

Considering the economic loss cost of the theft, the $25US seems a small price to pay for preventing loss. Another way is to have a timer that closes the door at a specific times. An even lower cost method is to have the persons close their door when they are not exiting or entering their garage with their car (or motorcycle or bicycle).

This reminds me of the overpriced electronic reminder to notify people that it time to brush their teeth or eat their dinner or go to bed.

 

[onion456]

schematic garage door safety sensor

no doubt there.. on both points =D

but, it also serves the purposes of giving me something to do and furthering my fledgeling understanding of circuit design, as well as allowing them to live the way they want to live. so im looking into it, and if options are available, i may take a stab at it. im just a tightwad, i dont want to drop $50 on just the sensors if there are other options.

 

[flatulent]

electronic project doors with help of sensors

There are several ways to sense that the garage door is open. The lowest cost one is a mechanical lever arm that is moved when the door is up or down. This can close an electrical contact. Then you use a DC circuit to show if the switch is closed or open.

 

[pakitos]

how to rig garage door sensors

can you give me more details?
you want to sense that the door is open>
or you want it to be closed too?
or you want to sense that there was an intruder?

 

[onion456]

genie garage door opener model 555 schematic

thanks...

they like to leave thier garage door open- the garage is sortof their 'party spot'. they also use it for minimal storage of stuff. they just like to hang out in there and drink beer, listen to music, and be mellow. they deserve to be able to do that without someone ripping off thier stuff.

i was thinking, since an automatic garage door opener has the sensors to tell if something is in the way, the same sensors could be used to detect if something or someone has crossed the plane into thier garage. essentially a motion detector, but not. (i find motion detectors to be somewhat unreliable?) just detect if the light path between sensors has been interrupted. seems simple enough...

so i was just wondering if any other sort of light source/detector might exist that is less expensive than commercial garage door sensors, and is powerful/precise enough to detect a blockage of light (visible or non, preferably non) from like 8' away (distance across opening of garage door). i could just rig something up to ring a bell or whatever if the sensing of light is interrupted, so if they are in the house and the bell rings, they know someone is there.

make sense?

 

[pakitos]

motion used a garage door sensor

ok, so you just want to know if someone is there.
your only point of interest is the cost?
Do you know electronics?
Can you connect a circuit?
There are several ways. I will put them in order from least expensive to most

Simple Switch
Infra Red Light
Ultrasonic motion detector
microwave motion detector

I think the first two are ok.
Decide and let me know. To see where you want to put them. Do not worry I will help you with the schematic.
Good Luck

 

[onion456]

motion detector sensor garage door

welp... my experience is this:

ive been an electronics technician for 17 years, troubleshooting and repairing. im very experienced with surface mount rework and soldering in general. However, i have very very minimal experience designing circuits. i would love to get into that and am currently enrolled in school to eventually obtain my EE.

so yes, i can connect a circuit. do i know electronics? thats debatable, but i would say yes, to a degree.

i dont see how a simple switch would work. i could definitely see an infrared system working in this application. not too sure about the last two options =)

as far as where to put them, imagine a normal automatic garage door sensor- they are about ankle high on both sides of the garage door, focused on each other. if anything is between the two sensors, the garage door will not close. i think my system will put the sensors about waist high, as they have many cats that are in and out of the garage all the time. so. someone walks in the garage, breaks the path of light bewtween the two sensors. we design a circuit that will ring a bell when this happens. itll be fairly unobtrusive, as they themselves will be in and out of thier own garage all the time, it rings a bell, no big deal. but when they are both inside the house, and the bell rings.... that tips them off that someone is in thier garage.

so i dont know what the sensor feedback looks like, but im assuming that if the light and detector are connected (light being detected), that the sensor output will be an active high signal. so if someone blocks the path of light, the detector output will go low. so im thinkin that will be fed into a NAND gate or something. so 2 active highs equals a low. if either input to the NAND goes low, the output of the NAND goes high. and obviously this high output will enable the alarm, and i havent really worked that out yet =)

and by bell... that could be any non-annoying beeper or whatever. they are going to hear it go off probably all the time, so the least annoying, the better. maybe something that sounds like a digital watch alarm, for about 2 seconds. or a bell. or whatever. =D

Thanks for your help

 

[pakitos]

garage door opener sensor schematic

Let me explain how the switch may work.
There are pads like carpets (usually used infront of big machines like wood cutting. If someone walks on the machine will turn off). You can use one of those making it is easy. To prevent it from triggering you have to do it in a way it needs more weight than a cat's.
To do the circuit you just need a 555 timer to make the buzzer beep for a certain time (with RCs). Then a transistor and a buzzer.
This is the cheepest method if you do not know how to connect it Ill draw one for you.
If you prefer more complicated designs I can help you in that too.
Good Luck