Nice! I need to get one of those bags!

 

I suppose I should clarify what I meant then.

I'm not concerned with what happens after disconnect. I am concerned with the output attempting to send a signal to the lock actuator every time the sensor crosses the 5v threshold.

You already made that clear. I'm working on it. It's called a lock-out or a latch-out. That kind of circuit will only keep the circuit from sending a second pulse until you disconnect the power. After you disconnect the power, the circuit can't send a second pulse because it doesn't have any power.

 

I see where the confusion is coming from now. When I say "lock actuator", I am referring to a physical locking mechanism to prevent opening something, not an electronic component.

 

I don't think I'm confused. You keep saying the same thing: Threshold = pulse, and stop. Refuse to start until power has been stopped and re-started.

 

It's coming along. Feel free to put this in MS Paint and build an idea, tracecom.

Electric door locks sound pretty strong, so I'm going to give it a relay...right after I look at the datasheet and remind myself how a 555 works. How about you go see if you can find a single comparator?
I'm going to put a start-up delay on the reset pin so it doesn't get hinky when it gets plugged in.

 

LM311 should work.

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_23528_-1

 

and about 40 milliseconds on the comparator input to make sure the threshold setting gets up to voltage before any noise can trigger the comparator.

 

I wish I knew how you can build diagrams like that from scratch. It's pretty impressive.

So, it looks like, so far, that this can be done with only a comparator and 555 (with various resistors and capacitors of course)?

 

LM311 Pinout follows.

 

Thanks. I think pin6 (strobe) grounded (3ma) = open collector. True?
We could use that for a latch out. I'm using the 555 reset to guarantee no start up glitches, but we could also ground it to force out = low.

Trigger (2) has to be at 2/3 Vcc before the reset pin goes high. Calculating timing sequence...
Not calculating. Trigger is already 470 times as fast as the reset. I'll assume it works.

 

Coming along. As it builds, I think the strobe is the right place to put the latch-out. What do you say, tracecom?
Can you find me an SCR with a hold current of less than 3ma?

 

I think so. Here's the configurations drawing.

 

I think this is about it, give or take some values.
I was asking if you personally know that grounding the strobe will force an open collector.
Oh...you think so. I guess we'll have to try this if we can get the right SCR.

 

I feel so helpless at this point...lol you guys are awesome!

 

TS110 SCR $.93
http://www.digikey.com/product-detail/en/TS110-7A1/497-13405-ND/3712265

There are some less expensive choices but the holding current is 5mA.

 

Excellent. I failed miserably at Mouser.

 

I think this is about it, give or take some values.
I was asking if you personally know that grounding the strobe will force an open collector.
Oh...you think so. I guess we'll have to try this if we can get the right SCR.

No, I don't know; will need to look at the datasheet.

Wow. Just noticed that this is my 2,000th post. Of course, that's nothing if you have over 5k.

 

I feel so helpless at this point...lol you guys are awesome!

How's the build coming?

It's time for this old man to turn in. CU!

 

Got a relay yet? 12V, <100ma, 3A or better, I think

 

Try this. If it doesn't work, post it as a question and lie about where you got it.