simple one-shot pulse detector circuit needed

a reed switch like used for alarms...

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?? 100% natural 

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

detector out of two of transistors and a few resistors, but I can't find the circuit anywhere. Searches keep throwing up stuff about astable multivibrators and nand gates and that's not what I'm looking for.

The pulse comes only after several days of inactivity and should turn an LED on permanently. No reset required and any subsequent pulses must *not* turn the LED off again, so it's operating like a bistable latch (if that's the right term).

just make an SCR out of your two transistors.

one resistor on the gate input and a series resistor to limit the LED current.

--
?? 100% natural 

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Perhaps it would be more productive to fix or improve the gate closing mechanism, thus eliminating the need for a weather proof switch and associated electronics? There is a wide variety of gate closing mechanisms available, usually based on a linear or rotary spring mechanism. Many can be retrofitted to an existing gate:

Then, there's the cannonball gate closer:

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Actually I want to know that it was opened. Got a Mexican claiming he worked when he didn't :-( ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     | 
| Analog Innovations, Inc.                         |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

detector out of two of transistors and a few resistors, but I can't find the circuit anywhere. Searches keep throwing up stuff about astable multivibrators and nand gates and that's not what I'm looking for.

line. The pulse comes only after several days of inactivity and should turn an LED on permanently. No reset required and any subsequent pulses must *not* turn the LED off again, so it's operating like a bistable latch (if that's the right term).

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What are you talking about?

detector out of two of transistors and a few resistors, but I can't find the circuit anywhere. Searches keep throwing up stuff about astable multivibrators and nand gates and that's not what I'm looking for.

line. The pulse comes only after several days of inactivity and should turn an LED on permanently. No reset required and any subsequent pulses must *not* turn the LED off again, so it's operating like a bistable latch (if that's the right term).

Once tripped, have it blink to save power. (I'm thinking battery power.) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     | 
| Analog Innovations, Inc.                         |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Oh...

Writing software, designing gate alarms, and in general, solving problems are all easy if you don't worry about error conditions. Real problem solving is more about dealing with oversights, errors, anomalies, stupidity, and abuse, than about making it work. Whenever approaching such things, I ask "What problem are you trying to solve?" The answer often eliminates a wide assortment of obvious and usually impulsive solutions.

If you can see the gate from the house, install a security camera and DVR. I recommend the clear picture of an IP camera over the fuzzy blurr of a composite video camera. Then you can see who or what opened the gate. If the Mexican worker is clever, he'll probably "accidentally" jam the gate open and defeat your scheme. If a camera and DVR are too elaporate, a PIR motion sensor will detect the Mexican directly.

However, if you must have a gate switch, the previously recommened proximity sensors are probably good enough. A burglar alarm type reed switch and magnet will also work if you keep them away from the metal gate.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

se detector out of two of transistors and a few resistors, but I can't find the circuit anywhere. Searches keep throwing up stuff about astable multiv ibrators and nand gates and that's not what I'm looking for.

0v line. The pulse comes only after several days of inactivity and should turn an LED on permanently. No reset required and any subsequent pulses mus t *not* turn the LED off again, so it's operating like a bistable latch (if that's the right term).      ...Jim Thompson     ...Jim Thompson

I gathered that, Jim. Good suggestion on your part; I just can't get that link to bring up any results for some reason. :(

I must be having a really bad day, George. Ain't got no such folder on my system!

On Wed, 21 Nov 2012 12:28:12 -0800 (PST), phaedrus wrote:

--- Here's the circuit list again, just in case...

Version 4 SHEET 1 880 680 WIRE 16 -192 -496 -192 WIRE 160 -192 16 -192 WIRE 16 -144 16 -192 WIRE 160 -144 160 -192 WIRE 16 0 16 -64 WIRE 160 48 160 -64 WIRE 160 48 80 48 WIRE 160 80 160 48 WIRE 160 176 160 144 WIRE -352 224 -400 224 WIRE -208 224 -272 224 WIRE -128 224 -208 224 WIRE 16 224 16 96 WIRE 16 224 -64 224 WIRE 96 224 16 224 WIRE -496 256 -496 -192 WIRE -400 256 -400 224 WIRE -208 272 -208 224 WIRE 160 320 160 272 WIRE -496 432 -496 336 WIRE -400 432 -400 336 WIRE -400 432 -496 432 WIRE -208 432 -208 336 WIRE -208 432 -400 432 WIRE 160 432 160 400 WIRE 160 432 -208 432 WIRE -496 496 -496 432 FLAG -496 496 0 SYMBOL res 144 -160 R0 SYMATTR InstName R1 SYMATTR Value 330 SYMATTR SpiceLine "" SYMBOL npn 96 176 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL pnp 80 96 R180 SYMATTR InstName Q2 SYMATTR Value 2N3906 SYMBOL diode -128 240 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D1 SYMATTR Value 1N4148 SYMBOL res -256 208 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 68k SYMATTR SpiceLine "" SYMBOL cap -224 272 R0 SYMATTR InstName C1 SYMATTR Value 47µ SYMATTR SpiceLine "" SYMBOL LED 144 80 R0 SYMATTR InstName D2 SYMATTR Value NSCW100 SYMATTR Description Diode SYMATTR Type diode SYMBOL voltage -400 240 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value PULSE(0 5 1 1u 1u 1 0 1) SYMATTR Value2 "" SYMATTR SpiceLine "" SYMATTR InstName V1 SYMBOL voltage -496 240 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value2 "" SYMATTR SpiceLine "" SYMATTR InstName V2 SYMATTR Value 10 SYMBOL res 0 -160 R0 SYMATTR InstName R4 SYMATTR Value 1000 SYMATTR SpiceLine "" SYMBOL res 144 304 R0 SYMATTR InstName R3 SYMATTR Value 39 SYMATTR SpiceLine "" TEXT -488 456 Left 2 !.tran 3

Now, here's what to do:

1. On your newsreader's screen, copy the entire list, including "Version 4", to the clipboard by selecting all the text, then pressing CTRL-C.

1. Launch Word Pad or any other plain ASCII text editor, and paste the circuit list into it by pressing Ctrl-V.

2. Using "Save As", assign a filename to the list (say, "1s pulse detect.asc") and save it to any folder you like. Make _sure_ the file has a .asc filename extension.

1. Now, navigate over to the folder to where you saved "1s pulse detect.asc", and left click on the file.

If .asc files are associated with LTspice in your box, then LTspice will find it and you'll see the schematic pop up.

If that doesn't happen, launch LTspice, navigate to the file, and left-click on it.

The schematic should appear, and then you can play with the circuit 'til your heart's content.

1. Enjoy! :-)

-- JF

You keep adding requirements to the spec. Often, it's useful to monitor the thing you want monitored. Monitoring attendance is no guarantee that you actually get work. Stated another way: If you can't tell if the work was done, you're paying for work you don't need.

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news:29esa8pmakmtpl7tq0ra5srgpa8htnloag@4ax.com

e t

Finally! Thank you, John. Don't know what the problem is this end, but your list combine with my version of LTS generated a corrupted schematic with several components rotated and out of position! Anyway, I was able to reconstruct the corrupted diagram and it now works fine. Thanks again!

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My pleasure. :-) 

You might want to "synchronize" with LTC by going to: 

http://www.linear.com/designtools/software/ 

and downloading the latest version of LTspice IV.

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Actually, I think the right way to do it is to click on "Tools", "Sync 
Release", "OK", and then it'll do it all automagically.

Many thanks.

Given your other writings and the generally pejorative outlook towards your fellow man, why am I surprised to read "mexican?"

Larry

Because that's who he paid to do the work? Who else was he going to hire in Arizona to work outside in the heat?

Yep. The white guy I fired for poor workmanship also didn't seem to want the work.

Don't fret over Lawrance... he can't even spell his own name correctly ;-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     | 
| Analog Innovations, Inc.                         |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.