I need an adjustable timer for my PIR-activated light

[spiffitz]

Hello. I am wanting to do something similar to this:
**broken link removed**

Found a 6v DC battery-powered, AC optional PIR motion sensor light. The only settings are Off, Auto, and On. In Auto mode, the light stays on for 30 seconds. You can guess what the other two modes do.

What I need is a timer circuit that can be triggered by the output that powers the light. The timer would then trigger a relay to switch on a higher-powered DC circuit for a set amount of time. I want the timer to be adjustable from 1 to about 30 seconds max. The PIR's default timer would guarantee me at least a 30-second wait time before triggering again.

I am planning to wire the relay to screw terminals so I can use it for triggering different devices.

The reference provided by the link above no longer exists, although they do have **broken link removed**

Any leads to schematics on building something like this? I've Googled all day and the search here doesn't like "555". Thanks

 

[Tarsil]

Hello. I am wanting to do something similar to this:
**broken link removed**

Found a 6v DC battery-powered, AC optional PIR motion sensor light. The only settings are Off, Auto, and On. In Auto mode, the light stays on for 30 seconds. You can guess what the other two modes do.

What I need is a timer circuit that can be triggered by the output that powers the light. The timer would then trigger a relay to switch on a higher-powered DC circuit for a set amount of time. I want the timer to be adjustable from 1 to about 30 seconds max. The PIR's default timer would guarantee me at least a 30-second wait time before triggering again.

I am planning to wire the relay to screw terminals so I can use it for triggering different devices.

The reference provided by the link above no longer exists, although they do have this.

Any leads to schematics on building something like this? I've Googled all day and the search here doesn't like "555". Thanks

http://www.williamson-labs.com/555_tmg.htm
**broken link removed**
This helps?
Read on last link "Triggering And Timing Helpers For Monostable Timers" and on..
For more info google "555 timer".
The uC is also an option (u'l use like a 1$ uC and can implement later other functions).

 

[Hero999]

I've Googled all day and the search here doesn't like "555". Thanks

That's because 555 on its own is meaningless, NE555 is the full part number it's just people often abbreviate it.

https://www.google.com/search?client=opera&rls=en&q=Ne555&sourceid=opera&ie=utf-8&oe=utf-8

 

[spiffitz]

Since I know next to nothing about these things, I was asking if anyone knew how the above kit was made. The search doesn't work here because "555" is below the minimum required number of characters. Searching for the exact part number excludes a lot of things, since people do type "555" to make things simple.

Anyway I found this page, which should do what I want. It won't be adjustable, but I can live with a 2 second pulse for now and I will modify it as I need to (and learn more about it) later on.

 

[riverman]

Anyway I found this page, which should do what I want. It won't be adjustable, but I can live with a 2 second pulse for now and I will modify it as I need to (and learn more about it) later on.

If you build the first circuit on that page (the non-oscillating one) but replace the 10k ohm resistor RA with a 10k ohm variable resistor, you should be able to adjust the time between about 0 & 2 secs. Using a larger capacitor or a higher value variable resistor will both give you a longer time delay.

 

[spiffitz]

If you build the first circuit on that page (the non-oscillating one) but replace the 10k ohm resistor RA with a 10k ohm variable resistor, you should be able to adjust the time between about 0 & 2 secs. Using a larger capacitor or a higher value variable resistor will both give you a longer time delay.

Thanks for that piece of advice, it's exactly what I'm looking for.

According to their formula:

t1 = charge time (how long the LED is on) = 0.693 * (RA + RB) * C

since RB is non-existant, I get ~1.5 seconds. Substituting RA with a 100k potentiometer will then get me up to 15 seconds. Am I understanding this correctly? Too bad RS doesn't list a 15-turn 100k (rather buy locally) but I can do with a large dial.

To make an arming circuit that would allow me to walk away from the unit without triggering it, I could build two of these. The first one timed to arm the second circuit, second circuit to activate the relay. Or is there an easier way?

This is getting more fun as I learn. Thanks for all the tips.

 

[spiffitz]

Well I finally got all the pieces and ready to go. I figured out that my old camcorder will start recording once turned on if the record button is held down. I took it apart and found that the buttons are wired through a ribbon cable.

Is it feasible to solder onto a ribbon cable? It's flat (obviously) and covered with a brown film. Should I take the camera apart further and hope there are PCB contacts I could solder onto instead?

I tried scraping some film off, but the solder wouldn't stick. Then I tried tinning the wire and applying the iron to the wire pressed against the ribbon. It stuck but as soon as any pressure was applied it came right off.

 

[Nigel Goodwin]

Solder to a PCB, you can't do anything with those film ribbons!.

 

[Hero999]

The search doesn't work here because "555" is below the minimum required number of characters. Searching for the exact part number excludes a lot of things, since people do type "555" to make things simple.

Use a propper search engine like Google.

Guess what a Google search for 555 brings up? Look at the first result! There's no excuse!
https://www.google.com/search?client=opera&rls=en&q=555&sourceid=opera&ie=utf-8&oe=utf-8

 

[spiffitz]

Use a propper search engine like Google.

Guess what a Google search for 555 brings up? Look at the first result! There's no excuse!
https://www.google.com/search?client=opera&rls=en&q=555&sourceid=opera&ie=utf-8&oe=utf-8

Thanks but that's already been figured out. Read the entire thread instead of just responding to the first post from almost a month ago, where I specified the search here, not Google, doesn't work for "555". There's no excuse!

Solder to a PCB, you can't do anything with those film ribbons!

I read on another forum that someone used sandpaper to rub off the film and it worked, but perhaps his ribbon was thicker. Today at work I was using **broken link removed** to lay down SMDs and was wondering if the ribbon could take the hot air, but with solder paste. Frequently I work from home, so perhaps I'll take that puppy with me and experiment on a junk ribbon cable from a CDROM drive or something. But I guess it would be more fun to take it apart further to find a PCB point.

 

[Hero999]

I specified the search here, not Google, doesn't work for "555". There's no excuse!

You can still use Google to search this site you know!
https://www.google.com/search?as_q=...ectro-tech-online.com/&as_rights=&safe=images

 

[1Steveo]

See if you can find a resistor connected to the switch in auto mode. You might be able to replace it with a "POT" to make it adjustable!

Can you get a good picture of the board front and back?

 

[spiffitz]

See if you can find a resistor connected to the switch in auto mode. You might be able to replace it with a "POT" to make it adjustable!

Can you get a good picture of the board front and back?

I tried giving it a good look-over but there are more resistors than I know what to do with. It's attached to teh camera now, but I will take it apart again to get pictures of the board.

BTW this device was to activate a relay to switch on a video camera. I did catch the critters on tape, they were opossums! I re-configured the obstacle so they could theoretically escape the attic but not get back in, however the bulb on the light burned out and all I got was dark footage. Lots of action, too, since the tape was going for a while. Darn it..