Close circuit timer with adjustable frequency

jon_k

I've been looking at 555 timers and other stuff but don't have the ability to control this stuff.

I want to trigger a circuit close with a relay, with accurate adjustments to a dial.

I want to be able to accurately control the trigger of the timer between 0.3 seconds to 1 minute.

So something with an LED would be nice, so I wouldn't have to use a stopwatch to check the calibration prior to deployment.

(This is for remotely triggering a camera shutter based on time passed.)

schip666!

The 555 is the old standby that you want. If you truly "don't have the ability to control this stuff" -- I presume you know nothing about electronics -- then you may not be able to continue with your project. But I would guess that you can make some more headway...

I googled "555 timer application notes" and came up with:
http://www.doctronics.co.uk/pdf_files/555an.pdf
that has a bunch of information about how to use it buried in the technical noise.

You might also find a kit that does what you want, like this one:
http://www.goldmine-elec-products.co...p?number=C6479

good luck

dlgoff

Using a stop watch probably isn't too accurate. Watching the pulses on an oscilloscope would give you better much results. Also the 555 is very dependent on the timing components i.e. the tolerances of the resistors and capacitors used to set the time.

That being said, I've used them in many applications and the best way, IMO, to learn it is to play with the application notes in the chips data sheet. So by all means check out this.

BTW the LM556 is a dual timer (two 555s in one chip)

berkeman

Welcome to the PF.

Another approach would be to see what kind of simple electronics kits are available for timers. I googled electronic kit timer, and got lots of good hits. At least this way you wouldn't have to be able to figure out how to design the timer circuit if you weren't ready for that yet, but you would still be able to see how the circuit was designed (most kits come with an explanation of how the circuit works), and you would be able to put the kit together yourself, to get some experience with simple assembly and soldering.

http://www.google.com/search?sourcei...onic+kit+timer

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