Hello,
can anyone please point me to a circuit that I can use to stretch the on time of an LED when the on pulse is small? I have a push botton that I want to press momentarily and see a longer (say 1 second) illumination of the LED.
Many thanks in advance.
Gaz
Look at monostable configuration in the applications section of a 555 data sheet. Trigger pulse produces one output pulse - applying that to your switch and LED should be obvious.
Or use a Sherman tank where a BB gun would do, and use a microprocessor. In cases where you have a lot of complexity already, and/or have a micro in there already, it makes sense. If this is all you want to accomplish, it's a bit overkill.
-- Cats, coffee, chocolate...vices to live by
This concept is synonymous with "pulse stretcher":
A 555 can source 200mA:
Look at page 5 of this link:
A monostable multivibrator is basically a pulse stretcher with a fancy name. Look at the other application circuits. Lots of fun stuff you can do with a
555.Regards, Bob Monsen
Thinking about this again, you might not have "a LED". There are some gizmos that they put on e.g. candy displays.
These are a plastic housing containing a stack of 3 button cells and a device that looks like a LED. What that is is a clear package that houses a LED
*PLUS* an on-board chip that flashes the LED. If you look at it closely with a strong magnifier, you can see the chip.There is nothing you can do to change the flash rate of this thing.
On Fri, 15 Feb 2008 18:38:33 GMT in sci.electronics.basics, Ecnerwal wrote,
Isn't that overkill? He's talking about keeping a LED on long enough to see it, not a Precision Timer job. Wouldn't a real designer be able to do that with, say, a capacitor and a single transistor?
You've got to be joking.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.