Re: [CAD_CAM_EDM_DRO] Opto Isolator Switching

On Tue, 3 Dec 2002, Peter Cruickshank wrote:

> I have isolated my limit switches using a TLP540 Opto Isolator,
> however it appears unable to drive TTL logic directly and it cannot
> switch the input of a 7408 NAND Gate without using a 2N2222
> Transistor in between.
>
> Does anyone know if I can drive a ULN2003 Darlington directly from
> the isolator without having to use the 2222 as an amplifier ??

Without having datasheets I would just try it and see. Since it's a
darlington the input current should be pretty low so I would think
it should work.

> I am also experiencing some switch bounce and wondered if it would
> be preferable to setup an R/C network to turn the signal into a
> pulse or to dampen the switching ??

Dampen it how, mechanically? Not sure how you would do that since the
bouncing is from the switch contacts themselves which are inside the
switch. The R/C thing is a standard way to debounce switches and should
work fine.

And this is kinda off-topic...

C|