[sdiy] some disturbing things i've read recently

[patchell]

Gavin Russom wrote:

> well I'm moving along on my modular but I've recently run across a couple of
> technical "facts" that have alarmed me because i'd never heard anything
> about any of them and am not prepared
> 1. An IC will not work properly or at all if the power leads are too long, a
> possible solution for this is to put a .1 uF capacitor across the power
> leads (I imagine this is a filtering cap to suck off any transients that
> would be coming through the power lead?) Any body ever run into this
> phenomenon?

    This is very highly dependent on what the IC is and how it is used.  To me,
it doesn't matter.  As far as I am concerned, you can never have too many power
supply bypass capacitors.  For analog stuff, your biggest problem are moderate
to high frequency opamps.  Something like a uA741 probably doesn't care if the
supplies are bypassed, but a TL071 will care under certain conditions (I always
bypass BiFet opamps).  Something like the LM13600/700, probably for the most
part, doesn't care, but, again, it depends on how it is used.  Be safe, bypass.

    Also, I prefer to bypass the power supply leads to ground, rather than
bypass across them..

>
> 2. What is a system DAC? I've looked through all my books and can't find
> anything about it.
> thanks
> MYSTIC

    A DAC is a Digital Analog Converter.  "System DAC", probably depends on how
that is used as to what it means.  Many synths had only one DAC in them that was
multiplexed to a bank of sample and holds (DACs are generally pretty pricey).

--
 -Jim
------------------------------------------------
* Visit:http://www.silcom.com/~patchell/
*-----------------------------------------------
*I'm sure glad Merry Christmas comes just once a year
* -Yogi Yorgensen
------------------------------------------------