> What do you think of diode plus resistor from transistor collector to Vdd
> or some other higher supply rail, providing that the rail is "stiff" at t=
he
> energy level and transfer rates concerned?
>
>
The voltage across the resistor would be dependent on how many relays got
released and how fast, which makes it harder to predict.  Assuming open
collector/drain drivers:  If each relay has a diode that connects them to a
common zener to ground, then the voltage across any collector is the zener
voltage plus diode drop, small inductive effects and diode turn on time
will add some.  That seems more predictable to me, and if the zener voltage
is set high enough it means that the relays are releasing quickly.

The ULN2000 series with its collectors having common diodes to a single pin
seems designed to that intent.

This is one of those points, like using load caps of n pf on an n pf
crystal, where the common practice is not the right practice.
--=20
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