On Fri, 1 Nov 2002, Olin Lathrop wrote:

*>The gain is low and there is no hysteresis.  When the light level changes
*>slowly the relay will be slowly driven thru the on/off range.  One

Imho it is very hard to drive a relay slowly through its on-off range
because most relays have a linear spring and a quadratic magnetic force
component. This causes built-in hysteresis on both make and break.

Otoh in Ake's circuit any ac (including from arcing contacts) can make it
to the base and contribute to a positive feedback loop.

Peter

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