Archived posting to the Leica Users Group, 1998/10/26

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Subject: Re: [Leica] M6TTL and M7 Clues
From: dmorton@journalist.co.uk (David Morton)
Date: Mon, 26 Oct 1998 9:45 +0000 (GMT)

Jim wrote:

> This explains why the LED's switch on/off and required a third LED
to
> show
> proper exposure. There is no such thing as a dim-able LED with
digital
> circuitry. It's either on or off. No in between. Maybe I could
learn to
> like the TTL after all.

Actually you can. You switch it on an off too quickly for the eye to
see (say 100Hz or so) and vary the mark-space ratio. Actually that's
usually how you do it even with analogue driving circuits.

David Morton
dmorton@journalist.co.uk
David.Morton@openconsulting.co.uk
(+44) 171 917 6272