Date:         Sat, 5 Aug 2017 02:58:19 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Time Delay LED Lighting Circuit
Comments: To: Alistair Bell <albell@shaw.ca>
In-Reply-To:  <CAMOH8L+mVS5j_7nmG6YWfJd2TWnuOC4KTuggk5CruL-ne3FOkw@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"

Basic operation seems to be that the device is wired between permanent
ground and switched ground.  When the switched ground is released (door
closed) the big transistor is biased into conduction and carries the lamp
current.  I think this bias must initially come through the 5K6 resistor
and mumble mumble mumble keeping the second transistor biased on.  Over
time the cap charges through the 390K resistor and that magically via the
diodes operates on the second transistor to operate and shut down the first
one, which in turn shuts off the big guy.

Yrs,
d

On Sat, Aug 5, 2017 at 2:48 AM, David Beierl <dbeierl@attglobal.net> wrote:

> The 390K resistor has to be the timing resistor.  Both diodes and that
> resistor appear to be connected to the positive side of the cap.
>
>