Date:         Sun, 6 Aug 2017 19:03:58 -0700
Reply-To:     Alistair Bell <albell@SHAW.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Alistair Bell <albell@SHAW.CA>
Subject:      Re: Time Delay LED Lighting Circuit
Comments: To: David Beierl <dbeierl@attglobal.net>
Comments: cc: Dick Wong <sailingfc@dslextreme.com>
In-Reply-To:  <CAMOH8LKv4pkGrWTZpkSU0zrN637r=6eA6iMh76fwe=Mt7PHk_w@mail.gmail.com>
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Ok, I'm not going to pretend to know... is it just the cap that determines delay time? 

Ab

> On Aug 6, 2017, at 6:23 PM, David Beierl <dbeierl@attglobal.net> wrote:
> 
> And here's the schematic: https://goo.gl/photos/mcHajDYPoanHXZbe8
> 
> Yrs,
> d
> 
>> On Sun, Aug 6, 2017 at 8:48 PM, David Beierl <dbeierl@attglobal.net> wrote:
>> Hokay, here's how it works.  Components are numbered left to right and top to bottom in Dick's photo of the component side of the board.  Red wire (+) goes to switched ground, black wire (-) to unswitched ground.
>> 
>> When door is closed, + lead is pulled up toward V+ through the lamp.  Q2 base is pulled up through R1 5K6.  It is biased into conduction and its emitter pulls up the base of Q1, the big guy, biasing it into conduction and limiting the voltage across it to call it a volt, thus lighting the lamp.
>> 
>> At the same time, C1 begins to charge through R2 390K.  Its + side is connected to Q3 base through D1, so once the cap voltage reaches 0.6 or so it pulls up Q3 base and Q3 begins to conduct.
>> 
>> Q3 emitter is grounded and collector is connected to the + bus through R1, the same resistor that's biasing Q2 base positive.  When it conducts it pulls Q2 base down, shutting off Q2 which in turn shuts off Q1 and stops the music.  C1 continues to charge and eventually reaches V+.
>> 
>> When the door is opened, C1 immediately drains down to about 0.6V through D2, resetting the circuit for the next delay.
>> 
>> Yrs,
>> d
>> 
>> 
>> 
>>> On Sun, Aug 6, 2017 at 3:36 PM, Alistair Bell <albell@shaw.ca> wrote:
>>> Hi Dick,
>>> 
>>> Your delay module is pretty well perfect. If you can't get it working again there is my banggood substitute. I've made a video showing it mocked up, set for 12 second delay on the relay.
>>> 
>