From: Ronald Teune <rtwolf_at_gmx.net>
Date: Wed, 14 Jul 2004 23:20:26 +0200

Hi Matthias,

On Wed, 14 Jul 2004 22:17:54 +0200, Matthias Klumpp
<Matthias.Klumpp_at_gmx.de> wrote:

> Hi Ronald,
>
> # What if we used standard 1N4148 diodes?
> # The voltage drop on the Schottky diode is 0.6 Volts.
> # If the uC out port is at 0 V, the AJB remote line will be pulled
> # down to 0.6 V;
>
> Isn't it less voltage drop in case of a Schottky ?
> As I understood Jörg, he wants the Schottky because of a lower voltage
> level
> than 0.6V when the uC port is 0V.

I meant to say I was doing in-brain circuit simulation with standard
1N4148, but perhaps wasn't very clear :-)

> # when the uC Out port is at 5 V, the AJB remote is at ~5 V due to
> # the pullup.
>
> That's still making me ?????????, because I still have that 5V level on
> the
> JB side.
> What if I make a resistor voltage devider, that makes the pull-up pull to
> 3.3V, like this:
>
> +5V
> |
> |
> +-+
> | |12k
> | |
> +-+
> |
> +-----------------+
> | |
> +-+ |
> | |22k |
> | | |
> +-+ |
> | |
> --- |
> |
> Schottky |
> uC Out port--------|<|---------+-- AJB remote
>
> # (it's easy to make mistakes though, with this kinda stuff,
> # especially since it's holiday - so correct me if i'm wrong)
>
> You are wrong - still NO holidays in Germany ;-)))
> Even so it's already a little bit late here and forthermore after a hard
> days work....
> maybe therefore ?

Hehe... again I probably was unclear... I meant that _I_ had holiday, so
_I_ could be wrong :-)
That voltage divider thingy is probably cool too.
Maybe the best and fastest way to correctly simulate is just take 5V, a
multimeter, a diode and two resistors :-)

> # Perhaps PSPICE has some problems with grounding and stuff; how
> # exactly did you connect a ground to this schematic?
>
> Well the schematic is only "the upper half" of the circuit.
> I've taken a pulse generator symbol to get a 20ms/5V rectangle signal as
> the
> uC out.
> On the AJB remote side I have a 1M resistor to ground (simulating a high
> impedance input).

hmm... sounds right... well, whatever :-P
I would like to build a remote too, I think it'll be quite useful. And the
one Steve Russel describes seems dirt cheap, so why not... the problem
would be a decent, small enough box to put the buttons and PIC in and not
to be too big. Is your design better? ;-)

> Greetings
>
> Matthias
>
> _______________________________________________
> http://cool.haxx.se/mailman/listinfo/rockbox
>

Greetings,

Ronald (aka zeekoe)
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Received on 2004-07-14