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

Hi Ronald,

# -----Ursprüngliche Nachricht-----
# This schematic is exactly the same (IIRC) as used in old Diode
# Logic (but now only 1-input nand) so it should work...

I confirm, when I think about it.
Therefore I already mentioned (between the lines ;-)) that maybe that
simulation
is not as good as it should be.

# 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.

# 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 ?

# 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).

Greetings

Matthias

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Received on 2004-07-14