[chbot] Next Robotics meeting, 17th Sept 2018 : ARM special

[Trevor Wignall]

I certainly aim to be at the meeting.
A few resistors would have given immunity to that make before break
problem, and solved the threshold problem too. In fact, you don't even need
to switch to +5 Volts if you have a resistor between MOSFET gate and source
(+5V).
Trevor


On Tue, Sep 4, 2018 at 5:33 PM Volker Kuhlmann <list57 at top.geek.nz> wrote:

> On Mon 03 Sep 2018 13:08:36 NZST +1200, Stephen Irons wrote:
>
> > Make before break on the slide switch, connecting either power or
> > ground to the I/O pin that was driving the other way?
>
> The key words here are "make before break". With a MOSFET I thought I
> should get away with a very simple circuit, connected the switch centre
> to the MOSFET gate, and the 3 switch positions to 5V, I/O pin, GND.
> Because I don't have output pin control working yet I connected the
> switch terminal meant for the I/O pin to 3.3V to see if (5 - 3.3)V
> exceeds the gate threshold voltage (it does). Operating the switch then
> temporarily shorted 5V with 3.3V on the RPi pin header... and the new 5V
> 2.5A RPi plug packs give enough uumph to cause some real problem!
>
> Volker
>
> --
> Volker Kuhlmann
> http://volker.top.geek.nz/      Please do not CC list postings to me.
>
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