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

[Synco Reynders]

So Volker, what did the MOSFET say to the raspberry pi?
" 'arm in charge 'n going break ya arm before making up" ??

Anyway I plan on coming.... Armed with more arm jokes.

On Tue, 4 Sep 2018, 22:03 Trevor Wignall <zl3adz at gmail.com> wrote:

> 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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