[minima] Re: Linear Output Filter Switching

  • From: Dan Reynolds <on30ng@xxxxxxxxx>
  • To: minima@xxxxxxxxxxxxx
  • Date: Fri, 31 Jan 2014 19:31:56 -0600

I'm not any kind of an expert but could you use a Microchip MCP23017 I/O
expander on the 5 V side of the I2C bus. I was thinking something like I
saw on the Tronixstuff page here:
http://tronixstuff.com/2011/08/26/tutorial-maximising-your-arduinos-io-ports/
Instead of a LED an I/O line could drive a transistor to drive a relay(?).
Then the code could "watch" the frequency and as it changes the output line
for that particular LPF could be switched.

Or could you use a 74HC595 to accomplish the same thing.
http://tronixstuff.com/2010/04/30/getting-started-with-arduino-chapter-four/

I was going to approximate the Minima front panel with a bare bones Arduino
and some parts and see what I could dream up.
I don't really know what I'm doing. I'm just muddling through trying to
patch bits and pieces together...


73
Dan -- KB9JLO
https://sites.google.com/site/on30ng/


On Fri, Jan 31, 2014 at 6:10 PM, Wayne McFee <nb6m@xxxxxxx> wrote:

> Hi Mark,
>
> If the three outputs were set up as you suggest, a Picaxe chip could be
> programmed to control either individual relay driver transistors or a relay
> driver chip like the 2903(?).
>
> I've been using that arrangement for filter selection  in a homebrew rig.
>
> Or, if one of those output lines could be programmed to output a stepped
> voltage such as that provided by the FT817 for bandswitching info, that
> makes the programming even easier.
>
> Wayne NB6M
>
>
> > On Jan 31, 2014, at 1:24 PM, Mark G0MGX <mark.g0mgx@xxxxxxxxx> wrote:
> >
> > Farhan & Team,
> >
> > I can see that we have provision in the schematic for 3 digital outputs
> for band selection, but can only see one of these (BAND_HI - pin 11 -
> Arduino D5) being used within the function "setBandswitch". It is this
> function that currently selects the LPF used based on frequency.
> >
> > We could set the state of the three outputs based on frequency something
> like this:
> >
> > <Filter Ideas.png>
> >
> > But someone far cleverer than I would need to explain how to create
> relay on/off switching based on the logic states of  the three lines - I
> have no idea how to do that!
> >
> > If we were to implement something like this was the intention to use
> these additionally switched filters in RX as well as TX?
> >
> > I would be interested in your thoughts and ideas on how you saw this
> working before I head down the wrong road with my construction!
> >
> > Many thanks,
> >
> > Mark
> > G0MGX
>
>

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