[minima] Re: Linear Output Filter Switching
- From: Wayne McFee <nb6m@xxxxxxx>
- To: "minima@xxxxxxxxxxxxx" <minima@xxxxxxxxxxxxx>
- Date: Thu, 6 Feb 2014 09:11:04 -0800
That way you will have enough current and switching capability to go up to a
little higher power, 50W at least, should you care to, and it provides a little
extra capability for lower power, which won't hurt a thing.
73,
Wayne NB6M
> On Feb 6, 2014, at 9:01 AM, Wayne McFee <nb6m@xxxxxxx> wrote:
>
> Hi Mark,
>
> I would suggest using the Omron 2Amp DPDT relays to switch the filters and
> parallel the two poles.
>
> Wayne NB6M
>
>
>> On Feb 6, 2014, at 3:52 AM, Mark G0MGX <mark.g0mgx@xxxxxxxxx> wrote:
>>
>> Hi Team
>>
>> I've done a bit more work on the output filter switching using a 4028 (which
>> arrived today!).
>>
>> The wiki is updated:
>>
>> http://www.hfsignals.org/index.php/Final_Output_Filters
>>
>> Including a link to a simple sketch to try and illustrate how it works and
>> enable others to prototype the ideas as I have.
>>
>> There will be more on this topic from me....
>>
>> Mark
>> G0MGX
>>
>>
>>> On 04/02/2014 19:05, Dan Reynolds wrote:
>>> Thanks Mark. I'm learning a lot but you know how it is when you're dreaming
>>> - you never learn fast enough. I'm pouring over tutorials on the
>>> web to help me understand better.
>>>
>>> I think I know what the schematic will look like but I just want to see it
>>> from a more credible source than my brain!
>>>
>>> I hope to have the Boarduino and the front panel all mocked up by the
>>> weekend. I have an Si570 on the way. I'm going to use the WB6DHW Si570
>>> board for the level shifter circuit.
>>> http://wb6dhw.com/For_Sale.html#Si570
>>> That should also keep me out of trouble with modifying that one library...
>>>
>>> Then I can start mocking up / playing with the LPF selection logic
>>> perhaps...
>>>
>>> Thanks everybody. This is a neat project and I'm going to learn a whole lot!
>>>
>>>
>>> 73
>>> Dan -- KB9JLO
>>> https://sites.google.com/site/on30ng/
>>>
>>>
>>>> On Tue, Feb 4, 2014 at 12:53 AM, Mark G0MGX <mark.g0mgx@xxxxxxxxx> wrote:
>>>> Hi Dan & Team
>>>>
>>>> When I get the CMOS chips I have ordered I will publish to the Wiki the
>>>> schematic for filter switching, details for interfacing to the bare bones
>>>> Arduino and also publish my suggested code modifications/changes to
>>>> control the switching based on radio frequency. I will also put extensive
>>>> comments into the code to explain what's going on.
>>>>
>>>> The ULN2803a does look like a great option - I have just ordered some of
>>>> those from eBay - so I will experiment with this option also in due course.
>>>>
>>>> Mark
>>>> G0MGX
>>>>
>>>>
>>>>
>>>>> On 03/02/2014 22:18, Dan Reynolds wrote:
>>>>> I wish someone could draw up a schematic and show a modified codes
>>>>> segment so someone dense like me can get his head around it.
>>>>>
>>>>> I looked at that CD4028 example and Mark, your second chart is starting
>>>>> to make sense...
>>>>> I think the ULN2803a is a good idea too.
>>>>> Do you ground the unused inputs on that chip?
>>>>> And then I assume the common on the output side would go to +12V for
>>>>> relay energizing power.
>>>>>
>>>>> This project could be an excellent learning project for me all the way
>>>>> around! :-)
>>>>>
>>>>> 73
>>>>> Dan -- KB9JLO
>>>>> https://sites.google.com/site/on30ng/
>>>>>
>>>>>
>>>>> On Sun, Feb 2, 2014 at 12:51 PM, Wayne McFee <nb6m@xxxxxxx> wrote:
>>>>>> Mark,
>>>>>>
>>>>>> I'm using a ULN2803a Darlington Driver chip to drive the relays for LPF
>>>>>> selection in a homebrew amp. These have the back current diodes in
>>>>>> them, so no external diodes needed across the relays.
>>>>>>
>>>>>> Just a thought, as it saves building individual drivers with transistors
>>>>>> (like I did in another project).
>>>>>>
>>>>>> Wayne NB6M
>>>>>>
>>>>>> On Feb 2, 2014, at 6:54 AM, Mark G0MGX <mark.g0mgx@xxxxxxxxx> wrote:
>>>>>>
>>>>>>> Hi Gang
>>>>>>>
>>>>>>> I've completed a proof of concept of the output filters today; it uses
>>>>>>> a 74141 as a BCD to individual selection connected to a 74LS00 used as
>>>>>>> NOT gates or inverters for the output lines.
>>>>>>>
>>>>>>> I can control this OK from the Arduino code, so I have ordered some of
>>>>>>> these CMOS 4028s as this has a HIGH output state when an output is
>>>>>>> selected whereas the 74141 is a LOW state when an output is selected (I
>>>>>>> have used 74141 previously to ground cathodes of Nixie tubes!). This is
>>>>>>> the logic of the chip:
>>>>>>>
>>>>>>> <74141 logic.png>
>>>>>>>
>>>>>>>
>>>>>>> So I now wait for the postman before I can complete the filter output
>>>>>>> stage.
>>>>>>>
>>>>>>> I am thinking that we might like options in the code/filters as it
>>>>>>> seems to me we need to keep the current RX filter selection pin usage,
>>>>>>> but also use this for filter selection. We can go with very simple as
>>>>>>> suggested by Farhan and have 4 filters, or we can have 5 to include
>>>>>>> either top band or 60M (5MHz).
>>>>>>>
>>>>>>> I will post more when I have the final design and code mods once built
>>>>>>> and tested. I am definitely going with a 3 line BCD output from the
>>>>>>> Arduino processor to select filters based on radio tuned frequency.
>>>>>>> This will be accomplished in the existing function "setBandswitch".
>>>>>>> Maybe (only maybe) something like this:
>>>>>>>
>>>>>>> <Filter Ideas3.png>
>>>>>>>
>>>>>>>
>>>>>>> In the code we will declare three digital outputs (including the
>>>>>>> existing BAND_HI) and set all three each time we change frequency, the
>>>>>>> state (HIGH or LOW) of each output will be dependent on frequency and
>>>>>>> in accordance with the truth table and output usage above.
>>>>>>>
>>>>>>> Mark
>>>>>>> G0MGX
>>>>>>>
>>>>>>>> On 01/02/2014 18:47, Mark G0MGX wrote:
>>>>>>>> very good. That CMOS chip used in the link looks the same as the TTL
>>>>>>>> 74141 - but I am no expert.
>>>>>>>>
>>>>>>>> This does seem to be the way to go
>>>>>>>> Mark
>>>>>>>> G0MGX
>>>>>>>>
>>>>>>>>> On 01/02/2014 18:24, mpcharlton@xxxxxxxxxxx wrote:
>>>>>>>>>
>>>>>>>>> Mark
>>>>>>>>>
>>>>>>>>> Have a look at this halfway down the page...
>>>>>>>>>
>>>>>>>>> http://www.vk5tm.com////homebrew/filter/filter.php
>>>>>>>>>
>>>>>>>>> Mark
>>>>>>>>> G6ZQS G-QRP 2247
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> -------Original Message-------
>>>>>>>>>
>>>>>>>>> From: Mark G0MGX
>>>>>>>>> Date: 01/02/2014 17:29:09
>>>>>>>>> To: minima@xxxxxxxxxxxxx
>>>>>>>>> Subject: [minima] Re: Linear Output Filter Switching
>>>>>>>>>
>>>>>>>>> Isn't this:
>>>>>>>>>
>>>>>>>>> http://www.g3ynh.info/digrdout/74141.html
>>>>>>>>>
>>>>>>>>> exactly what we need to go from Binary outputs on our 3 digital lines
>>>>>>>>> to
>>>>>>>>> individual relays controlling filters?
>>>>>>>>>
>>>>>>>>> Mark
>>>>>>>>> G0MGX
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 01/02/2014 15:26, farhanbox@xxxxxxxxx wrote:
>>>>>>>>> > Mark,
>>>>>>>>> > There's something not
>>>>>>>>> > right about the curve. The stopband is quite nominal. You
>>>>>>>>> > must get atleast 60 db stop-band.
>>>>>>>>> >
>>>>>>>>> > Sent from BlackBerry® on Airtel
>>>>>>>>> >
>>>>>>>>> > -----Original Message-----
>>>>>>>>> > From: Mark G0MGX <mark.g0mgx@xxxxxxxxx>
>>>>>>>>> > Sender: minima-bounce@xxxxxxxxxxxxx
>>>>>>>>> > Date: Sat, 01 Feb 2014 13:47:38
>>>>>>>>> > To: minima@xxxxxxxxxxxxx<minima@xxxxxxxxxxxxx>
>>>>>>>>> > Reply-To: minima@xxxxxxxxxxxxx
>>>>>>>>> > Subject: [minima] Re: Linear Output Filter Switching
>>>>>>>>> >
>>>>>>>>> > Hi Team
>>>>>>>>> >
>>>>>>>>> > I've started the output
>>>>>>>>> > filter Wiki page here:
>>>>>>>>> >
>>>>>>>>> > http://www.hfsignals.org/index.php/Final_Output_Filters
>>>>>>>>> >
>>>>>>>>> > and have so far put info on 4, 11 and 19MHz
>>>>>>>>> > cut off Low Pass Filters. I
>>>>>>>>> > am very unhappy with the 19M filter sweep, so will let you guys
>>>>>>>>> > take a
>>>>>>>>> > look before doing any more. The next filter needs to be 30M cut off
>>>>>>>>> > - we
>>>>>>>>> > already have one of those!
>>>>>>>>> >
>>>>>>>>> > As an aside I have dug out my CD from EMRFD and mine is a 2002
>>>>>>>>> > version
>>>>>>>>> > of the software which I
>>>>>>>>> > can't find a filter designer? I can enter values
>>>>>>>>> > myself but cant get the software to come up with the filter for me -
>>>>>>>>> > hence I have stuck with what I know and used QUCS for my designs.
>>>>>>>>> >
>>>>>>>>> > I do think that we could still use the existing D5 line for output
>>>>>>>>> > _*as
>>>>>>>>> > well as*_ the existing input filter switching just so long as the
>>>>>>>>> > line
>>>>>>>>> > stays HIGH for > 15MHz and LOW for <= 15MHz. This would give us
>>>>>>>>> > room for
>>>>>>>>> > a 1.8M filter and another if we find we need i. I have only
>>>>>>>>> > focused on
>>>>>>>>> > those highlighted yellow below, but clearly
>>>>>>>>> > with the three digital lines
>>>>>>>>> > we could have up to 8
>>>>>>>>> > filters if we needed them.
>>>>>>>>> >
>>>>>>>>> >
>>>>>>>>> >
>>>>>>>>> > I personally like the idea of simple logic chip or BCD type logic to
>>>>>>>>> > control relays as I feel that we want to avoid more programming and
>>>>>>>>> > complexity where it's not needed. The 74LS139 idea is a great one
>>>>>>>>> > and
>>>>>>>>> > probably the way I plan to go, but lets see what we decide.
>>>>>>>>> >
>>>>>>>>> > I've tried to explain some of this in the Wiki - please take a look
>>>>>>>>> > and
>>>>>>>>> > lets decide between us how we are going to do this part of the
>>>>>>>>> > project.
>>>>>>>>> >
>>>>>>>>> > We could of course go with the idea of a separate amplifier
>>>>>>>>> > completely,
>>>>>>>>> > maybe with the tubes others are suggesting! I've never built
>>>>>>>>> > anything
>>>>>>>>> > with tubes....
>>>>>>>>> >
>>>>>>>>> > Mark
>>>>>>>>> > G0MGX
>>>>>>>>> >
>>>>>>>>> > On 01/02/2014 06:48, Mark wrote:
>>>>>>>>> >> Thanks to everyone for the suggestions and ideas.
>>>>>>>>> >>
>>>>>>>>> >> If we go with 4 filters have we scrapped top band?
>>>>>>>>> >>
>>>>>>>>> >> I'll try and run some designs for the four suggested filters and
>>>>>>>>> >> build
>>>>>>>>> >> some prototypes and
>>>>>>>>> >> stick the results on the wiki.
>>>>>>>>> >>
>>>>>>>>> >> We can then decide and discuss what we think we should do.
>>>>>>>>> >>
>>>>>>>>> >> M
>>>>>>>>> >> ------------------------------------------------------------------------
>>>>>>>>> >> From: Ashhar Farhan <mailto:farhanbox@xxxxxxxxx>
>>>>>>>>> >> Sent: 01/02/2014 05:00
>>>>>>>>> >> To: minima@xxxxxxxxxxxxx <mailto:minima@xxxxxxxxxxxxx>
>>>>>>>>> >> Subject: [minima] Re: Linear Output Filter Switching
>>>>>>>>> >>
>>>>>>>>> >> Mark,
>>>>>>>>> >>
>>>>>>>>> >> I have been mulling over this ... and I am trying to balance quite
>>>>>>>>> >> a
>>>>>>>>> >> few things here.
>>>>>>>>> >>
>>>>>>>>> >> 1. Can we make do with just four filters? I have attached a
>>>>>>>>> >> screenshot
>>>>>>>>> >> of a simulation I ran (both these programs are available on the
>>>>>>>>> >> EMRFD
>>>>>>>>> >> CD). As you can see, a filter can be cut for 7 and 10 mhz. The 7
>>>>>>>>> >> mhz's second harmonic at 14 is down by 25db. Which means, if we
>>>>>>>>> >> don't
>>>>>>>>> >> distort the linear too much, we can get more 43 db suppression of
>>>>>>>>> >> the
>>>>>>>>> >> harmonics. If you guys agree to this , then, I propose as follows
>>>>>>>>> >> :
>>>>>>>>> >> 1st filter for 3.5 MHz
>>>>>>>>> >> 2nd filter for 7-10 mhz
>>>>>>>>> >> 3rd filter for 14-18 mhz
>>>>>>>>> >> 4th for 21-28 mhz
>>>>>>>>> >> These will have to be
>>>>>>>>> >> three section filters, which is alright. A
>>>>>>>>> >> 1-of-4 decoder like 74LS139 could do the switching with just 2
>>>>>>>>> >> lines.
>>>>>>>>> >>
>>>>>>>>> >> 2. The switching of the main filters is at variance with this
>>>>>>>>> >> scheme.
>>>>>>>>> >> so, we will have to use a dedicated line (as we are doing now) to
>>>>>>>>> >> switch these filters.
>>>>>>>>> >>
>>>>>>>>> >> 3. There is a third line A0 (pin 23) that is unused. this can be
>>>>>>>>> >> used
>>>>>>>>> >> to switch in a higher bandwidth filter (more than 10 Khz). with
>>>>>>>>> >> this
>>>>>>>>> >> filter, the broadband audio can be fed to an 'SDR' back-end like
>>>>>>>>> >> linrad. The serial port can provide the tuning control.
>>>>>>>>> >>
>>>>>>>>> >> - f
>>>>>>>>> >>
>>>>>>>>> >>
>>>>>>>>> >> On Sat, Feb 1, 2014 at 7:01 AM, Dan Reynolds <on30ng@xxxxxxxxx
>>>>>>>>> >> <mailto:on30ng@xxxxxxxxx>> wrote:
>>>>>>>>> >>
>>>>>>>>> >> 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
>>>>>>>>> >> <mailto: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 <mailto: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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