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 >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> > >>