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 <mark.g0mgx@xxxxxxxxx> >> *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 <farhanbox@xxxxxxxxx>> >> >> Sent: 01/02/2014 05:00 >> >> To: minima@xxxxxxxxxxxxx >> >> <mailto:minima@xxxxxxxxxxxxx<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 <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 <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<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 >> >> >> >> >> >> >> > >> >> >> >> >> >> >> > >