[minima] Re: Parts list spreadsheet, still work in process

  • From: Jeremy Chase <jeremychase@xxxxxxxxx>
  • To: minima@xxxxxxxxxxxxx
  • Date: Mon, 17 Mar 2014 10:19:22 -0400

Ah - I see, the +5v bus was not explicitly added to the schematic. Good
catch.

--
Jeremy Chase
http://twitter.com/jeremychase


On Sun, Mar 16, 2014 at 12:46 AM, Thomas Sarlandie <thomas@xxxxxxxxxxxxx>wrote:

> Just looked at your spreadsheet. One more thing: You have a 78l05 on the
> RF board for the KISS mixer bias but you will also need a 7805 (to220
> package) for the arduino board. Make sure you put a heatsink on it. The LCD
> backlight uses a lot of current and that regulator needs to dissipate
> 12-5=7v * the current used by all your circuit.
>
> Do not share the same regulator for both functions.
>
>
>
>
>
> On Sat, Mar 15, 2014 at 9:41 PM, Thomas Sarlandie <thomas@xxxxxxxxxxxxx>wrote:
>
>> Jeremy,
>>
>> Great initiative! Some replies in text based on my experience building it.
>>
>> Hello,
>>>
>>> I've systematically gone through the schematic and made a comprehensive
>>> parts list from it. I'm hopeful this will be useful to both myself and
>>> others!
>>>
>>>
>>> https://docs.google.com/spreadsheet/ccc?key=0AkbVpmVim4O7dGM2SGZaYkJvTU1DNnloak1RZnpDZ2c&usp=drive_web#gid=0
>>>
>>> I still have many questions that I want clarification on though. If
>>> anyone can give more detail about the following please reply:
>>>
>>>    1. Is there a recommended inductor type for all of the filter
>>>    components? (A toroid type, etc.)
>>>
>>>
>> I have used what Mark recommended and just had to slightly adjust the
>> number of turns. Maybe because my magnet wire was smaller.
>>
>> I thought this information was on my website but nope :( I just added it.
>>
>> ValueQtyCoreN-Turns (Mark) N-Turns (Thomas).33 uH2T37-610 9.39 uH2T37-611
>> 10 .66 uH2T50-21210.78 uH 3T50-213113 uH3 T332524
>>
>>
>>
>>>
>>>    1. Can the 3u inductor near T3 be the same type as the inductors in
>>>    the filter?
>>>
>>> I guess you are referring to the inductor labelled "RFC" on Farhan's
>> schematic. Farhan said: "The RFC is 10 turns on FT37-43" According to
>> toroids.info, that is 35 uH.
>>
>> So no you cannot use the same inductors. And where did you get the value
>> 3uH?
>>
>>
>>>    1. What is the 'BAND SELECT' part connected to PD6 and PD7 of the
>>>    Arduino?
>>>
>>> This is a connector that would go to your power amplifier to switch
>> different band-pass or low-pass filters depending on the band that you are
>> on. The original idea was to use those 3 bits to select one band (3 bits =
>> 8 possibilities). We have since then explored other options and Farhan has
>> chosen the CD4017 option.
>>
>> Read "Bandswitching the low-pass filters" on the RF386 page for more info
>> on the new design that will only take one line:
>> http://www.hfsignals.org/index.php/RF386
>>
>>>
>>>    1. Can all 4 relays be of the same type? I know nothing about
>>>    relays; what should I be looking for?
>>>
>>> The two relays in the LPF and the relay in the BFO are SPDT. The one
>> that switches the audio and tx/rx (bottom of the schematic) is a DPDT. You
>> could replace it by two separate relays if you wanted to stick to just one
>> model.
>>
>> The most important characteristic is the voltage of those relays. Get 12v
>> dc relays. They should be adapted to small signals. Some are labelled for
>> "RF signals" and are a bit more expensive but I am not sure it makes a huge
>> difference for us.
>>
>> I have used BESTAR BS-102B for the LPF and the BFO. Bought them in a
>> surplus where they were the cheapest 12v small size relays. They seem cheap
>> online too:
>> http://www.alibaba.com/showroom/bs--102b--12vdc-bestar-standard.html
>>
>> For the DPDT I have used OMRON G6H-2.
>>
>> You can see pictures of them on my minima webpage.
>>
>>>
>>>    1. There are capacitors labeled "0.01" near Q20, but they don't have
>>>    a unit. What size are these capacitors?
>>>
>>> Micro Farads.
>>
>>>
>>>    1. There are unmarked electrolytic capacitors. One is near Q11; what
>>>    size are these unmarked electrolytic caps?
>>>
>>> I have asked about those a few times and did not get a clear answer. I
>> have read articles that claim that only the "+" symbols call for
>> electrolytics and that it is perfectly fine to use the curved+flat symbol
>> for ceramics. This matches what you see on the schema: the electrolytics do
>> have a "+" sign.
>>
>> I have used the same capacitors than everywhere else for those (0.1 uF).
>> I would love to hear from Farhan why some have a different symbol!
>>
>>>
>>>    1. There are electrolytic capacitors labeled +50, are these actually
>>>    50u?
>>>
>>> Yes. But I have used 47uF. Much easier to find.
>>
>>>
>>>    1. There are four 22p variable electrolytic capacitors; Are these
>>>    trim caps? Can I see an example? What am I looking for?
>>>
>>> Look on my pictures or mark's pictures:
>> http://www.sarfata.org/ham/images/minima-lpf-top.jpg
>>
>>>
>>>    1. I see 2 10k trim pots, a 1 turn 10k variable pot and a 1 turn
>>>    100k pot. Is this accurate?
>>>
>>> Yes. You might want to get a logarithmic pot for the 10k because it
>> controls the audio but the 100k must be linear.
>>
>>>
>>>    1. There is a crystal labeled 16M connected to X2 of the Arduino. Is
>>>    this a 16Mhz crystal?
>>>
>>> Yes.
>>
>> Enjoy!
>>
>> 73,
>> thomas
>>
>>
>>> Thank you very much!
>>> 73 de K2CHA
>>>
>>> --
>>> Jeremy Chase
>>> http://twitter.com/jeremychase
>>>
>>
>>
>

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