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Old Dec 28, 2012, 01:26 PM
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I can't understand why you would want to go w/ a different OSD when Dennis has put all the work into this? Don't let the smt assembly intimidate you, it is not hard at all. I have built down to 0402 at home (w/ microscope) - could do 0201 but just don't have a project that is 0201, 0603 w/ no microscope, a hotplate and a infra-red thermometer with great success. Dennis built w/ 0805 & 1206 size components to make it easy - trust me, it is not hard, the most of an issue you will run into are shorts on the exposed legs of the max7456 & atmega328 which is easily rectified w/ a soldering iron and some de-soldering braid.
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Old Dec 28, 2012, 02:07 PM
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..... it is not hard at all.......
I'm ready !

Just waiting for Dennis to say he is ready for someone to test the board. No hurry!
Then a updated detailed parts list with vender, maybe price, to order all together and get it right the first time.
Then thinking maybe a little guidance on what goes where.

No hurry, currently waiting for an "updated" radio to assign channels to test Dennis's menu.

Rick
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Old Dec 28, 2012, 02:07 PM
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Yes, the 0805 components should be pretty easy to solder.
I personally prefer 0603 for normal resistors, caps etc. but they require a little practice if you have never soldered SMD before.

But I gotta admit, that the MAX7456 chip is not really beginner-friendly.

All the components for the OSD (without MAX7456 IC, but with PCB) is around 10-15$, so it should be acceptable even if you don't get it right the first time
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Old Dec 28, 2012, 02:09 PM
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Just need the BOM list! The station already warming up...
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Last edited by IceWind; Dec 28, 2012 at 02:36 PM.
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Old Dec 28, 2012, 02:12 PM
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Sounds great guys
I'll make some better documentation of PCB, components etc. when it have been tested. I think the PCB is in my mail-box, but I haven't been home for a few days.
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Old Dec 28, 2012, 02:24 PM
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This should not be taken as a final BOM, but should give a good indication of the approximate price...
(Just ignore the danish text, and print = PCB)
https://dl.dropbox.com/u/3947315/OSD_price.pdf
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Old Dec 28, 2012, 02:33 PM
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Dennis,

I would be willing to turn the BOM into digi-key part numbers - just lmk. FWIW I personally always build w/ 1% resistors and 10% caps in whatever type needed. I think it is going to be majority x7r, npo for the caps for the crystal and then a couple tantalum 1206 units.
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Old Dec 28, 2012, 03:49 PM
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Quote:
Originally Posted by bob4432 View Post
I can't understand why you would want to go w/ a different OSD when Dennis has put all the work into this? Don't let the smt assembly intimidate you, it is not hard at all. I have built down to 0402 at home (w/ microscope) - could do 0201 but just don't have a project that is 0201, 0603 w/ no microscope, a hotplate and a infra-red thermometer with great success. Dennis built w/ 0805 & 1206 size components to make it easy - trust me, it is not hard, the most of an issue you will run into are shorts on the exposed legs of the max7456 & atmega328 which is easily rectified w/ a soldering iron and some de-soldering braid.
For me its not the difficulty soldering, its just that the MAX7456 chip alone is $17 on digikey. Add to that a PCB and extra parts and you are probably at $30 or $40. And a lot of soldering time. Its just easier to buy one already made.

Dennis I believe I read somewhere in this thread that the character set is not right on the Minim OSD. Could you please clarify this? Thanks!
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Old Dec 28, 2012, 05:50 PM
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Dennis,

I would be willing to turn the BOM into digi-key part numbers - just lmk. FWIW I personally always build w/ 1% resistors and 10% caps in whatever type needed. I think it is going to be majority x7r, npo for the caps for the crystal and then a couple tantalum 1206 units.
That would be great
I'll post a detailed BOM and further info when I get home and have a little time to test the new PCB.

Thanks!
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Old Dec 28, 2012, 06:20 PM
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That would be great
I'll post a detailed BOM and further info when I get home and have a little time to test the new PCB.

Thanks!
excellent, i am about done w/ what you posted - changed the caps for the crystal to 18pf per the ds but other than that, same as you posted
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Old Dec 28, 2012, 08:19 PM
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excellent, i am about done w/ what you posted - changed the caps for the crystal to 18pf per the ds but other than that, same as you posted
Sounds good
But I think 22pF is a better choice.
Cl = (22pF * 22 pF) / (22pF + 22pF) + Cs = 11pF + Cs.
Aiming for 18 pF, and with an estimated stray capacitance around 5 pF, that will give 16 pF.
The atmel design note suggests 5-10pF stray-capacitance which gives 17.5 pF using 2 x 22 pF load caps.

Using 2 x 18pF caps will give an estimated load-capacitance at 14pF (with 5 pF stray capacitance), which is a bit further from the suggested 18pF from datasheet.

Both should work, but a quick calculation suggests 22 pF or more.

Atmel design notes:
http://www.atmel.com/Images/doc2521.pdf
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Old Dec 28, 2012, 09:22 PM
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no probs, i went off the crystal ds, so back to 22pF

digi-key has a weird way of sharing BOMs, so here is the list so far if anybody wants to verify it:
MAX7456-DIY-OSD-NOT-FINAL

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Sounds good
But I think 22pF is a better choice.
Cl = (22pF * 22 pF) / (22pF + 22pF) + Cs = 11pF + Cs.
Aiming for 18 pF, and with an estimated stray capacitance around 5 pF, that will give 16 pF.
The atmel design note suggests 5-10pF stray-capacitance which gives 17.5 pF using 2 x 22 pF load caps.

Using 2 x 18pF caps will give an estimated load-capacitance at 14pF (with 5 pF stray capacitance), which is a bit further from the suggested 18pF from datasheet.

Both should work, but a quick calculation suggests 22 pF or more.

Atmel design notes:
http://www.atmel.com/Images/doc2521.pdf
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Old Dec 29, 2012, 06:38 AM
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Great, I can do the same for Farnell as I usually order all parts from them.
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Old Dec 29, 2012, 06:41 AM
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Originally Posted by bob4432 View Post
no probs, i went off the crystal ds, so back to 22pF

digi-key has a weird way of sharing BOMs, so here is the list so far if anybody wants to verify it:
MAX7456-DIY-OSD-NOT-FINAL
Thanks a lot Bob
I have a few changes for decoupling caps, but lets take it when I've soldered the new PCB and everythig have been tested.

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Great, I can do the same for Farnell as I usually order all parts from them.
I already have a farnell-list as I'm ordering from Farnell. Will post later
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Old Dec 29, 2012, 08:45 AM
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looking at BOM, I'm wondering how they are able to make so cheap minimOSD - HK sells it for 18.99, but you can get it for 16.88 shipped on ebay - and it has atmega328 and MAX7456 in it.
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