[johnnyvd]

Luke,

I just ordered the TCB, Sound and Scout PCB's at OSH Park.
Getting ready to build some control units!

But the strange thing is when i look at the TCB BOM list under the ICs section almost all quantities are set to zero?
Why is that? Can i trust the rest of the BOM? How many ATMEGA2560-16AU should i order

Cheers, John

[LukeZ]

My apologies, and thanks for the catch. Those BOM files are pared-down versions of a more detailed file that listed alternate sources, and some lines were not corrected in the translation. In fact the quantity for each IC should be 1.

I've updated the BOM files on the Downloads page, and yes, you can trust the rest of the quantities!

HobbyKing has told me they've received stock of the TCB in their warehouse, they just need to post it on the website which could be anytime, maybe in the next week. So unless you really want a PCB project you could just wait to buy it assembled. The Scout and Sound boards are much easier to build than the TCB.

[johnnyvd]

Ah, thanks.. Sorry about doubting the rest of the BOM. But as i am working in the engineering business, i learned to be cautious when a BOM has some small issues..

Great to hear that Hobbyking is starting to produce the TCB. Maybe i will wait with ordering the parts for the TCB.

Also, i think you can become really proud about your work because today i received message from OSH park that my order was Automatically upgraded to Super Swift Service because there where 58 other orders totalling 300 boards for the Sound, TCB and Scout EACH!

Congratulations! (could you autograph my TCB please?? )

[LukeZ]

Wow, that's strange, I wonder if that was a typo on their part because I can't imagine that many people wanting to build these things. Their emails do state how many other customers are on the same panel just for curiosity's sake, but that doesn't mean the other customers are getting the same PCBs. But who knows! OSH should be giving me commission if that's true.

One thing to note, OSH Park uses a different supplier for their swift service. Electrically their boards are just as good but they use a lower resolution silkscreen than the normal (slow) supplier. Some of the smaller writing on the board may therefore be unreadable or blurry-looking. It's not a big deal, mostly just a cosmetic difference, but something to know.

[johnnyvd]

Guess what came in today!



Very fast delivery from OSH park.. Bad photo, but Silkscreen resolution seems perfect!
Now if i only ordered the components by now...

[johnnyvd]

Small problem with Digikey.. W25Q128FVSIG-ND is not available.. And backorder not allowed.
Any suggestions for alternative?

Is the W25Q128JVSIQ usable?

Oh, and the center strip for the L298, this is only for heat dissipation i guess?

[LukeZ]

Thanks for catching that, parts are being changed all the time and keeping the BOM up to date can be a challenge. The alternate you listed will work, but I would get this one instead (same thing, just different packaging): W25Q128JVSIQ CT-ND. I've update the official sound card BOM with this new number.

You could also leave this flash chip off and the sound card will still work fine. To date the firmware is not using the flash memory for anything, and I don't know if it ultimately will or not. I just wanted it on there for testing in case it proves useful. It might, but so far I haven't needed it. The flash memory is not large enough to hold all the sounds we want, so even if we did use it, it would only be for a few sounds and the rest are still going to be on the SD card.

You are correct about the bare strip down the middle of the L298. Same goes for the huge patches under the motor driver ICs on the Scout. Hopefully you are comfortable with reflow soldering since there is no way to connect these pads conventionally with a soldering iron. Reflow was a little daunting to me at first but after trying it I found it was really even easier than hand soldering.

The only component I have routinely had problems with reflowing is the ATmega2560. Applying paste by hand is never very precise, I would always get shorted pins. I ultimately found it easier to do that chip by hand using a good flux (such as this decanted to an even finer needle) and a fine tipped iron.

[johnnyvd]

Hi Luke,

When i was looking into the swapping of the MOSFET i also tried to find places in Europe for parts to build the TCB myselves again. This because servicedesk@Hobbyking has no clue what, how and when they will get the new TCB boards, so when i get mine from Hobbyking i will never of my life turn it in again!

But now: cross reference for the TCB. A lot of the parts can be aquired here, some not and some have alternatives.

Mouser seems to have quite a selection except for the JST connectors. Conrad is missing a lot of the important stuff and Distrelec. Farnell UK has a lot of parts. But sometimes they only supply large quantities like complete reels..

I try to find more suppliers and alternative components here in Europe! Maybe you have some use for this list.. So i will post it here..

[LukeZ]

Thanks Johnny, that must have been a lot of work.

For whatever else it might be worth, I will post two other versions of the TCB bill of materials that are not on the Downloads page. They are the same list of items, but:

• The Detailed file includes DigiKey prices as well as total component cost in both small and medium quantities. It also lists a few alternate places to source the most expensive components (the ICs), although the links may or may not work because they constantly change. But you can search eBay, AliExpress, etc.. yourself.
• The Manufacturer file is a stripped down version with many parts lacking a part number all together. Those lacking a part number are components you should easily be able to substitute with any other equivalent value and form factor.

These two BOM files were provided to Hobby King in addition to the one that is publicly available. You can see on the Manufacturer file that IRLM2502s are specified explicitly so they should not have been substituted.

But actually if you know what you are doing you should be able to substitute even more than are permitted in the Manufacturer file, for example it would not be a problem to use different LEDs on the board although I told Hobby King not to. I was trying to be conservative and keep as many items under our control as reasonable. But if you are building your own and are knowledgeable about electronics there is a good deal of leeway. Very little about this circuit is critical or operating under some kind of fine tolerance.

[johnnyvd]

Wow, thanks Luke.. This really helps!

Maybe i'm pushing it, but do you also have these files for sound and scout?

[LukeZ]

It's no problem, this project is open source! I don't have a manufacturer version of the sound card file because that one is still in beta and hasn't been shopped to producers yet. But here are the rest.

Note also that component prices are always changing, so they may not be the same as shown in the files even if you go back and look at DigiKey.