Author Topic: Trying to find a 5032 8mhz crystal to use with an STM32F1xxx to buy from China  (Read 3016 times)

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Offline MarkM

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I hate to say it, but I've had great luck buying parts from China so far.  The issue is, you can find great deals, but usually at the expense of having to find datasheets and even part numbers yourself.  The reason for buying from China is simple.  The prices are sooo much cheaper.  I'm saving like $7 each board so far just buying the MCUs and USB ports from China to give you an idea. 

I was thinking of using some good old hc49 8mhz 18pf crystals, but they're just too big for my project.  I found these 5032 8mhz ones:

http://www.aliexpress.com/item/Free-shipping-100pcs-Passive-8M-5032-5-3-2-patch-8MHZ-8-0000MHZ-Crystal-4-feet/32359336289.html?spm=2114.01020208.3.2.wuxb0y&ws_ab_test=201556_10,201527_2_10_71_9_72_73_74_75_11_12,201409_1

Digging on Digikey, It looks very similar to this one:

http://www.digikey.com/product-detail/en/ABM3B-8.000MHZ-B2-T/535-9720-1-ND/1873254


My question is, without knowing the load capacitance, would you just start with 22pf caps first and scope it or ditch this idea altogether?

EDIT:If you have a better idea, that would be awesome as well.     


« Last Edit: September 27, 2015, 07:26:07 pm by MarkM »
 

Offline commie

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http://uk.mouser.com/Passive-Components/Frequency-Control-Timing-Devices/_/N-6zu9e?P=1z0wo7xZ1z0z7l5&Keyword=8mhz+crystal&FS=True

Buying from Mouser ensures the quality is top flight and in quantities of 50, they are 20pence each which is cheap.
 

Offline poorchava

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Why do you need 8Mhz? 16Mhz works same as well,  you'll only need to change PLL input divider value.

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Offline MarkM

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Commie, which ones are you talking about?  I saw a similar one at Mouser and they wanted way more than that.  I should've wrote all of that down.  I would much rather buy from Mouser/Digikey TBH, but lower quantities is just too expensive.  These little STM32 boards from China for like $4 total are pretty decent quality, actually.  No issues yet.

Poorchava, that works, but I still need to find some on the cheap.  Which ones do you guys use?  I'm trying to get this board as small as possible.  Think of teensy 3 size or so.
« Last Edit: September 27, 2015, 09:58:21 pm by MarkM »
 

Offline Brutte

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Quote
EDIT:If you have a better idea, that would be awesome as well.
Get the crystal-less USB chip.
Quote
I'm trying to get this board as small as possible.
WLCSP package then. Or bare die.
 

Offline MarkM

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I'll check it out, thanks!  I didn't realize that China is having a holiday.  Makes sense that I can't get anyone to respond right now.  I think from now on I'll just only order from sellers that respond and have datasheets.  Much better solution if you're going the Chinese route.
 

Offline Mechatrommer

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talking about digikey, i searched a chip and want to buy 3qty of it, $2 each, so $6 total so far so good, until i clicked estimate shipping cost by the cheapest courier (USPS), its $40 :palm: ironically i found the chip in ebay china more expensive at $4 each, i'm negotiating with the seller for $4 registered mail...

I hate to say it, but I've had great luck buying parts from China so far.  The issue is, you can find great deals, but usually at the expense of having to find datasheets and even part numbers yourself.
let me tell you a secret i discovered few hours ago while having the above experience... you find the spec and name evrything in the digikey parameteric table and hit the keyname in ebay china :P well thats not secret anymore, and i find that less ethical but... well i need to survive...
It's extremely difficult to start life.. one features of nature.. physical laws are mathematical theory of great beauty... You may wonder Why? our knowledge shows that nature is so constructed. We simply have to accept it. One could describe the situation by saying that... (Paul Dirac)
 

Offline ralphd

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2x6mm cylinder oscillators are almost as cheap as the hc49.
Unthinking respect for authority is the greatest enemy of truth. Einstein
 


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