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View Full Version : Where I will get original crystals in Lamington Road



EmbeddedGuy
11-18-2007, 01:55 AM
Most of the crystals available in Lamington Road is duplicate chinees make. Any one knows the source from where I will get original crystal.
Or source in Pune.

docel
11-18-2007, 02:47 PM
So whats wrong with the chinese xtls?
They are OK, unless you have some tight tolerances.

Or
you can place a custom order with your specifications ( at several tens of the Chinese cost and a lot of time) from http://andhraelec.com/ They are quite good.

Also KELTRON used to make them .....
http://www.keltroncomp.com/kxl/index.html

Ulhas
11-19-2007, 10:23 PM
don't forget the crstal which you are saying are dupicate are the original product of the cmpany where it is manufactured.

so it does not matter dupicae or original what matters is Acuuray ,& the most important RELIABILITY.

Many of us are purchasing crystals frm laminton road hey and all of them have both of this


regards

ulhas

EmbeddedGuy
11-20-2007, 09:57 AM
Most of the crystals which are available in LR is KDS`s duplicate. Last time we have purchased same crystals of 4MHz and we tested the xtal using frequency counter and we found the frequency like 3.9MHz to 4.2MHz. There for we stop using those duplicate.

allbits
11-20-2007, 01:15 PM
What kind of application are you in, and what tolerance do you need??

I would also like to know how you tested the frequency of the crystal..

just curious...

docel
11-20-2007, 09:44 PM
Right Jobin!
I wanted to ask this same question but thought better of it.

It is just +/- 150Kc tolerance.........What do you expect ? for less than 10 bucks???

Besides, the load capacitances should be according to the Manufacturers datasheet. If unknown, then one of the two load caps can be made variable and the Crystal "pulled" to the desired freq. This is called 'netting' and is necessary even for 50ppm xtals.

I have pulled 50kcs out of a 50ppm crystal @ 8Mhz for my VFOs. ( they cost me around 250INR+taxes+post) whereas the cheap "duplicates" could be pulled to 250kcs (@3INR bulk).

Even TCXOs can be pulled...... :!:

A badly designed oscillator WILL pull the Xtal freq. due to stray capacitance, wrong loading and phase-shift. And if you did a "breadboard".... :roll:

EmbeddedGuy
11-20-2007, 11:01 PM
Projects are commercial and we can not use trimmer or any other capacitor for pulling the frequency. We are using 4MHz xtal for PIC microcontroller and faced this problem.
I know we can pull the frequency of xtal. I did these in experiment for crystal based oscillator for Tx/Rx application.

allbits
11-20-2007, 11:52 PM
We are using 4MHz xtal for PIC microcontroller and faced this problem.

Is it a time critical application?? Even though I might be deviating from the original topic, which was as to the availability and which I know nothing about, I would like to know the kind of applications that requires such tolerance, especially with a PIC. I guess UART or IIC or SPI will be happy with your tolerance..

debu
11-20-2007, 11:58 PM
For medical, aerospace or "Strict" real-time industrial applications, I prefer to use MAX038. Maybe it is what you require. For everything else I use local XTals. I once picked up a box of 1000 peices of XTals (Totally mixed, every size, shape, frequency), that box still serves me, its still half full :wink: and I never bought an XTal since.
I think we can all learn to improve our circuits, and reduce the impedence and noise. You can never get rid of it, but improve it a little, one PCB at a time. No need to blame it on the XTals.

docel
11-21-2007, 12:23 AM
Are you using the Capacitors??

allbits
11-21-2007, 12:37 AM
and MAX038.. guess they are no longer in production.. (just for the info - No wars intended.. :D )

Military grade applications calls for military grade components.. And PCBs matters.. There are guidelines for crystal placements, capacitor placements and ground plane placements. these need to be strict for precise operation..

Its one reason why asked as to the test set up- as to how the frequency was measured.

But its still a PIC @ 4 MHz. Should work.

EmbeddedGuy
11-21-2007, 01:36 AM
You can use and experiment with chines crystal for personal experiment and project. But cant use for commercial project. If it gives trouble at site it will cost you then. There for commercial product you have to use good quality crystal. Till date I haven't seen any commercial product manufacturer who use duplicate crystals. I am sure they are manufacturer who uses duplicate crystal but we can not follow them.

debu
11-21-2007, 08:46 AM
@Docel: Indeed, I believe rather then buy higher quality crystals, buy higher quality caps. :)

@allbits: MAX038CPP+ (Military/Aerospace/Medical Grade) is still being produced (I guess), I bought a batch of 50 in jan this year. Though its possible that they stopped production in the last couple of months. I can't seem to locate an equivalent IC from maxim anywhere. :)

@EmbeddedGuy: As I said before, I purchased a load of "local" crystals, I've used them all for industrial and commercial applications, and I have not recieved a single complaint.(Though none of them required any "Strict" real-time, as I mentioned before).

allbits
11-21-2007, 11:44 AM
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1257

again - this is for info!!!
:D

and the OP still refuse to give the smallest hint as to the application..
:(

guess the thread can now be locked...

debu
11-21-2007, 12:10 PM
@allbits: You're right!!


This product was manufactured for Maxim by an outside wafer foundry using a process that is no longer available. It is not recommended for new designs. For further information, contact us. The data sheet remains available for existing users.


Damn!!

docel
11-21-2007, 08:45 PM
Projects are commercial and we can not use trimmer or any other capacitor for pulling the frequency. We are using 4MHz xtal for PIC microcontroller and faced this problem.
I know we can pull the frequency of xtal. I did these in experiment for crystal based oscillator for Tx/Rx application.

WHAT ARE YOU SAYING??
Nobody designs a "commercial" circuit with high accuracy/reliablity without a 'netting' Trimcap.

If your application is that sensitive, then use a TCXO. Or just import them from Abracon or other 'hi quality' foreign manufacturers. ( Though the 'accurate'-expensive crystals fail to work with me on PICs until I balance the load.)

If it is such a hush-hush project, you should'nt be wasting our collective time with half-baked ideas and incomplete info. I suggest you read the PIC crystal oscillator specifications, in detail, as also about Crystals and Oscillators, in detail again. You should do this research very throughly, if you want to do any type of commercial, Industrial & professional design.

I also suggest you read the fine print given there even more throughly.

Allbits:
I dont see the relevance of this thread, but i'll leave it open for a while, since it is interesting and informative for others ( if not to embeddedguy). The Forum has very little on Crystals and this should be of help to others.

EmbeddedGuy
11-22-2007, 12:55 PM
If you read my post I asked ONLY the source of original crystal and I was not interested to know about the technical details of the crystal. But you guys start giving me suggestions. I just asked the source of original crystal not any other things.
Instead of showing me the source you started argument.

docel
11-22-2007, 03:07 PM
This is a ROBOTICS Technical Discussion Forum.
Not Google.
What did you expect? :lol: :lol:
Sorry , if it didnt help!