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Jason Bowden

RC in Front of the Op-Amp: Why Did It Fail?

Jason Bowden
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goafrit2
goafrit2
1/24/2013 7:22:00 PM
User Rank
Master
Re: Fake parts
>> All of my PCBs and components came from Asia.

Now it makes sense. Largely, I do buy PCBs from Asia but never components. The reason is that they do not have companies that make components. It does not make a lot of sence to order PIC from Asia when Microchip Inc is here in USA. Yet, I have friends that do just that.

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eafpres1
eafpres1
1/23/2013 11:35:28 PM
User Rank
Blogger
Re: Fake parts
In the relatively early days of Satellite Radio commercial ramp up, there were a few parts used in the antenna amplifiers that were only made by certain companies in Japan, and they were often in short supply or on allocation.  This created a counterfeit market.  Since the antennas are roof mounted, these parts had to meet the broadest temp specs.  Often the counterfeit parts don't.  At one point I recall the design group testing a batch of ICs in the temp chamber to verify they were fake.

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Jason Bowden
Jason Bowden
1/23/2013 10:33:30 PM
User Rank
Newbie
Re: Fake parts
Thanks for the reply. Well first, let me say, I have had my run with fake components, op amps, triacs and LEDs. It is absolutely amazing how an electronic component can be counterfeited. I have a totally different story for the 3 fake parts I just mentioned, but let me try to give some advice in general overall. All of my PCBs and components came from Asia. The particular product we manufactured had such a high demand that year that it caused our CM to drain the distributor stock. This distributor was authorized and where they had purchased for years. They had to make an Emergency buy from a different distributor who was not authorized. Low and behold the entire single lot was fake. Basically, here is what I implemented and enforced that would at least help a little for me to always know where my parts came from. I made my CM put together a monthly report of only the major components to show where they were purchased, how many, datecodes, lot numbers and the datecode, lot number and production line the parts were used at the CM. also, I made certain that the CM would not buy from any different source until I was notified of who they were. I tried putting other controls in place, but some were too difficult.

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goafrit2
goafrit2
1/23/2013 9:14:14 PM
User Rank
Master
RC and Opamps
>> Since it focused my attention, in the end, perhaps putting an RC in front of the op amp was a good thing

Sure, one must look at the load issues and also the current that the opamp can provide to drive the resistor in the RC network. There is no general statement that having RC in front of opamps is always the best thing. It has to do with the circuit and the system. In yours it worked which is good.

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goafrit2
goafrit2
1/23/2013 9:09:45 PM
User Rank
Master
Fake parts
>> It was actually due to fake parts.

I am very curious - how did you end up with fake parts? Was it bought in Asia or through the normal U.S. distributors? I have never had that experience and will like to avoid it.

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<<   <   Page 4 / 4
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