A Crummy Commercial

 In November 2018 I purchased a couple of LM35 temperature sensors from ebay.  These are in a 3 lead TO-92 package and look like a transistor.  One lead is power, another is ground and the third is a voltage output, 10 mV per degree Celsius.  I had been using the LM34 temperature sensor with the same pinout but which has a Fahrenheit output so I wanted to try the Celsius version. who can tell just by looking if it's a fake ? These were my notes at the time:  " tried one, got hot (smoke), then tried an LM34, it was OK " I tried plugging the other one into one of those LCD based component testers, it indicated it was a dual diode, so not even a transistor ? In other words, it's FAKE.  Three strikes and you are out !  No more trying to get bargains on ebay.  I did get my money back but yikes, smoke !  It's one thing to have something fail but another to actually be potentially dangerous ! BTW this is another chip that is out of stock at both Dig...

I bought some LM2936 5 volt voltage regulator chips on ebay in 2014.  At that time the LM2936 sold for something like $1.36 in quantity 100.  Now they are over $2 in quantity 100 if you can find them (2023 arrival dates on Mouser).  They are an expensive part, see https://wb9kzy.blogspot.com/2022/02/ldo-regulator-ic-chips.html These ebay parts were 11.50 for 20, less than 1/2 price.  After I got them I could see they sorta looked genuine except the date code was only 4 digits instead of 5: looks OK but does it work ? as compared to the real ones: the genuine chip And they did seem to regulate, with a 5 volt output.  But the problem was the Iddq quiescent or idle current.  The real ones are about 7 uA with a 9 volt input: 7 uA for genuine LM2936 These fakes were 62 uA at 9 volt input: 62 uA for fake LM2936 With 9 times the idle current they must be some other regulator chip laser marked to be the "top shelf" item.  I didn't bother trying the reverse bia...

 There really are people who sell fake chips.  They might not know that they are fake but obviously someone along the supply chain knew they were fakes. I blame the recent uptick in IC fakes on laser marking.  It's relatively easy for someone to connect a laser marker to a PC and generate a pretty convincing mark on an IC. However sometimes they slip up.  An example:  the MC12080 prescaler chip.  This is an ECL chip meant to divide frequencies from say 200 MHz to 1600 MHz by a factor of 10 (other factors are pin programmable).  I used this chip in the Prescaler kit. http://wb9kzy.com/prescalr.htm The real chips are from onsemi which used to be ON Semiconductor (and was originally part of Motorola) and look like this (this one is from Mouser): When viewed from farther back there is what appears to be a white stripe on the left, it's really just 6 vertical lines "drawn" by the laser marker. But I've tried some of the ebay vendors of this chip and gotten ...