Products > Dodgy Technology

Don't buy any kit with XR2206 WFG

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dbctronic:
Every once in a while, you need to bang up some little analog project and don't want to get stuck programming to drive a digitally controlled thingy. Sure, digital waveform generators there are, aplenty, but...

Anybody remember the venerable XR2206? Easy to use, full analog square/triangle/sine generator. Well, after they went out of production, one or more Chinese firms made knockoffs. There are still a few floating around, always with the date code 0489. You may see a little bright red board WFG kit, in particular. DON'T BUY!!!

This run of chips has a sine output that is only about 20 mV, with huge switching spikes that are impossible to filter out. I found out that this was a generally known problem.

I went on a tear last year looking for XR2206s, and in desperation bought a couple of such kits from several firms just to snag the chip. All had the bogus 0489 b******, and they all had the defective sine output. And the kit was perfectly useless without the 2206, of course. The kits were going for US$4 to 6, but when you add up several of these plus individual shipping and wasted time ...  |O

Time marches on...

Seekonk:
Like how hard is to copy a chip. I don't mind fakes as long as they work.  I use a number of IR2153 self oscillating half bridge drivers.  A feature I use is shorting the timing cap to turn both outputs off. This is a stated feature in the pdf.  These fakes turn off the hi side driver, but turn on the low side. If just generating AC that isn't a problem. My circuit becomes non functional. Now I never know what I will get when I order.

dbctronic:
Righto, Seekonk. If you stray from buying trustworthy parts, strongly consider playing it as plain vanilla as possible. A knockoff 2N3904 most likely has the standard base-collector-emitter pin order, but don't be surprised if some have a little below the minimum hFE, or burn up a little below VCE(max). These are minor fudges, but a blatant violation of specs such as you experienced is not, and more than once I've had similar designs in mind, especially trick enable/disable techniques such as yours, that would not have worked and would have required more redesign than it's worth.

I suspect that trick enable/disable designs are rather often subject to rude surprises. Annoying when making a one-off (  >:(  ), VERY annoying when in the middle of a production run (  :scared:  ).

Bud:
 If you need just one IC, drop me a PM. I have a NOS one that i can send.

ledtester:
When did Exar stop production? I see a lot of photos with a "F0919" date code, eg:



And some more variations:





And are the ones sold by Jameco fakes?

https://www.jameco.com/z/XR2206CP-EXAR-Corporation-IC-XR2206CP-Monolithic-Function-Generator_34972.html

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