bad CA3280 dual OTA's

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Indeed, and some kits that need them are sold without them, so I guess his stock is really low.

TekniK · Joined: Aug 10, 2008 Posts: 1059

a quick google search and i found them,no problem there are much enough left.

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Care to enlighten us on that source?

I found some at www.dil.nl. These are the original RCA version. Pretty expensive and at least 25 years old (and my experience with the longevity of RCA chips isn't that good...)

magman · Joined: Feb 04, 2009 Posts: 363 Location: Liverpool, UK

Using this nice little web tool:

http://burnit.co.uk/sdiy/part_search.php

I found CA3280's at Cricklewood Electronics and Nikko that appear to be in stock currently.

And from this site:

http://electronicpool.de/en/index.html

They appear to have small volumes that you can request quotes for, including what appear to be original Harris devices.

Good hunting

Regards

Magman

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Thanks for that.

Cricklewood don't ship outside the UK. Nikko do, but they state "For obsolete products please call and check availability" below the CA3280 entry, so I'll probably better ask first before sending them any money.

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

DIL are being very rude by the way. They are not answering my questions in their e-mail replies and don't seem to be interested in my order in any way. So I won't buy from them.

frijitz · Posted: Wed Jun 10, 2009 8:46 am Post subject:

TekniK · Joined: Aug 10, 2008 Posts: 1059

frijitz · Posted: Wed Jun 10, 2009 11:03 am Post subject:

Over 20,000 here:
http://www.1sourcecomponents.com/search/search.htm

And over 50,000 here:
http://www.summitelectronics.com/search.html

Listed, at least.

Very Happy

Ian

TekniK · Joined: Aug 10, 2008 Posts: 1059

camelneck · Joined: Sep 27, 2008 Posts: 68 Location: KY (USA)

I didn't buy any of the CA3280's from Futurlec, did I have bought about 20 of the LM394's from them within the past 6 months. The last batch (8 LM394's), which I bought about 3 months ago, looked very peculiar as if some may have been used (pulled). Although I have not used or tested any of these yet, let me explain why they look suspicious.

1) Normally, when I buy a batch of chips from a major supplier, I expect most of the chips within that batch to look very similar, but no two chips in this last batch of 8 look alike although they all appeared to be made by the same manufacturer. (Each IC has the same manufacturer's logo. It looks like two rising ramp waves on top of each other.)
a) At least, 5 of these 8 IC's have varying degrees of body wear. (I define body wear as scratches, scuffs, and abrasions to the black plastic case.)
b) Except for the 3 IC's that have the brightest, whitest text and graphics, the 5 other ICs show varying degrees of text wear. (Bright white, white, white with some fading, white but half faded).
c) Of those 3 IC's that have the brightest, whitest text, not only is the color of the text whiter, the font of the text is also larger!! Each of these ICs also appear to have scuffs surrounding (and even underneath) the text. (I could also see these scuffs inside closed numbers, such as 8's and 0's.)
d) Although all 8 IC's have a white band running from pin 1 to pin 8, on 5 of the IC's the width of this band extended to the top edge of the IC. This included the 3 IC's that had the larger text font. (The width of this band didn't extend to the top edge on the other 3 ICs.)
e) Although each chip has 3 rows of text, the text in the top row, such as "8836A", is unique to each chip. (The text in the middle row is "LM" on all 8 chips. The text in the bottom row is "394CN" for all 8 chips.)

I have heard rumors that some Chinese businesses take similar (but not identical) ICs (including cheap substitutes made in China), sand the numbers off them, and paint new numbers on the chips. This could explain the scuffs around the text and why the text on these 3 ICs appear to be so much whiter than the rest. However, I have no expertise in this matter so I don't know what to think. I only know what I see or "smell". (I once bought some chips from Parts Pipe that smelled like they had been soaked in Diesel fuel.)

About 2 months ago, I was lucky enough to find a company that had 20 LM394CH metal cans left for $3.50 each. I eagerly bought all of them up. When I run out, I will probably use only SSM2210s.

However, if Futurlec ever gets some more of the $1.80 CA3280's in stock, I'll probably buy 20 of them. If only 2 out of every 9 CA3280's are bad, and the other 7 prove to be reliable, I would say that this is a good deal since they seem to cost about $12 each when you can find them (unless you buy them from Parts Pipe on Ebay.)

David

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

you can get 3280s here for $5 a pop

http://cgi.ebay.com/CA3280-CA3280E-Transconductance-Amplifier-DIP_W0QQitemZ150348385195QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2301764bab&_trksid=p3286.m20.l1116

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Fernando · Posted: Mon Jul 27, 2009 8:36 am Post subject:

Just be careful with those component tracers (usually from Asia, often with an USA office. Don't be fooled)
When the price is right they want extraordinary shipping charges or they tell you they have stock but they don't and communication is noisy and tedious. And they keep sending you e-mails after you say you are not interested. They even ask you if your wife and family are fine and insist maybe for some months.
This is my experience.

cheers to all synth DIYers