Building & Enclosing an XR-2206 Based Function Generator Kit

[MK14]

My 1973 Popular Electronics Super Sweeper

https://worldradiohistory.com/Archive-Poptronics/70s/1973/Poptronics-1973-10.pdf

Intersil 8038 FG IC

enjoy


Jon

I misunderstood your post.  When you said 'My', I thought you meant that you had built (as an electronics hobbyist), one of those frequency sweep generators.

I didn't realize you were part of the team of three, who designed, built and wrote the article for it, in the first place!
Almost 50 years ago, wow!

[rdl]

The XR2206 was discontinued in 2011, though the last production run could have been years before that. 20 years ago cloning/counterfeiting was not as prevalent, so there's a good chance the one you bought was real.

I too bought a XR2206 ftom Jameco 20 years ago, but just the IC. Based on the date code it was a clone, not the original chip.

[Barry A. Waters]

The XR2206 was discontinued in 2011, though the last production run could have been years before that. 20 years ago cloning/counterfeiting was not as prevalent, so there's a good chance the one you bought was real.

I too bought a XR2206 ftom Jameco 20 years ago, but just the IC. Based on the date code it was a clone, not the original chip.

I have five of these ICs now, 1 from the 20 year old Jameco Kit, 1 from the current Jameco kit, 2 from Jameco recently ordered a la carte and one in a recently purchased Elenco FG-500K kit. I guess I need to do a shootout?

I've seen a video on YouTube where it states (and shows) that running some 'clones' at 12V and above causes them to become unstable. I'm at 12V now and have not noticed any stability issues. As soon as I get a 2.1mm Male DC Power Connector so I can rig up a cable and connect a variable DC supply to my Magic Box, I can test this on all 5 ICs. Are there any other 'clone issues' folks have found that I could include in my poking around? Maybe build a second box using a Split Supply instead of a Single and see if that matters?

Barry

[MrAl]

The faster Chip was the max038. It had impressive specs for the time, but was relatively expensive when new, and than quickly disappeard. AFAIR Maxim relied on a relatively special process to get those parts manufactured and the company that provided it rather suddently terminated that process / plant.

Modern day DDS based generators have largely replaced the old style triangle VCO based ones.
For simple analog control the old style chip still has it's benefits. DDS based generator also have some principle limitations with the triangle waveform.  So it makes sense that the Chinese make a replacement - just be a aware of some limititations with the supply. AFAIK the maximum supply voltage is a bit lower than for the original.

Oh that's interesting i never looked into the reason for discontinuing the chip.  I wanted to build one with that chip at one time and could not find a supplier.  I guess there are some sold on the web now for a high cost.  Not sure if i need it anymore.
Yes the DDS type took over i think.  I have a small board i think it was $8 (USD) and it goes up to 40MHz sine and square, dont think it does triangle though.  The frequency increments are  based on a 32 bit programming word so the increments are very tiny providing for a large range of frequencies.

[MrAl]

The 3  knowns chips where  XR2206,  ICL8038, and the MAX038

At time Maxim MAX038 where given freely as samples ... surely did not help  selling them  

I saw a few  going up to 25$ a piece few years later, and now on Fleabay we see some prices examples  lolll

Yes i think i saw prices like that some 10 years ago, but that was long after i wanted to build one.  At that time i couldnt find any for sale anywhere.

[Kleinstein]

I remember the 038 because I thought about building one.  However it  first was hard to get one and later nearly impossible, so that stopped it.

DDS can do sine wave very good and with a comparator one can get a good rectangle as well. A few DDS chips offer triangle too, but with limited performance (e.g. more jitter, limited frequency) - the triangle and even more saw tooth shapre is tricky as a DDS, as the ideal of phase interpoaltion not longer works.

[Bud]

A few years ago at a local hamfest I pulled from a seller's junk bin a couple aluminum boxes that seemed to be part of vintage avionic or military equipment, with "Modulator" written on them. I bought them to use as RF enclosures for my projects. When I got home and opened them up, each of them had a board with  genuine XR2206 inside.   

[Barry A. Waters]

It seems that I see some glitch on the top part of the waveform (see two last screenshot).
Can you show this part of waveform with better time resolution?

Your eyes do not deceive you and they appear on BOTH the Sine and Triangle waves on the kit's highest Band setting (1kHz - 100kHz) and, apparently, all throughout that Band's Frequency Range for this particular IC (1 of 5 I have and, with this one being recently purchased, a likely candidate for being a 'Clone'). I don't see them on the lower three Band Settings.

I'm trying to compile a 'Clone Issue' list for the XR-2206CP ICs and will add this to it. Instability at 12V and above is the only other issue I've found that folks have actually experienced with the so-called 'Clones'. Pointers to other's reported issues (specific and not general 'it's wonky' complaints) would be much appreciated. Maybe there are a few common / repeatable issues that could easily be checked to see if you have a 'Good' one OR a 'Bad' one. That's my thinking anyway...

Barry 

[ledtester]

Guess I should build my kit to see if it has the glitch...

[MrAl]

It seems that I see some glitch on the top part of the waveform (see two last screenshot).
Can you show this part of waveform with better time resolution?

Your eyes do not deceive you and they appear on BOTH the Sine and Triangle waves on the kit's highest Band setting (1kHz - 100kHz) and, apparently, all throughout that Band's Frequency Range for this particular IC (1 of 5 I have and, with this one being recently purchased, a likely candidate for being a 'Clone'). I don't see them on the lower three Band Settings.

I'm trying to compile a 'Clone Issue' list for the XR-2206CP ICs and will add this to it. Instability at 12V and above is the only other issue I've found that folks have actually experienced with the so-called 'Clones'. Pointers to other's reported issues (specific and not general 'it's wonky' complaints) would be much appreciated. Maybe there are a few common / repeatable issues that could easily be checked to see if you have a 'Good' one OR a 'Bad' one. That's my thinking anyway...

Barry

That's usually caused by a quick change to the input of an op amp.  The op amp can not respond fast enough to make the output impedance near zero as the input pulse makes it's way around the op amp.  It also happens in roll your own triangle generators.  Only (partial) fix i think is to lightly filter the output.

[Barry A. Waters]

Guess I should build my kit to see if it has the glitch...

(Attachment Link)

By all means! :-)

Barry