Groups > sci.electronics.design > #452101

Re: Audio Generator or Function Generator? Which to get?

From	Martin Brown <'''newspam'''@nezumi.demon.co.uk>
Newsgroups	sci.electronics.design
Subject	Re: Audio Generator or Function Generator? Which to get?
Date	2017-03-16 10:09 +0000
Organization	Aioe.org NNTP Server
Message-ID	<oado9d$19o8$1@gioia.aioe.org> (permalink)
References	(1 earlier) <oa5out$n06$1@gonzo.alcatraz> <oa8cno$1c3m$1@gioia.aioe.org> <8fdec2a5-4ebc-4c77-a1af-c35826ba72a0@googlegroups.com> <oabavn$18uf$3@gioia.aioe.org> <1b5646e2-75db-43ad-96ec-e5d18c21452e@googlegroups.com>

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On 15/03/2017 12:39, tabbypurr@gmail.com wrote:
> On Wednesday, 15 March 2017 12:10:36 UTC, Martin Brown  wrote:
>> On 14/03/2017 13:58, tabbypurr wrote:
>>> On Tuesday, 14 March 2017 09:22:05 UTC, Martin Brown  wrote:
>>>
>>>> There used to be old school analogue function generator chips
>>>> that made a triangle wave and then applied diode shaping to get
>>>> a pseudo-sine wave. HP made one design implementation that was
>>>> surprisingly good. Intersils 8038 was the poor mans alternative
>>>> for DIY.
>>>>
>>>> http://www.intersil.com/content/dam/intersil/documents/icl8/icl8038.pdf
>>>
>>>>
>>>
>>>>
I built one of those decades ago. What a car crash. The wave forms
>>> were hopeless. I don't remember the details to know why, I
>>> presume the problem was the 8038 though.
>>
>> It was never anything like as good as a Wein bridge sine wave but
>> it was good for about 0.5% THD if you trimmed it properly. I
>> suspect manufacturing tolerances made it inconsistent batch to
>> batch.
>>
>> Cute chip in its day, but that was a long time ago.
>
> I doubt it managed 50%, let alone 0.5%. It had 3 outputs, sine square
> & triangle. At some frequencies one output looked more like one of
> the others should, and the others were just a mess. It was dire, and

I built one a long time ago. I found it in my parents attic whilst 
clearing the house recently. I might test it to see how good/bad it is 
next time I have chance. You have inspired me not to just throw it out.

> yes I followed the advised circuit. It might manage 0.5% at some
> frequency, but as a sig gen it was a real failure. If I ever get the
> time I'll look at it again one day, it's on a shelf somewhere.

It was fine as a rough sine wave over the audio range as long as you 
were not trying to measure hifi amplifier distortion. The tweak in fig 4 
would trim THD to <1% over most of the audio range at least it did for 
me. Symmetry of the triangle waveform was essential to minimising THD - 
most of the errors did not come from the sine shaping network.

-- 
Regards,
Martin Brown

Thread

Audio Generator or Function Generator? Which to get? oldschool@tubes.com - 2017-03-13 02:26 -0600
  Re: Audio Generator or Function Generator? Which to get? Colin Horsley <horsley-spam@westnet.com.au> - 2017-03-13 20:20 +1100
  Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-13 02:20 -0700
  Re: Audio Generator or Function Generator? Which to get? Jasen Betts <jasen@xnet.co.nz> - 2017-03-13 09:32 +0000
    Re: Audio Generator or Function Generator? Which to get? Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2017-03-14 09:22 +0000
      Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-14 03:11 -0700
      Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-14 06:58 -0700
        Re: Audio Generator or Function Generator? Which to get? Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2017-03-15 12:10 +0000
          Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 05:39 -0700
            Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-15 17:41 -0700
              Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 19:13 -0700
                Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-15 19:23 -0700
                Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 19:32 -0700
                Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-15 19:44 -0700
                Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 21:00 -0700
                Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-15 22:09 -0700
            Re: Audio Generator or Function Generator? Which to get? Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2017-03-16 10:09 +0000
            Re: Audio Generator or Function Generator? Which to get? "David Eather" <eather@tpg.com.au> - 2017-03-17 13:56 +1000
              Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-16 22:44 -0700
              Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-17 02:35 -0700
                Re: Audio Generator or Function Generator? Which to get? Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2017-03-17 11:28 +0000
                Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-17 11:10 -0400
          Re: Audio Generator or Function Generator? Which to get? George Herold <gherold@teachspin.com> - 2017-03-15 07:13 -0700
  Re: Audio Generator or Function Generator? Which to get? Ralph Mowery <rmowery28146@earthlink.net> - 2017-03-13 10:13 -0400
  Re: Audio Generator or Function Generator? Which to get? "dcaster@krl.org" <dcaster@krl.org> - 2017-03-13 09:09 -0700
    Re: Audio Generator or Function Generator? Which to get? Jasen Betts <jasen@xnet.co.nz> - 2017-03-13 18:59 +0000
      Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-14 19:43 -0400
        Re: Audio Generator or Function Generator? Which to get? krw@notreal.com - 2017-03-14 20:50 -0400
          Re: Audio Generator or Function Generator? Which to get? "dcaster@krl.org" <dcaster@krl.org> - 2017-03-14 18:34 -0700
            Re: Audio Generator or Function Generator? Which to get? krw@notreal.com - 2017-03-14 21:48 -0400
          Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 05:43 -0700
            Re: Audio Generator or Function Generator? Which to get? "dcaster@krl.org" <dcaster@krl.org> - 2017-03-15 07:30 -0700
              Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 11:36 -0700
            Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-15 17:46 -0700
              Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 19:15 -0700
                Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-15 19:26 -0700
                Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 19:45 -0700
                Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-15 20:15 -0700
                Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 21:05 -0700
                Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-15 22:24 -0700
                Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-16 10:07 -0700
                Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-16 14:06 -0400
                Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-16 15:37 -0700
    Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-13 17:43 -0700
      Re: Audio Generator or Function Generator? Which to get? "dcaster@krl.org" <dcaster@krl.org> - 2017-03-14 06:46 -0700
        Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-14 07:01 -0700
          Re: Audio Generator or Function Generator? Which to get? "dcaster@krl.org" <dcaster@krl.org> - 2017-03-14 08:51 -0700
            Re: Audio Generator or Function Generator? Which to get? amdx <nojunk@knology.net> - 2017-03-14 11:13 -0500
            Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-14 16:20 -0700
        Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-14 17:47 -0700
  Re: Audio Generator or Function Generator? Which to get? Jeff Liebermann <jeffl@cruzio.com> - 2017-03-13 09:27 -0700
    Re: Audio Generator or Function Generator? Which to get? oldschool@tubes.com - 2017-03-13 14:23 -0500
      Re: Audio Generator or Function Generator? Which to get? Ralph Mowery <rmowery28146@earthlink.net> - 2017-03-13 16:28 -0400
      Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-14 19:57 -0400
        Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 05:46 -0700
          Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-15 12:36 -0400
            Re: Audio Generator or Function Generator? Which to get? tabbypurr@gmail.com - 2017-03-15 11:38 -0700
            Re: Audio Generator or Function Generator? Which to get? Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2017-03-16 12:52 +0000
              Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-16 12:53 -0400
  Re: Audio Generator or Function Generator? Which to get? amdx <nojunk@knology.net> - 2017-03-13 13:43 -0500
    Re: Audio Generator or Function Generator? Which to get? amdx <nojunk@knology.net> - 2017-03-13 14:01 -0500
    Re: Audio Generator or Function Generator? Which to get? oldschool@tubes.com - 2017-03-13 14:33 -0500
      Re: Audio Generator or Function Generator? Which to get? amdx <nojunk@knology.net> - 2017-03-13 14:51 -0500
      Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-14 20:02 -0400
  Re: Audio Generator or Function Generator? Which to get? "Benderthe.evilrobot" <Benderthe.evilrobot@virginmedia.com> - 2017-03-13 21:15 +0000
  Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-14 14:31 -0400
    Re: Audio Generator or Function Generator? Which to get? whit3rd <whit3rd@gmail.com> - 2017-03-14 17:23 -0700
      Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-14 20:52 -0400
        Re: Audio Generator or Function Generator? Which to get? whit3rd <whit3rd@gmail.com> - 2017-03-14 18:24 -0700
          Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-14 23:26 -0400
            Re: Audio Generator or Function Generator? Which to get? whit3rd <whit3rd@gmail.com> - 2017-03-15 13:06 -0700
              Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-15 16:24 -0400
        Re: Audio Generator or Function Generator? Which to get? Jasen Betts <jasen@xnet.co.nz> - 2017-03-15 02:21 +0000
          Re: Audio Generator or Function Generator? Which to get? amdx <nojunk@knology.net> - 2017-03-15 07:24 -0500
            Re: Audio Generator or Function Generator? Which to get? rickman <gnuarm@gmail.com> - 2017-03-15 12:38 -0400
    Re: Audio Generator or Function Generator? Which to get? Phil Allison <pallison49@gmail.com> - 2017-03-14 17:53 -0700
  Re: Audio Generator or Function Generator? Which to get? Bill Beaty <billb@eskimo.com> - 2017-03-16 14:04 -0700
  Re: Audio Generator or Function Generator? Which to get? DemonicTubes <tlackie@gmail.com> - 2017-03-17 08:55 -0700
    Re: Audio Generator or Function Generator? Which to get? Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2017-03-17 16:10 +0000

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