Low-distortion Audio-range Oscillator - Page 389 - diyAudio
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Old 16th July 2014, 03:15 PM   #3881
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Quote:
Originally Posted by 1audio View Post
Needs an adapter but may be the best available quad opamp for this application: LME49740 | Audio Operational Amplifier | Audio | Description & parametrics A quick survey turned up nothing else similar.
Okay,

I found it with your link, thanks Demian. I should get the 14 pin dip
and a socket for it. Now sure what board it needs, hmmm.

Is there an advantage with the SOIC vs. 14DIP that I don't know about?

From the link also TI recommends the $1.70 price for the unit. I wonder why
the reviewers are complaining about that price, what do they want? Surplus store
IC pricing? .25 - .99 $ a chip?

Then I'm not sure if Richard is alluding to using the TLC2274 and the MLT04 in
different places. Where to those go in the HP339a?

I just want to make sure I don't put the chops in the wrong places. I am going to sub the 14 pin one on the Main osc board A1, right after (or before the U2 JFET. ) on the schematic is the U2C, U2B, U2A.

On the P/O A4 board:
P/O A4 U5A, U5B, U5c, U3a, U3b, U3C, U6a, U6b, U6c, U6d.
I Think I got that right. Use the same quad opAmp?

Now I'm confusing myself, I'll have to think this through just a bit more.
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Old 16th July 2014, 04:26 PM   #3882
1audio is offline 1audio  United States
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Quote:
Originally Posted by simon7000 View Post
Demian,

The problem with that kind of adapter is the final width is not .3"

ES
If it is available as a PDIP its not an issue. No need for an adapter. I'll read the whole datasheet next time. Unit price of $4.28 is not bad. Get samples from TI as the first option. DC offset is 100 nV typical so it should just drop in.

I would get one of Viktor's oscillators as a reference so the calibration/nulling process can proceed. Ultra Low Distortion 0 00001 1kHz Sine Generator Assembled and Tested PCB | eBay Its really hard to optimize both a generator and an oscillator at the same time.
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Old 16th July 2014, 04:29 PM   #3883
RNMarsh is offline RNMarsh  United States
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LME49740 is available in 14DIP from DigiKey.

-RM
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Old 16th July 2014, 05:23 PM   #3884
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Quote:
Originally Posted by RNMarsh View Post
LME49740 is available in 14DIP from DigiKey.

-RM
Yes, But since I never admit mistakes, it has never happened to me that I clicked on the wrong item and got the SOIC and needed an adapter and found that really didn't work quite the same either!

So the only issue with the PDIP is that it has a much higher bandwidth and the wise will check to be sure it is not oscillating at say 55 MHz.
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Old 16th July 2014, 06:59 PM   #3885
davada is offline davada  Canada
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Quote:
Originally Posted by simon7000 View Post
Yes, But since I never admit mistakes, it has never happened to me that I clicked on the wrong item and got the SOIC and needed an adapter and found that really didn't work quite the same either!

So the only issue with the PDIP is that it has a much higher bandwidth and the wise will check to be sure it is not oscillating at say 55 MHz.
Oh yes. Do be careful with this. Hp on some revisions added 100 ohm resistors at the power pins before the bypass caps. With these high bandwidth op amp you night consider using a small OSCON. 6.8uF should do. You may also find it necessary to add a small R or ferrite bead at the output. The stray C can be a problem.

Just about anything has got to better than a 741.

What's a 'mistake'??? Oh I see, you mean inventory.
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Last edited by davada; 16th July 2014 at 07:03 PM.
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Old 16th July 2014, 07:04 PM   #3886
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What's a 'mistake'??? Oh I see, you mean inventory.
Something other people make.
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Old 16th July 2014, 09:36 PM   #3887
JimT is offline JimT  Canada
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Quote:
Originally Posted by 1audio View Post
I would get one of Viktor's oscillators as a reference so the calibration/nulling process can proceed. Ultra Low Distortion 0 00001 1kHz Sine Generator Assembled and Tested PCB | eBay Its really hard to optimize both a generator and an oscillator at the same time.
Thanks for the link, I was having trouble finding this. Got one on the way now.

Jim
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Old 17th July 2014, 02:30 AM   #3888
1audio is offline 1audio  United States
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Originally Posted by simon7000 View Post
Something other people make.
Remind me to never work for you.
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Old 17th July 2014, 03:59 AM   #3889
RNMarsh is offline RNMarsh  United States
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Once heard an argument like this ---- I have not made a mistake and I never have. And, I never will.

The man was successful and wealthy.

:-)

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Last edited by RNMarsh; 17th July 2014 at 04:01 AM.
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Old 17th July 2014, 06:39 AM   #3890
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You know it is interesting none of my friends make mistakes either. It is always somebody outside the circle. Although we will occasionally pull a prank on each other to see if they are paying attention.
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