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SV Oscillator PCB group buy

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#101
dchisholm said:
Congratulations! Good work!

Please be careful with your verbal descriptions. You may need to re-calibrate your way of looking at things.

Those two pins ARE used for something! They are used to set the voltage gain of the instrumentation amplifier U8. It just so happens that leaving them open-circuit (i.e., no components connected to them) sets the voltage gain of U8 to 1 V/V. By connecting pin 2 to pin 3 (i.e., the short-circuit solder bridge) you set U8 to its maximum available voltage gain - something greater than 1000 V/V. (According to the formula in the Data Sheet the voltage gain would be infinite, but in reality the limitations of the physical part will limit the gain to something less than infinite.)

The part is specified to operate with voltage gains between 1 and 1000, so all bets are off regarding the part's behavior when the resistance between pin 2 and pin 3 is much less than 50 ohms or so. Operating with lower resistance between those pins, or even shorting them, is unlikely to cause damage to the IC.

Enjoy your new oscillator! It would be good to know if your unit has similar noise and distortion performance to Glenn's prototype.

Dale
Click to expand...

Thanks. Yeah, I meant that those pins didn't do anything in the circuit. Thanks for looking up that information!

I haven't gotten around to doing much with it yet (I have many irons in the fire as they say).
 
#102
Hi Dirk,
A second oscillator is adjusted and the consistency is striking, no differences. Well, that is from what I can see with my measurement setup.
Have you done any adjustments yet?
 
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#103
AKN said:
Hi Dirk,
A second oscillator is adjusted and the consistency is striking, no differences. Well, that is from what I can see with my measurement setup.
Have you done any adjustments yet?
Click to expand...

No, I have not had time. My wife's son has been visiting for 2 weeks now, and I have a lot of other projects that need attending. That's great that there is a good consistency in the design.

I'm also working on a distortion magnifier, as developed by Bob Cordell. I have some boards arriving soon, of my own design.
 
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