I am obviously falling into the trap of the 317 being so ubiquitous and a genuinely fantastic performer that it's being taken for granted, and I'm trying to fix a problem that isn't there.
Big bypass caps across the set resistor and the output, with protection diodes. Check.
Big bypass caps across the set resistor and the output, with protection diodes. Check.
I would just use the National Semiconductor test circuit. Nothing more, nothing less. But it really isn't that critical.
Dave
Dave
http://datasheet.octopart.com/LM317T/NOPB-National-Semiconductor-datasheet-7275803.pdf
Page 9 Figure 3 is what I meant.
Also page 15 bottom right might be better is using an external reference? But I would put in the diodes and reference decoupling capacitor.
Dave
Page 9 Figure 3 is what I meant.
Also page 15 bottom right might be better is using an external reference? But I would put in the diodes and reference decoupling capacitor.
Dave
That was also my suggestion, and exactly what I did with my SP-10 suply- the caps can be quite a bit larger (100-220uF) which further reduces noise and impedance.
Thanks, yes input and output caps definitely. But not the 10uF C2, increasing that will damage the dynamics.
Dave
Dave
Huh, my dynamics seem to be intact. 😀
See the definitive Erroll Dietz paper- note particularly Figure 4 and what happens to the output impedance below 100 Hz when that adjust cap is oversized (his data show 10uF vs 1000uF).
It was in EDN (a paper publication). Reprinted as Appendix C in Bob Pease's "Troubleshooting Analog Circuits."
Dave, I believe this is the Dietz article SY is referencing. - http://electrooptical.net/www/sed/ErrolDietzRegulatorNoisePeaks.pdf
And this is the circuit you are suggesting -
That's what I'm thinking, with 220uF on the output.
And this is the circuit you are suggesting -
That's what I'm thinking, with 220uF on the output.
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This does appear to be correct. I'm sure when I measured start up, that a 10uF gave a faster response as the load changed a lot and quickly. I may have to repeat that and thanks to SY for highlighting this.
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No prob- many people don't realize how good those regulators can be if used properly (I sure didn't before reading Dietz!). The other interesting thing is performance changes with current draw; higher current out is a beneficial thing.
Isn't there some trick where you make R1 (Adj-Out) a different value than the suggested 240ohm for more current to be drawn? 150R or something thereabouts? The regulator need only supply 250mA...
I use 120R just because some lots of 317s didn't regulate without 10mA minimum draw. The no-load current draw is 1.25V/R1.
The Chasss has been sent to be refinished, my brother-in-law owns an automotive paint and body shop, he is going to prep and paint it, I merely need to decide on a color. Somebody has suggested Autoair colors 4584, but it would clash with the plinth.
These photos were made to assist me in the reassembly of the turntable, but I thought you may want to see them as well -
Switch assembly
Edge connector
Motor bottom
Strobe assembly
Mechanical brake
Various stand-offs on chassis bottom
Parts removed from chassis
Bare chassis
These photos were made to assist me in the reassembly of the turntable, but I thought you may want to see them as well -
Switch assembly
Edge connector
Motor bottom
Strobe assembly
Mechanical brake
Various stand-offs on chassis bottom
Parts removed from chassis
Bare chassis
So you're sticking with the original color...?
What color have you decided on the plinth?
It's never too late to opt for a custom color and maybe do some color matching with the power supply chassis.
Are you going to leave the original chassis as is?
A lot of things could be done underside to strengthen-damp it.
The boards leave enough space for you to work on.
A crucial thing is to damp the area around the "thrust plate".
With a bit of metal CNC work the screw on ball supporting thust plate could become
a vibration sinking ballast weight of sorts.
I have tried it and works wonders.
What color have you decided on the plinth?
It's never too late to opt for a custom color and maybe do some color matching with the power supply chassis.
Are you going to leave the original chassis as is?
A lot of things could be done underside to strengthen-damp it.
The boards leave enough space for you to work on.
A crucial thing is to damp the area around the "thrust plate".
With a bit of metal CNC work the screw on ball supporting thust plate could become
a vibration sinking ballast weight of sorts.
I have tried it and works wonders.
Hi Tim
Would you ask him if there are/were any issues with the chassis. And like how he striped it, how it was flattened, what primer, etc ?
I would like to get some done here but I am nervous, as others have tried and found the material not to be very pure, very porous and difficult to get stuff to stick to.
Your brother-in-law is much more likely to do the job properly !
Let us know ?
Thanks
Dave
BTW, was this the colour ? 😉
Would you ask him if there are/were any issues with the chassis. And like how he striped it, how it was flattened, what primer, etc ?
I would like to get some done here but I am nervous, as others have tried and found the material not to be very pure, very porous and difficult to get stuff to stick to.
Your brother-in-law is much more likely to do the job properly !
Let us know ?
Thanks
Dave
BTW, was this the colour ? 😉
Soundofvoid-
Not sure yet, but probably original or black.
Reconstituted Ebony
Chassis will be refinished, but how will be left up to my brother in law.
Some damping will be added to the chassis, likely dynamat
No current plans on modifying the bearing well cap, but have looked into it.
Dave -
I will relay the refinishing technique once I hear from him.
Yes, that's the color. 🙂
Not sure yet, but probably original or black.
Reconstituted Ebony
Chassis will be refinished, but how will be left up to my brother in law.
Some damping will be added to the chassis, likely dynamat
No current plans on modifying the bearing well cap, but have looked into it.
Dave -
I will relay the refinishing technique once I hear from him.
Yes, that's the color. 🙂