Burr Brown Chips

[apl]

I think the schematic I was using is wrong for the +48V section. The Cs are not doubling the V, and the 317 is not implemented properly.

 

[mshilarious]

I think the schematic I was using is wrong for the +48V section. The Cs are not doubling the V

I thought the caps had to be after half-rectifying the AC But again I don't see the need to double with 40VAC.

Edit: nah, maybe it's the way it's drawn. Something still doesn't look quite right, but I am only used to reading my own schematics

and the 317 is not implemented properly.

I haven't used 317 but cannabis' comments seem relevant here.

 

[apl]

I thought the caps had to be after half-rectifying the AC But again I don't see the need to double with 40VAC.

I do get >50V coming off the rectifier but I'm getting >50V off the transformer. Maybe the designer knew that would happen.

I haven't used 317 but cannabis' comments seem relevant here.

OK, another look makes me think the 317 is OK. Nuts.

And I was an EE major. Never used a lick of it since school.

I'm learning a lot.

 

[mshilarious]

I do get >50V coming off the rectifier but I'm getting >50V off the transformer. Maybe the designer knew that would happen.



OK, another look makes me think the 317 is OK. Nuts.

And I was an EE major. Never used a lick of it since school.

I'm learning a lot.

OK so you have 48VDC then

 

[apl]

OK so you have 48VDC then

No!!!!

I've got 8 something.

 

[scrubs]

Has anyone tried Martha Stewart's recipe for Burr Brown Chip No-Bake Cookies? I had some over the holidays and they were so warm and transparent. Heck, they're so cheap, I sprinkle them on my cereal in the morning!

 

[apl]

No!!!!

I've got 8 something.

Maybe it's because there's no current going through the 317.

 

[dayvel]

I've used both the INA2017 and the INA103. I just used the circuits in the app notes and both work just fine. The only thing to watch out for is that the "suggested" input network (47ohm resistor and 1.2uH inductor in parallel on both inputs) is more like "mandatory"; cable capacitance is enough to make these little guys very unhappy.

Also keep the wiring to the gain-setting resistance short and keep the wiring for the inputs away from the ouput. I've built these things on Rat Shak "experimenter" boards with no probs.

Don't see any obvious way to run these single-ended; these are instrumentation amps, not op amps.

 

[apl]

I've concluded that the my power supply schematic is fine but my execution of it has mistakes.

 

[mshilarious]

I've concluded that the my power supply schematic is fine but my execution of it has mistakes.

You know, a PCB is a wonderful thing

 

[apl]

You know, a PCB is a wonderful thing

I must concur. Knowing what you're doing helps a lot, too.

 

[apl]

I had accidently swapped R1 and R2. Fixed that, so now I get around 43V which is what the LM317 data sheet says I should get. I've seen a couple of circuits with the 240 and 8K2 R1 and R2, but by the math around 8K9 would get you closer to 48V.

I feel much better.