My Covid-19 project

I posted my RIS-787 schematic recently in the thread, "Abiding by the USB 100mA, 500mA rule" and reader Rick C caught an interesting, subtle potential error. But I doubt many people were aware or took a look. Here's the folder. FYI.

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 Thanks, 
    - Win
Reply to
Winfield Hill
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Actually negotiating for the 500mA ?? ;D

cheers

Reply to
Martin Riddle

The processor will enumerate, if it's allowed, but I dropped the following-the-rules goal.

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 Thanks, 
    - Win
Reply to
Winfield Hill

I've updated the files, PCB now on order.

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 Thanks, 
    - Win
Reply to
Winfield Hill

After multiple fits and re-starts, the PCB and automated assembly are finally properly underway. Next: permission for lab access for our three- member team of three, to test and apply results.

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 Thanks, 
    - Win
Reply to
Winfield Hill

"Bat charger"... uh oh. From where do you source your bats?

Reply to
Rich S

Rich S wrote in news: snipped-for-privacy@googlegroups.com:

Wuhan, of course. They have the best bats.

Reply to
DecadentLinuxUserNumeroUno

Can we get a trial going Toronto? I know several Dr's. If I was allowed to shadow you catch up. Not busy and my design day's in the '70's was inventing a SCADA subsystem for Pickering CANDU's and Black Brandts.

Nice schematic. It's the way I everything on one Size A. Some inconsistencies for power ground and analog ground and missing REFDES.

I just started looking at this forum and thread this afternoon. Here's my chromatic schematic for others who wish to follow.

D.A. Tony Stewart EE75

Retired Standard Time, since freedom-55 Richmond Hill, On

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Reply to
Anthony Stewart

Here's your Schematic that I colorized

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on my dropbox.

I hope others will be able to follow more and offer feedback. Would love to see the paper napkin design specs.

Reply to
Anthony Stewart

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on my dropbox.

Whoa, so colorful. Easier to navigate the crowded page.

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 Thanks, 
    - Win
Reply to
Winfield Hill

crowded? what are you talking about, I see several pixels that isn't used

Reply to
Lasse Langwadt Christensen

I added a few pixels of my own near the Bat Charger

, but I don't think this valve driver is ready to work as expected. Logic diagram errs.

Reply to
Anthony Stewart

If some is good and more is better, too much is just enough!

Some of the color can be helpful, like the yellow inside components. A ver y few components might want special highlighting like the battery, buttons, LEDs, connectors, etc., but highlighting all that text and such is far too much!

When I want to identify fields to be entered in a spread sheet I use the fa intest color of yellow or blue or blue/gray I can find. You want just enou gh to make them easy to find, but not so much color that it grabs your atte ntion when you aren't looking for it.

Color is a powerful tool. It can be used for good or evil.

The 70's were a strange time for color. We combined yellow and brown far t oo much and odd appliance colors became very popular. We will take strong measures to assure that never happens again!

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  Rick C. 

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Reply to
Ricketty C

We will take strong measures to assure that never happens again!

It was a 10 second tweak on Irfanview to reduce Saturation.

My Bad

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Reply to
Anthony Stewart

Does anyone else see problems with the Valve Driver, or just me?

This works, I think.

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Reply to
Anthony Stewart

Rev A

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This is just a SWAG. but Win's driver need to be revised.

Reply to
Anthony Stewart

Sorry, but your model schematic doesn't match my schematic. I think mine will work fine. It's meant to deliver high currents, to 750mA, with a relatively large output capacitor for low-Z, to handle rapid load changes, and it has the ability to quickly change the output voltage, in a few us. I won't go into the reasons that was necessary.

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 Thanks, 
    - Win
Reply to
Winfield Hill

Thanks. I had to guess on coil impedance and the PWM signal which was low and made intentional changes as the PNP doesn't do much without that data.

I'd be concerned your 0.47uF ceramic snubber Cap with maybe 1A rms ripple current will have a shorter life than COVID patients over 90.

The biggest problem I see is you are using feedback to control the valve coil voltage rather than current which is the linear measure of valve fluid force.

Reply to
Anthony Stewart

Yes. it may experience high ripple current, but despite showing an 0805 on the schematic, the PCB actually has a combo 1210+0805 footprint. Unsure of the best value for C8, I've purchased sets of 1206 1210 parts to try.

The muRata GRN21 0805 caps have 10mR DCR, and show a possible 8C rise for 0.5A rms ripple (ours will be less), but GRM31 / 32 parts show a negligible rise.

The valves share one Vv voltage, but individual power levels are set by PWM, via Rx to each TPL7407 switch.

I enjoyed watching your dynamic modeling video, even if it was running the wrong model, with wrong answers. It'd be interesting to see it with a fixed schematic. How did you make that video, exactly?

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 Thanks, 
    - Win
Reply to
Winfield Hill

Using IrfanView to colorize the schematic caused it to lose its searchable text capability (find designators), and Acrobat's OCR wasn't able to bring that back.

It's too bad Altium's schematic capture doesn't let a user color-annotate drawings. Annotating externally means every time you make a little change and update the pdf file, you'll lose any previous annotation.

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 Thanks, 
    - Win
Reply to
Winfield Hill

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