My Covid-19 project

Actually negotiating for the 500mA ?? ;D

cheers

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

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

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.

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

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

Wuhan, of course. They have the best bats.

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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Here's your Schematic that I colorized

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

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

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

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.

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!

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

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

My Bad

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

This works, I think.

Rev A

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.

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.

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?

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.