Author Topic: Solid State AVR on an ST-3 Head - Any need for it ?  (Read 873 times)

BruceM

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Re: Solid State AVR on an ST-3 Head - Any need for it ?
« Reply #15 on: May 12, 2022, 02:39:08 AM »
Thanks for the kind thoughts.
Alas, I have memory and cognitive impairment from MS and epilepsy, so technical writing is just plain misery.  Can't remember the previous paragraph so can't hold onto context, etc.  Same issue (worse) with software.  Makes technical projects very hard and stressful.

So I'm doing a whole lot less, plus seeing quacks and doctors,  trying new treatments without any success, which is hard on morale and the wallet.


Powdermonkey

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Re: Solid State AVR on an ST-3 Head - Any need for it ?
« Reply #16 on: May 14, 2022, 09:05:12 PM »
Ever look up hyperbaric treatment?

BruceM

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Re: Solid State AVR on an ST-3 Head - Any need for it ?
« Reply #17 on: May 15, 2022, 12:35:44 AM »
Yep, designed and build my own hyperbaric chamber and tried that 20 years ago. It  gave me a nasty MS flare up that lasted a few months.  About 10% with MS react very badly to hyperbaric oxygen, according to some UK research. Most find it helpful to some degree.

It was made from a 90 psi horizontal water pressure tank with an extra end cap. It had 8  1 inch by 4 inch light openings on top,  with 1/2 polycarbonate "windows" fitted inside, and dual outside or inside controls for operation.  I could sit and turn around in it.   It had an oval door which sealed via gasket with even the slightest pressure.  It was made from an extra stamped end piece I bought with the tank from an in-state manufacturer.

I sold the chamber to an MD in Texas who wanted to try it for her husband.  She was pretty thrilled to get a chamber tested to 4 atmospheres for (then) under $3.



« Last Edit: May 15, 2022, 12:39:18 AM by BruceM »

mikenash

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Re: Solid State AVR on an ST-3 Head - Any need for it ?
« Reply #18 on: June 23, 2022, 02:28:34 AM »
That may be OK, it looks like a modern one.  A picture from the other side would help.
I'd order a new one to have on hand, in case it's crap.  When your output voltage suddenly goes way low, that's the usual culpret (with Chinesium bridge diode).

Here's an example of what you want:
https://www.ebay.com/itm/224811975854?epid=25016784898&_trkparms=ispr%3D1&hash=item3457d684ae:g:LP0AAOSw07hh9D9b&amdata=enc%3AAQAGAAAA4DnkmsOqUD5Je7CXIp1vp20AWgEgoojiNCXA37jPM8BMpvjM1U4Yfupo7yaDHQ%2FWrT%2Fcg4npkrGOlp5z50wf8GCQFT68xqa89gdinHLtlG0vPIZUGluNz0ey9Ioc0pK3Egc8qiRPkpJjqCOqHKNYkftz9cvug0K4JLVudSv8c1EZzaWdRRSb8BoT9diH5euXC1Ihu0SFZuxvdHAKjrf9cCk4jDaSsDU2C8qjhiastbesKQfUKpD7COBS946hkpx6XRc%2FpBP24L9PhzmcE15wZsOrD8Tkccxa%2BJxCaq%2FUaYPc%7Ctkp%3ABFBMssOY95Vg

A bridge rectifier is just four diodes potted in a metal or plastic box.  Two AC inputs, usually opposite corners, and two DC outputs, usually marked + (plus)  and - (minus).  It turns AC (from the harmonic winding on the stator, which is very spikey and non-sine, and turns it into pulsed (spikey) DC for the rotor.  The rotor windings have a huge inductance, so they smooth the input current to create a more constant magnetic field at the 4 rotor poles. 

For this application, the metal body is better for heat sinking to some aluminum. A die cast aluminum case to replace the doghouse comes to mind. Use some thermal paste or a dab of silicone caulk It should be as thin as it can be, to just increase the surface contact area.

Hey Bruce - thanks again.  Just what I needed

See pics?

The very thing you left the email link to on EBay is available here on our TradeMe so cheap I bought two (one for a spare) and some heatsink compound.  I have some finned alloy sections off of VSDs that'll make good heat-sinks

These little fellows just have a " + " for DC positive I guess - and guess also as you say that DC neg is diagonally opposite.

They also have " AC" and I guess, again, that the other AC is diagonally opposite.  Do you think it matters which AC terminal is neutral and which is phase - or if it matters?  And how to tell which is which - if it does matter?

Cheers

BruceM

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Re: Solid State AVR on an ST-3 Head - Any need for it ?
« Reply #19 on: June 23, 2022, 02:49:37 AM »
Hey Mike,
You got it right, regarding diagonals.  It does not matter which AC terminal is neutral.
Four small  AC voltage rated, 0.1 uF capacitors, between each of the terminals, one on each side, will greatly clean up the EMI on the AC power  for very little cost. It stops much of the diode noise at starting and stopping conduction right at the source.

Here's one rated for 275VAC:
https://www.digikey.com/en/products/detail/kemet/R46KI310040H1M/5730927

I usually solder them to the quick connect tabs near the base, so the connectors still work fine.

Best Wishes,
Bruce