ST-3/5 regulator plans available

[Stan]

What a revolutionary idea!
Stan

[BruceM]

Cliff is still working on the 240V PCB version, his real work keeps him busy lately. He will be doing some prototype testing this weekend, before ordering the new PCBs.
 
Over 70 downloaded my original design documentation, 29  people have downloaded the basic AVR documentation/photo package, and a dozen have downloaded the ExpressPCB file for the 120V version.  If you do build one, both Cliff and my email addresses are in the pdf doc package. We'd love to hear from you.

Best Wishes,
Bruce

[Tom]

I'm interested in ordering a board for the 240V version.

Also can someone confirm my understanding that the "120 Volt" version is wired to produce only 120 volts out of an ST 3/5 and the "240 Volt" version will produce the standard 120/240 VAC that goes into standard house wiring?

[dpollo]

I have read this entire thread with great interest. I have recently ordered an AVR from High Tech Hicks found elsewhere on this site and will be interested to see how it works on my 5KW Kato which has a direct connected exciter. I  have other machines in operating condition and therefore am interested in other AVRs.  My hands on experience dates back to carbon pile devices and other mechanical devices that predated me by half a century but todays loads require a much more refined input.

 As I understand it,  modern machines use line voltage, reduced and rectified for excitation so loss of residual magnetism for start up is a problem. On my unit, it should be possible to use the shunt wound exciter as originally set up with a variable resistor in its field for startup then switch the exciter field to the AVR. Am I likely to damage the AVR during the switching. Should its output have a load on it when the machine is running on the manual control?  If you can provide any insight on this I would be grateful.

[BruceM]

Tom, yes, the 120 volt version is only for ST3-5's that are set up for 120VAC output only.
The new 240V version will be for ST3-ST15s set up to generate 240V (and two legs of 120V relative to the neutral).

This design (both versions)  is very gentle on the ST brushes and field coil-  since excitation with this design is normally near zero crossing time of the AC output, there is a lower voltage, longer, slower pulse width than in some pulsed designs. I think this should help with brush and slip ring longevity.  The rotor/field coil only sees higher voltages for surge loads.

Some AVR designs bang very high voltage for a very short pulse- often at the AC waveform peak.  This can cause notching of the AC waveform, a lot more EMI, and I suspect slip ring and brush wear.  I'm basing this on some good data sent to be by Bill Rogers on a unit he tested.  These really aren't designed for our ST type heads...they are for brushless designs.  I don't know anything about the import one being offered...or whether it's really designed for the ST heads. 

Bruce M

[Tom]

Sounds great, thanks for all the hard work! I'm anxiously awaiting the 240V design.

[mike90045]

What does the  ST stand for  ?

[t19]

Simple Technology :p

[BruceM]

You're most welcome, Tom. 
Bruce

[matt]

Hi Bruce,

Any news on the 240 volt version of the AVR?
Will it be able to regulate ok at 50Hz??

Matt

[MacGyver]

Well, the flicker from my 6/1-ST combo is awful...
I mean REALLY annoying, even with CFL's (and worse with incandescent)

I suppose it's time for me to build an AVR.

Has anyone else built one of these since this thread was last posted to? Does this circuit do an OK job of killing the flicker?

[BruceM]

I have not received any responses from any of the over 50 folks who downloaded the schematic and board layout files.  But yes,  the flicker reduction is very noticeable.   I have abandoned plans to work on the 240V version.  My plans for my original prototype 240V version (which has been in service for over a year) were posted, but there is no PCB. 

Perhaps one of the AVR's being sold by High Tech Hicks would suffice for your needs.

Bruce M

[MacGyver]

Thanks Bruce.
I probably won't buy an AVR from anyone. It's the sort of thing that I prefer to build myself so I can easily fix it and/or keep extras in stock just in case. I'm not sure yet if I'll design my own or use an existing design like yours.

Are there any significant design changes in the 240V version or is it mostly a variation on the same circuit?

Hey, watch the Gate-Emitter voltage on those IGBT's.!
The one spec'd in your parts list has a maximum continuous Gate-Emitter voltage rating of 10V and a minimum rated breakdown voltage of 12V.
It looks like that one gets a full 12 volts when the output of that TS921 goes high...

[BruceM]

Glad you caught that,  MacGyver.  My prototype uses a bipolar Darlington power transistor with intentionally slowed down on/off times (100+usec) for lower EMI, I didn't spend enough time looking at the IGBT selection.  Plenty of other choices (250V Mosfets), IGBT's like FGPF90N30 with a 15 volt gate to emitter rating or the operating voltage could be lowered to 10 volts by replacing the 7812.

[12 gauge]

I would like to build this regulator, and it seems there may be a problem here, so should I change to a 7810 regulator, or change the IGBT to a FGPF90N30 that is mentioned?

This is my first post but I have been lurking for a couple years.  This forum is great and I've gotten many good ideas for my Listeroid.  Thanks to all.