Line AC reduction.

My bro-in-law purchased this gizmo, originally designed for tube guitar amps, to lower his line AC from 120VAC to 110VAC because his Chinese-made EL-34 based stereo amp was running very hot. It works like a charm. Because it is designed for use on the road by gigging rockers, it is sturdy and compact. Certainly a bargain compared to a real variac!
http://www.amprx.net/about.html

I think it would be excellent for anyone wishing to preserve a vintage Dynaco designed for the old 110 VAC standard without having to switch out power tranny, or for someone with line voltage above the "ideal" 117 for the VTA products. It has a long list of famous endorsees in the rock universe.

Effin' groovy.

Looks to be adjustable as well, allowing you to reduce the line level by 4,8,12, or 16%. Be nice if it was a true variable though, as the 4% would have been too high for my 125vac and 8% too low for my liking.

Couple hundred bucks is a lot more than I paid for my lil bucker ... that's an old Hammond 6a dual winding with the 6.3v side hooked up to drop the voltage.



PS ... don't expect your power to stay steady. After I built the bucker, the power company must have fixed the problem and I haven't seen it over 120vac for a while now. That's what the new Latino's are built to see, so the bucker is stored ... for now. I still haul out the Kill-A-Watt every now and then to double check where I'm at.

Yeah, sKiZo, they keep movin' the goalposts on us. I suspect that this BrownBox unit is simply a transformer with several closely-spaced secondaries. Not particularly useful for someone who has wild fluctuations {I love that word!} in line AC. And I like your mother-bucker....
But this unit managed to reduce the temps on Kevin's EL-34s from a dangerous near red-plate 450F to a nice 325F. The circuit was probably designed for 110. Trust Not the Commie.

Cheaper than running a cable from Beijing, right?

Transformers similar to the one I used aren't exactly cheap either. Lucky me, I found this one buried in one of the "some day I might need it and I'm too lazy to throw it out" piles. Ditto on the old school metal outlet box. Those are handy, what with the built in protection and all.

Only place I screwed up was putting the output outlet in backwards. Couldn't plug in my non-latching GFCI adapter. Easy enough fix ...

Even if you ran a drop cord from Beijing you'd still need a bucker. They run on 220 VAC over there.

I'm on here all the time complaining about line voltage...to review, I live on a farm at the literal end of a rural above-ground line and I get 1) consistent 125 to 126 VAC line voltage and 2) the impact of every "event" that may occur on the line before it hits my house -- lightning strikes, downed lines, blown transformers, etc. After trashing out my Citation II twice and revamping my Dynas I finally talked a friend of mine out of one of his Variacs to use on the newly-repaired ($700 later) Citation, set at about 119 volts. I realize this will vary depending on my line voltage but it always seems to be in that high range and I figure 119 is a safe compromise...could go as low as 117 and as high as 120 maybe?

I see Variacs on Amazon etc. that go for about $100-$120 that will handle my load....I guess you have to get a little higher rating with these things depending on the pull there are some 3 or 4 amp units that are less expensive but I guess we need at least 6 and maybe 10 amps with these rigs, especially the H-K. The Brown Box looks convenient and small but it is over $300. Also something very comforting and traditional about an old, heavy wound Variac.

wildiowa wrote:I'm on here all the time complaining about line voltage...to review, I live on a farm at the literal end of a rural above-ground line and I get 1) consistent 125 to 126 VAC line voltage and 2) the impact of every "event" that may occur on the line before it hits my house -- lightning strikes, downed lines, blown transformers, etc. After trashing out my Citation II twice and revamping my Dynas I finally talked a friend of mine out of one of his Variacs to use on the newly-repaired ($700 later) Citation, set at about 119 volts. I realize this will vary depending on my line voltage but it always seems to be in that high range and I figure 119 is a safe compromise...could go as low as 117 and as high as 120 maybe?

I see Variacs on Amazon etc. that go for about $100-$120 that will handle my load....I guess you have to get a little higher rating with these things depending on the pull there are some 3 or 4 amp units that are less expensive but I guess we need at least 6 and maybe 10 amps with these rigs, especially the H-K. The Brown Box looks convenient and small but it is over $300. Also something very comforting and traditional about an old, heavy wound Variac.

Yessir, I'd more than likely opt for a Variac myself, due to its broader functionality (continuous variability, usefulness as a test-bench tool, etc.).
But there is a benefit to the BrownBox which is not obvious - it is a true transformer (discreet primary and secondaries) rather than an autoformer (primary and secondaries are the same windings). That means that there is isolation between the input and output, and should catastrophic line conditions occur, you should be protected. Also note: this is a 5 amp unit which retails for $189, not "over $300". So for some, it might be a better choice than a Variac(TM) which may or may not be designed for continuous use. I'd definitely not buy a bargain Variac - under $100. Do you smell something burning, dear?

Check your local Craigslist, I picked up a 15 amp STACO Variac, like new for $150; it lists for $750.......

Over the weekend I was explaining to a friend how over-voltage likely contributed to a couple of tube failures. This morning, he forwards me this:

You might be able to run your tube amp without issues

Date: Mon, Oct 26, 2015 at 11:48 AM
Subject: Voltage reduction planned for Tuesday

Please be aware that ISO-New England will implement a system wide Voltage Reduction Test on Tuesday 10/27/2015. This test is conducted twice a year to help determine the amount of load relief available if ISO-NE implemented a 5% voltage reduction during the summer or winter peak period. ...

The test is scheduled to take place from 10:00am to 10:30am and again from 2:00pm to 2:30pm. If system conditions prevent the test from taking place on Tuesday, the alternate date is Thursday 10/29/2015 (same times).

We don't anticipate any problems but as stated above, some equipment may alarm as it gets close to minimum acceptable levels. We will monitor voltages on the E&U system and report any anomalies to NSTAR / Eversource.

Do you suppose we could just ask the ISO and utilities to make the 5% voltage reduction permanent?

Gotta love the electric utility companies. I have a research lab at the John Burns School of Medicine where I have a -140 degree centrigrade freezer. This 3 phase 240v unit does have a voltage boost provision which is always engaged because line voltage varies between 197 and 205v within the building. I keep telling the building engineers they need to up the input voltage but that would require the local utility to replace their transformer which costs money. At home its a solid 120v.

Just pick up a Staco Variac Energy 3PN2210B Variable Control Transformer 120V-in 22A 0-140V-out for $100.00. Plus $16.00 for shipping on E-Bay.
It won't be delivered until Friday.
It was listed for $185.00 and I made the offer of $100.00 never thinking it would be accepted.

You never know, right!
Yahoooooo!

sKiZo wrote:

sKiZo, your 'lil bucker sent me off to learn about bucking circuits since my knowledge at this point is pretty basic.

Are the white and black the primary and yellow and green secondary?

Is your circuit similar to this example of a bucking regulator, albeit with different winding ratios and a switch on one leg between the AC source and the transformer?

No set color code, so you do need to do some poking around with a VOM to get it right. In this case, I used an old Hammond two winding transformer ... simple that way ... and wired the 6.3vac secondary winding in series with the 120vac primary. DO test for output after hooking it all up as you can just as easily BOOST the output by the value of the secondary if you get it backwards ...

This simplified diagram might make it a bit easier ... just substitute winding values:



You can do it with more complex multi tap transformers as well, but it gets more complicated trying to figure out which is which, especially when trying to use "found" items that don't have a good schematic available.

And ya ... the old power strip is used a lot for this as it conveniently has the little things like power switches, fusing or breaker, and such all built in. The one I used was also collecting dust for a long time before being "repurposed" as a bucker.