Cheap DIY balanced power device

[Ten 99]

Since this is an opportunity for me to learn a thing or three...

What function do the capacitors (running between hot and neutral) serve that are wired onto the backs of the 120V receptacles?

Also, what is that "soft start" device that you referred to? How does that function?

By the way, thank you for another fun learning adventure. This is by far one of my favorite places to visit now! :B

[ThomasW]

Hi,

Glad you're enjoying the project...... :T

There are 2 more versions of this design to follow.

The next design will have one more receptacle, and additional power line filtering.

The final design will be an 'expandable' model able to hold 2 transformers. Initially it can be built with a single transformer. Later a second transformer can bolt into the same chassis. Doing that will double the unit's capacity to 1.6KVA. This unit will be built in a 17"X10"X3" chassis, that will fit nicely in a equipment rack.

Now to answer your questions............

1)The caps serve as differential noise filters.

2)The soft-start device is a NTC resistor (Negative
Temperature Coefficient Resistor). When 'cold' little current flows through it. When the transformer is plugged in the resistor begins to heat up. As it heats up, the resistor allows more and more current to flow into the transformer. It's function is to prevent the in-rush current to the transformer from tripping a circuit breaker, or blowing a fuse.

The unit is now completed and 'burning-in". As usual Broadband users can click HERE to see the final stages of assembly.

For those with dial-up, here are pictures of the final assembly.

Pic #15



Pic #16



Pic #17



Pic #18



Pic #19



Here's Pic#19 the competed unit. I'll shorten the power cord later after deciding on an appropriate length. Suggestions?

One observation and comment. In a previous thread we were ask about using the Avel Lindberg transformers. We replied that there was information around that the transformers were noisely. Well not true. This transformer is much quieter than my very expensive B-P-T BP-2.5

[ThomasW]

I forgot to add the usual disclaimers associated with projects like this.

This unit is not UL or CE rated. There are no warranties either expressed or implied with this product. Use this product at your own risk.

We (myself, Jon, HT-Guide, or any of the mfgers of the components used in this product) are not responsible or liable for any occurances should someone decide to build and use their own, or someone elses version of this unit. This includes but is not limited to; flood, fire, explosion, earthquake, WWIII, terrorist attack, baldness, impotence, alzheimers, divorce, children running away from home, wife running away from home, children using drugs or alcohol, wife using drugs or alcohol, or anyother bad thing that can, does, or could potentially occur in anyones life at anytime.

Enjoy the benefits of balanced power ........ :T

Regards
Thomas

[DeanP]

Would this Toroidal transformer work from Partsconnexion ? Its a Hammond. Here is the link HAMMOND 182Q60 750 120V ct @ 6.25A 60V @ 12.5A 6.40 3.10 13.53 $86.40

[ThomasW]

A search of the Hammond site came up with This Hammond catalog Page it contains several transformers with 120v primary and dual 60volt secondaries.

Yes the unit you posted will work. But it's smaller (750va vs 800va) and costs more ($86.40 vs $69.93) than the Avel Lindberg unit from PE. Not sure how shipping and duty will impact the total costs. All these transformers are heavy, the one is the "Cheapskate" design weighs 13+ lbs...

[David Meek]

This is such a great thread! Thanks Thomas - you poobah, you. ;x(

I can't wait to see the big unit. :drool: (any reference to Randy Johnson is purely coincidental)

[ThomasW]

I can't wait to see the big unit.

It will look a lot like the little one only bigger..... :wink:

I should add that none of these DIY units incorporate surge protection. They can of course be plugged into a surge protection unit. Or surge protection can be plugged into the balanced power unit.

I did a quick A/B comparison of "The Cheapskate", against one of my high-end balanced power units that currently retails for $800.

I used my 32" Toshiba CRT tuned to our local news channel that's live broadcasting the news in HD converted to NTSC. This is a very clean signal to begin with. Both units improved the picture. Less video noise and deeper, richer colors. There was no obvious winner in this initial comparison. When time permitts I'll grab a DVD and do a more extensive testing. I don't anticipate there to be significant differences given the nature of these devices.

I should add that the for tests being performed I'm using a 20 amp dedicated that has the Tice Titan/PowerBlock II (dual 66lb) isolation transformers on it. So even with all this prior power conditioning, the balanced power units are improving the image quality.

[David Meek]

There was no obvious winner in this initial comparison.

Hmmm, $99 vs $800 for a similar level of performance? Oh, I think there's a winner, all right.

[ThomasW]

Ok back to work........

Started a new webpage detailing the construction of the next larger box. This version is using the same 800va transformer, and same basic construction, but in the larger 10"X10"X4" junction box. This device has one additional AC receptacle and a IEC input connector containing RFI/EMI filtration. As with it's smaller brother all the receptacles will be isolated with individual 8 amp RFI/EMI filters

Pic #1
Pic #2
Pic #3

[David Meek]

Thomas, is there any wiggle at all with the snap-in IEC plug? Also (WARNING: newbie questions), if the fuse is a "slow blow", is there a "fast blow"? And what would be the benefits of each?

[ThomasW]

David,

The springs on the IEC connector are made from stainless steel. As long as the cutout is the right size no there's no wiggle. Schurter of course makes versions fo this same connector that have 'ears' for attaching it to the chassis with machine screws.

Since the steel in these junction boxes is much thicker than the metal in a standard rackmount chassis, I'm trying to limit the amount of metal work.

The fuses do as their names imply, fast-blow pop the instant demand is higher than the rating of the fuse. Slow-Blow provide a slight delay before popping. If one is protecting delicate internal components, then fast-blow is the way to go. Here we're basically just looking to protect the transformer so slow-blow are fine.

I grabbed the Equi=Tech balanced power FAQ I'll put a link to it in the DIY article as well. It pretty much covers the basics of balanced power.

[ThomasW]

Next task is to add in the 3 RFI/EMI filters. These provide a nice level of isolation between the outlets.

Note to the budget builders. The RFI/EMI filters cost about $8-10ea with delivery. These can be added to the project at anytime. So if they don't fit into your budget now, add them later. That's why I show them mounted to the lid. It's not necessary to gut the unit to add in the filters, if they're mounted to the lid.

Some may look at the wire being used and think it's too small for the loads. The wire is 16 gauge mil spec. This means it's silver plated copper with a Telfon dialectric. The runs inside the box are quite short. So this size wire is fine.

Pic #4

[RonS]

Would this Toroidal transformer work from Partsconnexion ? Its a Hammond. Here is the link HAMMOND 182Q60 750 120V ct @ 6.25A 60V @ 12.5A 6.40 3.10 13.53 $86.40

You should check out Plitron, they have 2 transformers that seem suitable, 750VA #107052201, $120.64CDN, 1000VA $117052201, $139.73. They're located in Toronto, make excellent products, Mark Levinson uses them for their amplifier transformers. Both have dual 60V secondaries, with multiple primaries.

[ThomasW]

Okay this one's done too. Here's the broadband LINK and links to individual pictures.

Pic #5
Pic #6
Pic #7
Pic #8
Pic #9
Pic #10
Pic #11
Pic #12

If anyone decides to make one of these I suggest using the 10"X10"X4" box. It's much easier to work with given it's larger size.

[David Meek]

Looking at my equipment closet brings up a question. Would it be harmful in any way to set this unit on its side? Ie, so that the transformer is sitting in an upright position (like a car's tire). I'm thinking it'd be okay, but just to be safe. . . .

[ThomasW]

David,

As far as I know that shouldn't be a problem.

The only possible situation I can think of is that possibly over a long period of time the transformer core could warp. It's a heavy (13lbs) donut (hollow center) and is held in place only by friction from the big washer attached by a single bolt. One doesn't torque down on a torroidal transformer because that can damage the integrity of the unit. (I'll try to get Jon to address this before he leaves for Singapore)

I updated the entire article starting with page 1. Now it contains not only all the info posted in this thread but all the little details about the construction. This includes part numbers and links to where those parts can be obtained.

BTW don't freakout about the big red warning at the top of the page. That's for people that find the article via a web search and haven't seen all the stuff that's been posted in this thread. I'll remove it in a week or so.

Also, I do plan on having the smaller unit available for people to audtion. After a week or so of burn-in, I'll start a sign-up list for,

DIY Balanced Power World Tour, 2004" :B .

We'll start off by sending it to Texas, since you guys have had the most interest. A little word of warning, it weighs about 20 lbs unboxed, so shipping it around won't be cheap.

[Hank]

TGIF!!! arty: :beer:
I survived another week! Unbelievable - I was packaged with ribbon and a big bow and so far they think I'm doing great - but it's just a plot to drive me right over the Cuckoo's nest. BTW, the division I was given is...okay a hint...those twist-on and crimp-on wire connectors...

Poobah Thomas: an excellent, well-documented (text and photography) DIY project! Kudos to you. I'm sure you have sized the NTC properly, but it looks fairly small - I've seen that size in TV power supplies, which obviously don't handle anywhere near the current you baby does. Plug that into a Brick Wall surgemeister and you're in business.
This is a VERY cost effective project that should enable folks to build one for their hi-fi components and another for their display device.

[ThomasW]

Hi Hank,

Thanks, and congratulations to you .... :T

I too had some concern; not about the resistor itself, but the gauge of it's wire, hence my use of the very short leads. It's the same size NTC resistor used in the Transcendent unit (1000VA). That transformer is 25% larger than the 800VA unit being used here, so it should be fine.

David M,

I just had a thought. The larger torroidal transformers have the center of the transformer 'donut' filled with what's called potting compound, it's molded around a rigid plastic collar. I know we can duplicate that. Doing so would create support for the entire transformer. As a result vertical mounting should be fine.

[JonMarsh]

Sounds like you've had a week.... I know the feeling, seems like every other thing I picked up at work was broke in some way that I had to fix... literally. My tech put the wrong controller IC in the PFC proto board he built before going in for his surgery... I think he was a little pre-occupied, plus 63 year old eyes don't see as clearly anymore. Well, I rebuilt that puppy myself yesterday afternoon and this AM.

But must of my to-do's are checked off, or within sight of being there.

Now, just laundry and packing tomorrow, plus some evaluations of differences in the component output of two different DVD players, one which seems to cause problems with my transcoder in the NEC XM29+ - this is an unreleased Skyworth with component upscaling and scaling to VGA, SVGA, XGA, and SXGA RGBHV outputs.

Then, off to Singapore Sunday.

Just so you'se guys don't feel too sorry for me, this is where I'm staying the first four days I'm there...



I gotta find time to get a life....


Hang in there, Hank.

~Jon

[ThomasW]

Hey, that's a nice place, just don't drink the water ....... :roflmao:

[Glen B]

:T Nice looking job.

[Hank]

Half the weekend is over :cry:
Jon, enjoy the hotel, at least. My SCUBA diving buds from Sunnyvale and Dallas are coming for a weekend around August 7 and Jim (from CA) will be pressuring me for a stress-relieving dive trip to the Caribbean and even though I shouldn't do it on economic grounds, I think my sanity may require it. I just narrowly escaped a trip to Taiwan. Not that I wouldn't have enjoyed meeting my Taiwanese collegues, who are top-nothch, I just don't enjoy business trips like I used to. Sigh...

[David Meek]

Hank, can you afford (emotional capital-wise) NOT to take that dive trip? Definitely, congratulations on the new job, but remember to take care of Hank too.

Jon, you poor thing. Shunted off in a low-class hotel like that. Shameful, just shameful. :W Do enjoy the "scenery" (bikinis, etc.) if you get the chance.

Thomas, thats' good news about orientation of the transformer. My plan is to take the design of the larger version you've mentioned and build a similar one that'll accomodate 5 components - DVD, CD transport, DAC, turntable and phono-stage. I haven't totalled up the power requirements, but I'm thinking this'll require a standard component-size 17-inch-wide chassis. If I can find another shelf for my equipment rack (Lovan Classic II) which is out of production, I'll be able to set the BPU horizontally like any other component, but if not, I'll have to wall mount it.

[ThomasW]

David,

I'm in the very early stages of the component layout for "The Big Unit".
It will utilize the 17" X 10" X 3" Hammond 1441-32 Heavy Duty chassis from PE People should note that the top to this chassis is sold separately



There's enough room in this chassis for 2 of the 800VA transformers. If one pays attention when building it with one transformer, adding a second transformer at a later date won't be a big deal.

The only 'problem' with this chassis is it's short height. If 'standard' dual or single receptacles are used (horizontal mounting only) that limits the number of completely isolated outlets.

So I'm looking at using individual 'snap-in' AC receptacles for my version. Although there's a lot more metal working involved, one could put 8 or more individually isolated outlets in the chassis.



Finally there's enough room on the front of the chassis to mount a individual power switch for each transformer. There are some cool looking lighted switches that would serve a dual purpose.

[David Meek]

Now that's sexy! :yesnod:

[ThomasW]

As you know the "Cheapskate" versions were minimalist by design.

So unlike those designs, this one's going to have some bells and whistles. It won't be all that expensive. Probably $300-$350, for a unit with 2 transformers (1600VA total), 8 individually RFI/EMI filtered outlets, RFI/EMI input filter, individual illuminated power switches, and 6 rubber feet ........ :wink:

[David Meek]

That sounds perfect!

[ThomasW]

I ran the numbers from the actual invoices (some just arrived with my VISA bill) and my $99 guesstimate was a too optimistic. Here's a retail price breakdown.

*Transformer with shipping $77.20
Box $13
Outlets $5.00
Caps $2.50/2
Power cord $5.00
*Fuse Holder $.75
Fuse $.25
*Feet $2.60/4
NTC resistor $2.17
Schuter filters $20.00/pr
___________
Total $123.47

So as they say oops, my bad ......... ops:

Fortunately my guesstimate for the "The Cheapskate Plus" was spot on .... :T

"The Cheapskate" unit can be stripped down with little change in performance. Drop the NTC resistor, the Schuter filters, and we're down to $105 with shipping.

Now if people that live in the same geographic area (no split shipping) would order 4 transformers, we could create area based mini group-buys. Doing that would drop ~$10 off the price of each transformer

There are no beneficial group discounts available for the NTC resistors or the Schurter filters from Mouser. Buying the filters in lots of 10 drops the price by $1.00ea. Anyone can due this.

[Cowanrg]

thomas,

i found on allelectronic's site that they had 10amp filters for $2. they are corcom, so maybe a little bit less quality, and they are inlet style. BUT, you could solder directly to the pins, and even add disconnects if you wanted. with a little modifying, you can save a few bucks.

[ThomasW]

Robert that's a very nice price for a 10 amp IEC connector and filter. From Mouser those are $12ea with Fast-On connectors.

AllElectronics also has cheap ferrite beads if anyone wants to add one of those as additional very inexpensive filter.

[Cowanrg]

those ferrites are nice. im going to add one to my power cords, the surplus place by me has a good selection and about a buck or so a piece...

i should have the power cords done in a week or so. i ordered most of the parts already. i got the subs the other day, so they are running with stock power cords, ew. i gotta fix that.

[ThomasW]

The clamp on cores are not as effective and the solid units.

With the solid cores the wire/wires go through the core once and are looped around the outside and sent back through back through core center again. A full 360 degree loop is considerably more effective than a simple clamp-on. That however is a real pain to do with a thick power cord. It is relatively easy to do inside the chassis where one is simply dealing with the individual wires.

Unfortunately over time the solid ferrite cores with the 360 degree loops can themselves become magnetized and are then less effective.

[Cowanrg]

hum...

well, inside the interface box for my powercords, i could put a ferrite core on the individual wires and loop them trhough... if this is the case, how long are we talking before they become too magnetized? if its a few years, ok, thats fine.

[ThomasW]

You can run all the leads though one bigger core.

Yeap as I understand it, years it is........ so not a problem for DIY'ers

[Cowanrg]

well, my power cords are using a 10ga wire. it would be a pretty big core to run all of them through a single core at once. three smaller cores would be better. i got a little box for the guts and it isnt tall enough to hold a core of that diameter, but three small ones would work. ill give it a go i guess!

oh, and about cap size for the "bypass cap" (i guess you could call it that), the lower the uf value, the better? ive seen caps in the 0.001uf range or so, should i stick around 0.1 or 1uf? the others just seem too low to make a difference.

[ThomasW]

It's not really bypassing anything. I imagine, like the caps put across the outlets, it's a differential filter noise cap.

I didn't ask Jon how small the cap could be. He just said bigger isn't better, no larger than 1.0 mdf. When I said I've got some 0.22mfd 1200V, he said 'perfect'!

[ThomasW]

Okay, some of the parts came in and I've started the construction of "The Big Unit".

Broadband link is HERE

Individual picture links are below

Pic #1
Pic #2
Pic #3

[Cowanrg]

im curious how you are cutting the holes for the outlets in the box?

[ThomasW]

For the AC outlets I primarily used a jigsaw with Bosch metal cutting blade (old world craftmanship ... LOL ) Augmented where needed by a RotoZip tool with a little diamond impregnated wheel. I cut the opening undersized and open it with a very fine metal file.

The little diamond wheels are sold by Harbor Freight (cheap). They're designed for a Dremel. I tend to destroy the Dremel tools, so I use a Rotozip instead.

If I was planning on making more of these (which I'm not) I'd step up to the plate and buy a GreenLee punch...:wink:

[Cowanrg]

yeah, i make IEC connections with a drill press, then a jigsaw, but im not all that great at it yet.

i have a dremel tool you might like, its the dewalt version. i dont use it much because it shreds normal bits, i have yet to find bits that can take its abuse. maybe ill try the diamond wheels.

[Cowanrg]

Thomas,

as for the filter cap, i got a couple that are rated at DC volts, not AC volts... will these work just the same? for poly caps i didnt think there was a difference.

[ThomasW]

The GE metalized poly film caps I use have a 1200VDC and 500VAC rating. So yeap there's a difference in the ratings.

[Cowanrg]

ah ok. mine are 2000vdc, so they will be good enough.

[brucek]

ok. mine are 2000vdc, so they will be good enough

Be careful cowanrg, the capacitor that is across hot to neutral is considered differential-mode filtering and requires that you use a safety capacitor of the X type.

This type of capacitor (X&Y interference suppression) is designed to be used in AC line applications and has a high 'AC' rating and is required to 'short on failure' and trip your breaker and thus not result in any chance of electrical shock. You should familiarize yourself with these electrical safety issues before putting any old capacitor into use on an AC line.

Generally, basic capacitor line filtering in addition to the EMI ladder consists of a pair of Y caps (designed to open on failure) from hot to ground and neutral to ground to eliminate any common-mode noise and an X cap between hot and neutral. These safety capacitors perform and comply with safety standards. You shouldn't just throw any capacitor across the line. Safety caps are further subdivided into classes 1,2,3 for their different capabilities with respect to impulses. The X1, Y1 would be the highest rating and the largest physical size. Usually X2, Y2 are used for the application here.

The capacitance value isn't actually that important, but there's a limit. Since a capacitors reactance lowers with frequency and capacitance size, you can easily ballpark the value. The limiting factor would be leakage current at the line frequency, so don't use anything above 1uF. You want high frequency pulses and noise to see a low impedance path through the capacitor instead of passing to your equipment. The same goes for the common mode Y caps if used. The common mode capacitors will pass a small current (as a result of 60Hz reactance) to ground that needs to be limited to safety standards.

brucek

[ThomasW]

brucek,

Thanks, that's a good safety warning......

A week or more ago, that info was posted on my website in the 'parts list' section for each of the various balanced power projects.

There are issues with the cost of the safety caps, and with their sonics. As a result most are chosing to use standard film caps; then replace them should they 'fuse' (short), in the unlikely event of the transformer passing a high voltage transient.

Robert has been in email contact with me so he understands the implications of his decision