Cheap DIY balanced power device

**JonMarsh** · 24 June 2004, 10:30 Thursday

Though we have our esoteric tastes in many areas, Thomas is once again proving we can bottom feed with the best of them... :E :T :B

I'm probably going to build a couple of these with just a few tweaks for some of my own gear, but due to my SAF issues (self acceptance factor, not spousal acceptance factor) I'll probably splurge on some Par Metal cases. But that doesn't invalidate the concept.

For a smaller stereo reciever, 800VA might be just fine. I'm going to check and see what the consumption is on my NEC 9PG+ projector, too; this could be ideal for giving it some isolation.

Us social hermits love isolation units!

~Jon

**ThomasW** · 24 June 2004, 13:00 Thursday

Ok let's get started. First we'll create the hole in the box for our outlet/outlets.

I'll post individual links to each pic for those with dial-up. If you have a high-speed line just click HERE to see all the pics

Pic 1 Remove the knockouts except for the last ring.

Pic 2 Remove the outer "ears" from the AC receptacles. I put the receptacle in a padded vise and use a hacksaw.

Pic 3 Orient the receptacle over the hole and mark the position for the mounting screws.

Pic 4 Drill the holes for the mounting screws

Pic 5 Test mount the receptacle. Note that it must be removed to put on the wires.

**Andrew Pratt** · 24 June 2004, 16:53 Thursday

This is one that even Andrew can afford, and that he can build ...........

Thanks....I think

**ThomasW** · 24 June 2004, 18:59 Thursday

Just goofing on you Andrew...... :B

The 'basic' version of this unit will come in less than $99US ...... :T

I'm also creating a slightly more 'upscale' version with some line filtration that will be a bit under $150US.

They both use the same tranformer, the more expensive one just has more bells and whistles....

**Ten 99** · 24 June 2004, 20:16 Thursday

Shweeet!

I love you guys.

:B

It'd be cool if you had the basic "plan" and then maybe some "a la carte" extras that could be figured in depending on the person's budget and what benefit they thought they might get. Perhaps that's the plan already... I suppose I should just shuddup already and let you finish. :W

How would a person go about figuring out the size of the transformer needed? My assumption is that it would be based on the total demand of the wattage for the devices hooked up to it - and here the my guess is that it's based on max watts demand, not average. If I'm wrong here, please school me.

:T

**JonMarsh** · 24 June 2004, 20:59 Thursday

Well, there's watts and then there's watts...

The problem is that a LOT of equipment that we use in our AV has this problem called poor power factor- in laymen's terms what that means is that the current waveshape is moderately distorted compared with the incoming AC voltage- this places extra stress on stuff like transformers, for example- including balancing transformers. How much? Well, if you're making a normal rectifier capacitor input power supply for an audio amplifier (which is what 95%+ of the audio amps out there use), the power factor is typically 0.65 or less. In fact, because of the various loss effects, it's normal to talk about transformer utilization factors for different applications, and for an audio power amp power supply, you normally consider transformer utilzation factor to be about 0.5. That's why amplifiers like a Dynaco Stereo 400 had a 1 kVA transformer...

Now, there's two key factors in transformers- temperature rise, and regulation. You don't want to exceed the average maximum power rating of the transformer continuously because of temperature rise and eventual damage. But in real life, this is rarely a problem. What is a problem is regulation- VA ratings are typically based on some specific regulation factor- ie., 800VA output (resistive load) with no-load to full load regulation of X%. X may be 3%, 5%, or even higher.

Now, you could put an 800VA balanced power transformer inline with a receiver with a maximum power draw of 800W, but the voltage regulation loss of the balanced transformer would be in series with that of the reciever. And because of this power factor issue, the peak current (and peak loss) is even higher because of good old Ohms law- the power loss is I^2 X R, so when current goes up due to peak draw only at the top of the waveshape, the loss rises at a faster ratio than the output power.

So, if you want regulation to stay tight, I would suggest a 2:1 ratio for most audio gear re VA rating as a starting point. For one 800VA unit, think an amp or combination of front end gear that doesn draw over 400-500W total. You can go higher, but keep in mind that there may be more power supply drop than usual at peak output.

In other words, don't put one of these on your 1 kW sub woofer amp!

~Jon

**ThomasW** · 24 June 2004, 21:04 Thursday

Below is a link to an java calculator designed to calculate loads for a computer UPS (this is fine for our purposes). Just enter the watts or amperage pulled by each device then hit the calculate button and read the result in the "Minimum UPS Capability".

http://66.102.7.104/search?q=cache:XaDIKx374XwJ:www.csgnetwork.com/upssizecalc.html+online+calculator+for+UPS+load+factors&hl=en

Then follow the guidelines Jon provided.

And yes we'll describe the benefits of the various upgrades.

Edited to fix link.

**Al Garay** · 25 June 2004, 01:41 Friday

Sorry for the beginner question but what about plugging a light bulb into this?

I could see someone in my family accidentaly plugging the Stiffel floor lamps into this BPS and causing great grief as my wife sees her beloved lamps explode. I can imagine having to explain what happened to Costco the week after returning the widescreen tv because of power failure.

Al

**JonMarsh** · 25 June 2004, 10:55 Friday

Al, why do you think a halogen lamp would explode or a TV fail?

Please explain your reasoning.

Best regards,

Jon

**ThomasW** · 25 June 2004, 11:27 Friday

I don't remember where I read it, but years ago I recall reading info about not plugging regular light bulbs into balanced power circuits.

As a result I thought is was prudent to put a caveat in my introductory post in this thread.

I'll try to find the source of that info and post it.

There's certainly no problems with having a any kind of TV or projector plugged into a balanced power unit. I've had my TVs and projectors plugged into them for years.

**Al Garay** · 25 June 2004, 13:51 Friday

Jon,

Like Thomas said, I was referring to his remark about:

And NEVER plug a plain light bulb into it.

I have read of others having no trouble plugging their TVs into balanced power supplies. I was wondering why you were singling out light bulbs.

Thanks,

Al

**ThomasW** · 25 June 2004, 14:50 Friday

I started work on the upgraded box too. It makes sense to build them both at the same time. That means only getting the needed tools out once. This LINK goes to the entire webpage.

Here are links to Pic #6 and Pic #7

Next, in go the power cords.......

For those that haven't figured out why this is progressing so slowly; I'm killing time waiting for PE to deliver the transformers. That won't happen until next Tue or Wed.

**JonMarsh** · 25 June 2004, 14:51 Friday

Well, a plain light bulb should be no problem at all, becuase they're just variable resistive loads; relatively low resistance (high inrush) at turn-on, but settling down in milliseconds to a pretty resistive load.

Some lamps like Halogens with dimmers might have weird waveforms if they use an SCR, and may actually only conduct in one direction. They SHOULD use a triac and conduct in both directions. A lamp which has an SCR could be a bit of a problem, due to current flow in only one direction, but becuase the transoformer has the volt-sec opportunity to reset, it will probably just cause it to hum. High power halogen lamps might not be a good idea for that reason.

Another reason to use a clamped DC filter as I plan...

But since we're putting the A/V gear on a balanced circuit to isolate it from neutral grounds, why plug lighting into it, anyway?

I know, stuff happens....

~Jon

**brucek** · 25 June 2004, 18:44 Friday

Sorry for the beginner question but what about plugging a light bulb into this?

AL Garay,

Plugging a lamp into a balanced power unit is quite dangerous.

Standard residential differential power from the wall consists of a +120 volt lead and a neutral lead. The neutral lead is bonded to ground in the loadcenter of your house.

The AC plug on a standard lamp is keyed so when it's plugged into the wall it ensures the base of the bulb is connected to neutral and the pointy business end of the bulb gets the +120 volts.

When you or your family is messing around changing a burnt bulb, they have no way of knowing that the lamp may still be turned on. As they unscrew the burnt bulb, it is highly likely their hand comes in contact with the metal base of the bulb itself. Luckily it is connected to neutral.

Guess what happens if it was plugged into a balanced power unit. The base of the bulb will be at 60 volts.....

brucek

**ThomasW** · 25 June 2004, 19:05 Friday

Okay that's settled, don't plug your lights into a balanced power transformer.... :W

**Al Garay** · 25 June 2004, 21:43 Friday

Thanks Bruce.

**Hank** · 25 June 2004, 22:22 Friday

Thomas wins the "Most Obvious Reply" award, a magnesium driver cone shaped lapel pin! :B

**JonMarsh** · 28 June 2004, 12:55 Monday

Originally posted by brucek

AL Garay,

When you or your family is messing around changing a burnt bulb, they have no way of knowing that the lamp may still be turned on. As they unscrew the burnt bulb, it is highly likely their hand comes in contact with the metal base of the bulb itself. Luckily it is connected to neutral.

Guess what happens if it was plugged into a balanced power unit. The base of the bulb will be at 60 volts.....

brucek

Aso desu; arigato gazai mashta.

You know, I have virtually NO conventional incandescent bulbs in my home, and no floor or desk lamps using them, so I forgot about this safety issue. I was only thinking in terms of the electrical issues. And I always unplug ALL lamps before changing bulbs/tubes. But much of the world probably doesn't.

Still, it wouldn't hurt for us to put a puch tape label on our DIY power units to not use lighting or change bulbs on lighting connected to the output without unplugging.

~Jon

**JonMarsh** · 28 June 2004, 17:04 Monday

Do NOT use balanced power with NEC CRT Projectors!!!

In my continual quest to gather as much relevent and irrelevant knowledge as possible regarding NEC CRT projectors (what with me being a new owner and all) I have come across the interesting information that there's something unusual about how their power supplies (internal) are configurated, and having even small amounts of AC relative to safety ground (such as 3-3.5V RMS) can throw things like sync behavior quite out of wack.

I repeat, Do NOT use PG, PG Extra, or XG series projectors in a balanced power arrangement!!

What is recommended it to use dedicated AC, and especially to keep light dimmers out of the mix, because when they get faulty they can cause current/voltage injection into the neutral.

This concludes today's public servicemessage.

**ThomasW** · 28 June 2004, 17:33 Monday

Bummer..................

**Dennis H** · 28 June 2004, 20:36 Monday

Speaking of PJs, especially the digital ones with very hot bulbs, some people recommend running them off a UPS. The deal is the fan keeps running for a bit after a normal shutdown to cool the bulb in a controlled fashion but just cutting the power and then maybe restoring it while the bulb's still hot can be a Bad Thing. I don't know about CRT PJs but some of them have pretty big fans so the same thing might apply. FWIW.....

**ThomasW** · 28 June 2004, 20:53 Monday

Hi

Yes I run my 400Q with a UPS for just the reasons you described. It has a programmed cool-down cycle with the fan running for several minutes.

My CRT projector has no such operation. Turn off the PJ and immediately everything powers down.

**Hank** · 28 June 2004, 22:11 Monday

Dennis, the temperature of a digital PJ is many hundreds of degrees hotter than any CRT - that's the reason for the slow cool-down to avoid overstressing the glass in the digital PJ lamp. The densly-packed circuit boards of a CRT projector are the heat concern with those PJ's

configurated

Jon: Gotcha! Yes!!

arty:
I am the FIRST to catch Poobah Jon in a gutter-botching of English! What's the prize? - A trip to the Caribbean? After all, it's been three years, and I NEED to SCUBA dive for corporate Dilbert job stress-relief. C'com, send the prize money! :B

**ThomasW** · 28 June 2004, 23:45 Monday

Hank

Jon is slowly learning 'Bush-speak' ............

BTW, since I can't use a balanced transformer for the CRT, I'll have extra units. All along I was thinking about making up a demo balanced power unit and sending it around for people to audition. Is this something that you would be interested trying? Note, I'm not offering any for sale. The idea is for people to audition and then build their own they want one.

**David Meek** · 29 June 2004, 08:48 Tuesday

Originally posted by Thomas

Jon is slowly learning 'Bush-speak' ............

He talks to plants?????

: I was gonna say "vegetables", but someone might misconstrue that as a political comment, ya know? :B

Originally posted by Thomas

BTW, since I can't use a balanced transformer for the CRT, I'll have extra units. All along I was thinking about making up a demo balanced power unit and sending it around for people to audition. Is this something that you would be interested trying? Note, I'm not offering any for sale. The idea is for people to audition and then build their own they want one.

Thomas, that's an amazingly nice thing to do! I'd like to get on the circle-ayshun list (see, I can talk just like Jon :W ), especially since the "build sumething" bug is biting hard right now.

**ThomasW** · 29 June 2004, 10:10 Tuesday

Political comment? Who me? Never....

This project is slowing down. For some reason our pals at PE have been 'processing' my transformer order for 2 days. I was expecting them to ship on monday. :huh:

Anyway, I'll build up a unit for people to audition. Then make a sign-up list and we'll sent the transformer on a trip around the country.... :T

**Brandon B** · 29 June 2004, 10:26 Tuesday

Originally posted by Hank

I am the FIRST to catch Poobah Jon in a gutter-botching of English!

Can I claim one for non-english? Thank you is typically spelled "arigato gozai mashta".

On the lamp cool down for digitals question, we have been told by at least 5 different manufacturers' engineers that the fan remaining on after switching off a PJ is to cool it down faster so restrike can happen sooner. Secondarily, it is to continue to circulate air in the case for the benefit of the electronics, as they might see higher temperatures in a just-turned-off, fan-off PJ than in one in full operation, for a short time any way. It allegedly has nothing to do with lamp life. Why would it stress the lamp less to cool it faster? Not gospel, but FWIW.

BB

**David Meek** · 29 June 2004, 10:44 Tuesday

Originally posted by Brandon

Why would it stress the lamp less to cool it faster?

Just some non-EE thinking aloud here: When you bend a wire back-and-forth slowly about a point, it will allow that to be done multiple times - when you bend it back-and-forth quickly (more heat, generated faster), many times it will break. Shouldn't the same principle apply to the cool-down of a bulb - slower would be better?

If it applies, just tell me to go sit in the corner and quit trying to think. :scratchhead:

**JonMarsh** · 29 June 2004, 10:53 Tuesday

Originally posted by ThomasW

Hank

Jon is slowly learning 'Bush-speak' ............

Yes, since I've been traveling to Texas a lot on business lately, as part of our corporate cultural sensitivity training, I've been receiving special instruction in how to adapt to favored local dialects, as ThomasW so succintly points out.

The true measure of adaptation is not just being able to use the dialect fluently on a planned basis, but integrating it so thoroughly into one's responses that it becomes second nature even when dashing out urgent posts in the middle of ongoing crises at work; i.e., high stress conditions. Displaying this ability to "stay in character" shows true adoption of localized culturalated norms.

This is thought to have a postive impact on the long term financial remuneration from replicated visitations.

~Jon :W

**ThomasW** · 29 June 2004, 10:54 Tuesday

Can I claim one for non-english? Thank you is typically spelled "arigato gozai mashta".

When I was there we typically said "domo arigato" and did a mild polite bow....

If we were with a big-wig we said "domo arigato gozai mashta" and hit the floor with our foreheads when we bowed..... :B

**David Meek** · 29 June 2004, 13:27 Tuesday

Originally posted by Jon

Yes, since I've been traveling to Texas a lot on business lately, as part of our corporate cultural sensitivity training, I've been receiving special instruction in how to adapt to favored local dialects, as ThomasW so succintly points out.

In the interests of clarity, state pride and political nose tweaking, I MUST once again strive to educate the un-washed masses. Let's NOT confuse Bush-speak with Texas-speak. :W He was born in New Haven, Connecticut, so any attempts to sound like a true Texan have been/are/will be filtered through that base layer of Yankee-speak. Now, the First Lady IS a native Texan (all bow. . . . you may rise) and her Bush-speak is the real thing. Thank you for your time and attention to this oh-so-trivial-but-important matter. :B

Originally posted by Thomas

hit the floor with our foreheads when we bowed

Hmmph, the only time a real Texan hits the floor with his forehead is when it involves the earlier consumption of a large amount of beer or tequila. Or he lips-off to his wife one time too many. YMMV. :bash:

Uh Hank, you out there? I may need backup momentarily. . . . (sounds of running into the closet for the bulletproof vest) :a>

**ThomasW** · 29 June 2004, 14:38 Tuesday

David,

Just to clarify....if a person is saying

"domo arigato gozai mashta"

They ain't in Texas .... :B

**Brandon B** · 29 June 2004, 15:46 Tuesday

Originally posted by David Meek

Just some non-EE thinking aloud here: When you bend a wire back-and-forth slowly about a point, it will allow that to be done multiple times - when you bend it back-and-forth quickly (more heat, generated faster), many times it will break. Shouldn't the same principle apply to the cool-down of a bulb - slower would be better?

If it applies, just tell me to go sit in the corner and quit trying to think. :scratchhead:

That's my point. With the fan on, the lamp will be cooled down faster. If the fan went off at the same time as the lamp, the lamp gets to cool more slowly.

Hence my acceptance of the claim from the engineers that the fan-assisted cool-down is to allow for faster restrike of the lamp, rather than controlled cooling of the lamp.

BB

**Brandon B** · 29 June 2004, 15:50 Tuesday

Originally posted by ThomasW

When I was there we typically said "domo arigato" and did a mild polite bow....

If we were with a big-wig we said "domo arigato gozai mashta" and hit the floor with our foreheads when we bowed..... :B

I was just picking on the gazai vs. gozai spelling.

The bowing thing was my worst hangup when I moved home 3 years ago. Took me 6 months to stop bowing to people when they held a door, let me cross the street, etc. Got a great many "what's with you, oddball?" looks in response to the bows. Even now, takes me 2 days to stop after a 1 week trip over there. Gaaa!

BB

**ThomasW** · 29 June 2004, 15:58 Tuesday

I was just picking on the gazai vs. gozai spelling.

ALthough he wasn't born there, Jon obviously spent TOO many years in the public schools in east Texas. Hence his problems with spelling........ :E

**David Meek** · 29 June 2004, 17:35 Tuesday

Originally posted by Brandon B

That's my point. With the fan on, the lamp will be cooled down faster. If the fan went off at the same time as the lamp, the lamp gets to cool more slowly.

Hence my acceptance of the claim from the engineers that the fan-assisted cool-down is to allow for faster restrike of the lamp, rather than controlled cooling of the lamp.

Gomen nasai Brandon. :W I meant to make it clear that what I was asking was in support of your post.

Ja ne, for now. :later:

**brucek** · 29 June 2004, 18:21 Tuesday

That's my point. With the fan on, the lamp will be cooled down faster. If the fan went off at the same time as the lamp, the lamp gets to cool more slowly.

My understanding is that the fan remains on after the lamp is shut off so as to create an 'even' cool down to avoid thermal buildup.

In the on state, the lamp runs extremely hot, but the fan is consistently removing that hot air envelope around the bulb. If the fan and bulb are turned off simulataneously, heat would quickly build up around the lamp, potentially damaging it.

Leaving the fan on, allows an even cool down, increasing the bulbs life.......

**Brandon B** · 30 June 2004, 10:53 Wednesday

Originally posted by brucek

In the on state, the lamp runs extremely hot, but the fan is consistently removing that hot air envelope around the bulb. If the fan and bulb are turned off simulataneously, heat would quickly build up around the lamp, potentially damaging it.

Sounds good, unless you examine it closely. So you are saying heat which the lamp emits leaves the lamp, and then comes back into the lamp and heats it up higher than when it was on?

Not baggin' on you, as I used to think this also, but the projector companies' engineers are telling me this is not the case.

Guarantee the amount of heat created internally by the lamp when it is on is FAR greater than what it might absorb from hot air externally after it is switched off. The cool down is not to protect the lamp.

BB

**JonMarsh** · 30 June 2004, 12:08 Wednesday

The cool down is to protect the near by electronic components in the lightpath, which will get toasted by the residual heat from the bulb if it's just turned off without any continuation of airflow. Especially a problem with LCD projectors, as the polarizers and LCD chips are not as tolerant of high temps as DLP chips.

~Jon

Let's face it guys, bulbs belong in lamps, not video projectors!

:rofl:

Regards,

Jon

**Brandon B** · 30 June 2004, 12:28 Wednesday

Concur with that. LASERS belong in video projectors. And soon, oh please oh please oh please.

BB

**ThomasW** · 10 July 2004, 14:53 Saturday

Okay lets get this thread back on track.

I put feet on both cabinets. Then installed the power cord and fuse holder in the small one.

HERE'S an article link for broadband users.

Pic #8 and Pic #9 for those using dial-up

The hole in the bottom of the little box is for the transformer mounting bolt.

Note for those thinking this is overly simplistic, this is supposed to be a step-by-step tutorial....... :T

**ThomasW** · 11 July 2004, 16:59 Sunday

Starting on the actual assembly with a new webpage. Broadband users click HERE.

For those with dial-up, here are the individual pictures

Pic #10
Pic #11
Pic #12
Pic# 13
Pic #14

**JonMarsh** · 11 July 2004, 19:40 Sunday

Looking good, Thomas. What are these gonna cost when we do a power buy?

~Jon

**ThomasW** · 11 July 2004, 22:14 Sunday

$99 is going to buy YOU a pile of parts ....... :wink:

Cheap DIY balanced power device

Cheap DIY balanced power device

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