Building "The Cheapskate!" 

($125 or less)

Balanced Power Unit

Page 1
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I've been using balanced power devices for quite a few years. And have been very please with the improvements they provide. Unfortunately during that time, the pricing for these has gone up, and up, and up. There's no rocket science involved in these, primarily it's just a special transformer, and AC outlets. As a result I decided to make up a couple of simple DIY devices using readily available parts. One can add in low cost 'options' such as RFI/EMI input/output filters if desired. These will improve the performance of the unit.

Instead of trying to explain what BP is and how it works here's a link to the Equi=Tech FAQ page. This is a very comprehensive FAQ.

Note: 1) These devices DO NOT provide surge protection or voltage stabilization. They can of course be plugged into standard OTC surge devices or surge devices can be plugged into them. DO NOT exceed the recommended VA rating of the transformer. That rating is 800VA. If you don't know how to calculate the amount of power used by your gear here's a LINK to a online Java script load calculator. It's used to calculate the load for computer UPS devices. But it's fine for our needs too.

Note: 2)DO NOT plug receivers or power amplifiers into these relatively small transformers. Receivers and power amplifiers are DYNAMIC loads*. They can quickly exceed the 800VA rating of this transformer. These units are designed and intended for FIXED load devices only. (DVD/CD players, tuners, pre-amps, TVs, VCRs, etc)

*Receivers and power amps do benefit from the effects of balanced power, but significantly larger transformers must be used. We have a 2000VA project in the works. We'll publish a separate article detailing it's construction at a later date. 

Note: 3) As with any DIY project, these units are NOT UL or CE rated or approved. Use at your own risk.

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Parts List:

1) Avel Lindberg transformer from Parts Express (P/N 122-720)
2)  *Chassis 10"X10"X4" or 8"X8"X4" indoor AC junction box. 
3)  *Single outlet AC receptacles
4)  *AC power cord, Note: one can certainly use an IEC chassis connector and cord (see #14 below)
5)  Chassis mount AC fuse holder. I used Parts Express (P/N 070-061)
6)  *10 amp slo-blow fuse
7)  *14 or 16 gauge hook-up wire (having 3 different colors is a good idea)
8)   4-Rubber feet I used Parts Express (P/N 260-773)
9)   * barrier strips or terminal strips for wiring points 
10)  * misc hardware; nuts, screws, lock-washers, wire-nuts, etc.

The items below are optional, but recommended. Note; the inline RFI/EMI filters can be added as an upgrade after the device has been built.

11) low mfd, high voltage non-polarized film caps. The value of these caps isn't critical, but they should be relatively small (less than 1 mfd, bigger in this case isn't better). The cap's power handling however should be adequate to the task (600V min). On hand I had some .22 mfd 1200V GE caps purchased at Madisound. One cap is used as a differential noise blocking cap for each AC outlet used. Note; the industry 'standard' is to use what are called X2 caps on AC outlets. If one uses the non-X2 caps; and if the unit passes a high voltage transient the caps will fuse (short), and need to be replaced. Unlike X2 caps these regular caps aren't 'self-clearing'.
12) CL-30 NTC resistor, the inlet rush of current when the transformer is powered up, could cause circuit breakers or fuses to pop. Use of one of these creates what's called a 'soft-start', cutting down the in-rush current. Mouser (P/N 527-CL-30)
13) EMC (RFI) block filters (Mouser (P/N 693-5500.2042)  ( Use one filter per AC outlet)
14) IEC connector with built-in RFI filtration Mouser (P/N 693-5110-0843.3)
15)  *1/4" fully insulated crimp-on wire connectors (these are used with the RMI/EFI filters)

Note that each EMC filter is rated at 8 amps. This allows one single higher draw device to be plugged into one outlet, thereby utilizing all the power the transformer can supply. The 8 amp rated devices still allow EMC filtration for devices that don't draw a full 8 amps.

Note items marked with an (*) are readily available from home center stores or larger hardware stores.

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We start with a stock indoor 8"X8"X4" junction box. These are readily available at most home center stores for about $14. This particular box is designed for the larger sizes of wire/conduit, and as a result has very large knock-outs.

Remove the knockouts one section at a time, starting with the smallest and work out to the larger rings. Be careful, as the holes becomes larger the tendency is for all the rings to start moving. We want to be careful and keep the last ring in place

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Next we trim the ears off the receptacle. I put them in a padded vice and used a hack saw to remove the metal

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With the ears removed, place the outlet upside down over it's new opening. Mark where to drill the holes for the mounting screws. Note if you mess this up don't worry. Nuts and machine screws can be used. 

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Here the receptacle mounting screw holes are drilled and we're ready to install the outlet.

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Here what it looks like with one outlet installed. There's plenty of room to add a second outlet if needed. Note the box is too small to wire up the outlets when mounted inside. So for now, remove the outlets. Later we'll wire the outlets, then install them in the box. _______________________________________________________________________________________

I decided to work on both the basic and the 'upgraded' boxes at the same time. Here's a shot so people can see the relative difference in the box sizes. The smaller box simply has no room to add filtration or other goodies.

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Funny that the larger box is $2.00 cheaper than the small one.

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Got Feet?

The nice thing is that the boxes already had pre-punched holes in the bottom. So being lazy I just used them.

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Okay, power cord and fuse holder are installed. Now lets start assembling the insides. At this point I'm going to segue to the construction of just the smaller box. There are going to be enough design differences to justify splitting the rest of the construction info into separate sections.
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