N.E. "VU" Meter With Interesting Circuit Construction

[Ktownphoneco]

I spotted this Northern Electric "VU" Meter on eBay this morning, and thought the circuitry construction / design was somewhat unique as far as electronics is concerned.     The 2 batteries also appear somewhat unusual.    They appear to have the physical appearance of a standard 9 Volt battery, but the positive and negative terminals are located at each end rather than having both at one end.     Perhaps they're available commercially, but I've never seen one.      The battery holder is also unique in it's design.
eBay Listing Link :     http://www.ebay.com/itm/162274357810?ul_noapp=true

Enjoy the day.

Jeff Lamb
   

[Holtzer-Cabot]

Wow! Very cool, thanks for sharing! The case reminds my of one of my tube testers, a Superior Instruments Co. Model TV-11 in a dovetailed oak case.

[rdelius]

The batteries are 22.5 V 

[Ktownphoneco]

Thanks for the additional information on the batteries.    That would explain why I'm not familiar with them.     But now that you've pointed out the voltage, I see they're actually fairly easy to come by, but just a little expensive depending on the make and / or where they're being sold.   

Jeff

[TelePlay]

And, they are in series - a 45 VDC source.

And on a quick search, I'm finding $25 per battery. Is that what you are seeing? That is pricey.

[Ktownphoneco]

The ones that I priced were anywhere from $10.69 Canadian for some brand name I've never heard of called "Atlantic" ( that's probably Atlantic in China), to $33.54 for one selling under the "Excel" brand, which I have heard of.
I looked at the series / parallel battery situation as well.      It's puzzling.   There are 2 conductors.  One at each end.    The batteries look like that Atlantic brands I mentioned, and both have the "Black" colored ends sitting side by side, but one battery is showing the opposite end showing as (+)positive, while the other battery is showing the opposite end as (-) negative. 
I'm assuming that because they're probably the "el-cheapo" brand, that there was a mistake at the factory where they were made, an the one battery had the markings switched.   Both end brackets with the screw in battery connection points seem to have a solid electrical connection with each adjacent end plate.   If the positive and negative ends were switched and mounted in the battery bracket that way, there'd be more or less "zero" voltage to the meter itself, and the batteries would be shorted.

Jeff

[TelePlay]

Yes, bad packaging.

Found this listing for an Atlantic battery on eBay, $11 cheap.

http://www.ebay.com/itm/2Pcs-15F20-22-5V-Battery-412U15VS084-MN122-Carbon-Zinc-High-Capacity-ATLANTIC-US-/320928427174

Notice the markings on the two photos in the listing. One shows the "+" mark on one side circled in yellow along with the 22.5 V markings and the other side shows not only a "-" sign but also a marking saying it is a 9 VDC battery. The seller put the markings in red on the image, I put a yellow box around it. So, Atlantic used 9 VDC shells to hold the 22.5 V stack and put a terminal on each end rather than the two terminals of a 9 V battery side by side on one end.

[AE_Collector]

22.5 / 45 volt batteries were fairly common in old telephone test equipment. I always wondered why 24 / 48 volt wouldn't have been a more easily explained choice of voltages. I wonder if the voltage originated from old battery powered radios?

Terry

[Ktownphoneco]

Yes, it's way beyond "sloppy".  Safe to say, Atlantic doesn't have a quality control department.    One would really want to check each battery with a volt meter to verify polarity before they installed the batteries.

Yes, they certainly used a range of different voltages over the years.    The engineer(s) who designed the meter, probably settled on what they felt was a proper voltage for the unit, without any regard for what was readily available and already in use with other company products.     But that's a guess at best.

Jeff
 

[Fabius]

I like the resetors and capacitors all in a row in a wood? rack.

[TelePlay]

22.5 / 45 volt batteries were fairly common in old telephone test equipment. I always wondered why 24 / 48 volt wouldn't have been a more easily explained choice of voltages. I wonder if the voltage originated from old battery powered radios?

Terry

Well, 1.5 volts times 15 is 22.5 volts and double that, 30 volts times 30 is 45 volts or 22.5 volts times 2 is 45 volts. Must have a lot to do with the original lead acid batteries. Car batteries have 4 cells (6 volts) and 8 cells (12 volts). IIRC, alkaline cells are a bit "hotter" so when I put a 1.5 volt reference battery in a tube tester, it could not be an alkaline battery. At least, all this would be my guess.

[Jim Stettler]

5-9 volts in series  will give you a cheap 45 volt battery. It won't fit in the meter, but it will give you a good 45 volt battery for testing purposes.

JMO,
Jim S.

[AE_Collector]

Car batteries have 4 cells (6 volts) and 8 cells (12 volts).

Lead Acid batteries come off at something like 2.15 volts per cell rather than 1.5 volts in carbon zinc, alkaline etc. A 12 volt car battery has 6 cells.

Strings of lead acid batteries in telephone offices were 24 cells long though years ago in SxS offices we had strings of 26 cells where the 25th and 26th cells were charged but not initially in the string. When running on battery only once the voltage dropped to a certain level the two "end cells" we're automatically cut in to the circuit boosting the voltage of the string for a few more hours.

5-9 volts in series  will give you a cheap 45 volt battery. It won't fit in the meter, but it will give you a good 45 volt battery for testing purposes.

JMO,
Jim S.

In more recent years many of the "odd" telephone related batteries had strings of AA or 9 volt batteries inside the package. Sometimes there was a lot of vacant real estate in the battery package with a couple of 9 volts in the bottom etc.

The 45 volt batteries used in break down boxes (batteries were roughly the size of today's 4 Amp Hour alarm system batteries on the outside) had 30 AA batteries inside soldered in series inside. Break down boxes had somewhere between 12 and 16 of these 45 volt batteries in series. If a cable pair had a partial short usually due to water getting in somewhere, they would put the break down box onto the pair after opening the protectors on each end. In almost all cases the pair would either be open or have a dead (welded together) short after around 600 volts DC finished with the partial short. Then they could use other equipment to determine where the fault is or was to do repairs.

Terry

[TelePlay]

Ah, couldn't think of the word that went with carbon. Took a lot of those apart for the carbon rod years ago. Went with lead acid in error and yes, you are right, there are only six selves in a 12 volt car battery. 8 did not seem right. Old memory failing fast.

[19and41]

Nice price for such an attractive little unit.  It looks like it was built in a prototyping shop.  A good one.