Hi all out there. I found a transformer in my basement. I don't know if its a audio-output transformer or just a power transformer. On top it's stamped "GALVIN MANUFACTURING CORPORATION", and a model #: "25B31296-E" and a serial# ( ???? ) "138226" At bottom there is 8 solder lugs, stamped: "1 to 8". And at one side is 8 screw connector, labeled as "3A 12 11 2B 2A 10 1A 9".
To me it looks more like a tube output transformator, more than a power transformer. It seems to be from the 1940 or somewhere around there.
Anyone know what it is, and have some kind of "schematic" of the transformer.
Galvin Manufacturing is the company that produced Motorola products out of Chicago, Illinois, USA. It is easy enough to trace it out using a small AC power-supply and a good True RMS VOM.
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takes you to the RMA (Radio Manu facturers' Association) Transformer color-code for power transformers. Moto rola, being a founding member of the RMA would typically follow these codes , but for their military stuff that followed a different code, sometimes.
Audio Output Transformers usually have Green-Black-Green (and mixes) on the secondary side, and Blue-Red-Blue (and mixes) on the primary side.
Note that transformers often have multiple taps on the same winding. So: a) Using your Ohms setting isolate the various windings from each other. A single winding will show continuity, but with variations in resistance from one tap to the next. b) Isolate the windings from the lowest total resistance to the most total resistance - this is trickier than it seems as you want to include all taps , but measure the complete winding, not an internal tap. Even more so, if, for instance, you have a 5V winding off a 120 V primary - it will have a lo wer resistance than the primary winding - more on this later. Bundle each w inding and all the taps together so as not to mix them up. c) Starting with the lowest-resistance winding, apply some reasonable, but low, AC voltage -say about 20 VAC or so. d) Measure voltages on the other windings. By experimentation, you should b e able to discern the purpose of the transformer, the primary winding and a ny taps, and the secondary windings as well.
As an example: A typical audio power for tube equipment here in the US woul d get 120 VAC on the primary side, have a B+ winding that might give someth ing between 325 and 450 VAC, one or two 6.3 V filament windings and, perhap s a 5 V filament winding. That would be as many as five total windings. Som e few even have dual primary windings to accommodate multiple input voltage s. So, it is complicated.
An audio transformer may have multiple taps, but the turns ratio between th e primary and the full secondary will be fixed, and there will be only two windings in total.
Take your time - it is almost entirely unlikely that you will be able to tr ace *that* transformer by its part number.
Audio output transformers generally don't interleave the "E" and "I" laminations, and may have an obvious bit of waxy paper between the block of E and I laminations. Power transformers almost invariably do interleave the laminations (I've never seen one that didn't).
Galvin Manufacturing was the original radio manufacturing company that eventually became Motorola. They started making consumer radios, and then invented a record player that could be installed in an automobile. Thus, came the name MOTOROLA, from MOTOR cars, and the old victROLA record player (from RCA). The 25B31296 part number identifies as a Motorola transformer, having the following characteristics from the US military stock system:
5950-00-648-0404 Features MRC Parameter Characteristics ABKQ Center to Center Distance Between Mounting Facilities Parallel to Length 2.625 inches nominal single mounting facility single center group ABKR Center to Center Distance Between Mounting Facilities Parallel to Width 2.375 inches nominal single mounting facility single center group ABTB Mounting Hole Diameter 0.125 inches nominal single group ACZB Frequency Rating 60.0 hertz nominal single component ACZC Input-Output Phase Relationship Three phase to three phase single component ADAQ Body Length 3.875 inches nominal ADAT Body Width 3.875 inches nominal ADAU Body Height 3.500 inches nominal AKNA Inclosure Type Hermetically sealed AKPV Mounting Facility Quantity 4 single group AXGY Mounting Method Flange single group and unthreaded hole single group BPLC Winding Function and Quantity 1 primary single component and 2 secondary single component CWJS Winding Operating Voltage 145.00 ac volts nominal single component 1ST secondary CWJS Winding Operating Voltage 12.00 ac volts nominal single component single primary CWJS Winding Operating Voltage 5.80 ac volts nominal single component
2ND secondary TTQY Terminal Type and Quantity 8 threaded stud and 7 tab, solder lug
No indication of the equipment it was used in, but more than likely a piece of military equipment. Since the primary is specified as 12VAC, and secondaries as 145V and 5.8V, it is likely to be a power transformer from a vibrator power supply used in a military radio of some sort. Don't know how the 3-phase spec works into it... could just be how the vibrator side of the transformer was described.
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** I've seen a portabe 45rpm player where the disk slid into a slot like bread in a toaster. The arm was held against the vinyl surface by spring pressure.
Crystal PU, of course, with no vertical compliance - a real "groove straightener".
Cars had soft suspension & poor handling in the 50s, the ideal combination. Add a high tracking force xtal pickup and it ain't that hard. But they still skipped here & there.
Den fredag 27 september 2019 kl. 19:48:15 UTC+2 skrev Bo-Lennart:
Thank You all for the reply. I understand that there would be easier if I could present a picture of the transfprmer. I have pics, but I don't know how to present them here in this group. I did some measuring with my L-meter, so I now know where the coils are. I'm pretty new to this group. Please tell me if I can present a picture right here in these group. Or can I present a link to eg. One Drive or DropBox or similar....
Welcome aboard, friend! Unfortunately we have a few nutters here but take my advice and just ignore them. ;-)
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Den fredag 27 september 2019 kl. 19:48:15 UTC+2 skrev Bo-Lennart:
I have uploaded som picture of the trafo. And I made a schematic of the transformer. Here is the links:
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Well, I'm an old man (turned 70 early this yr), and I started my electronic profession very young. At that time the car radio had VIBRATOR to make 12V (or 6V) transformable. And I start to think that it's a such transformer. The screw-terminal could be switchable betveen 12 and 6 Volts use ?????. How about that? Anyone have a better suggestions?
Never knew Motorola started as Galvin Mfg Corp: . That tranny could be a real museum piece!
Could you double check the inductance between 7-8? The combination of much higher inductance and still a low DC resistance looks suspicious. Was it not 3.08 mH? Then it could be the separate filament output for an HV rectifier tube.
The HV output for a vibrator transformer would have high resistance (like 4-5-6) but a much higher inductance than the input windings, and it isn't. Also suspicious.
Some 50 years ago I've repaired an old 12V (or 6V?) input tube car-radio, and it had a vibrator inverter. However, the transformer was much less complicated: just two primary and two secondary windings. There was no rectifier tube, the vibrator also rectified the HV. The tube filaments were directly run on the incoming 12Vdc.
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