Electronics > Beginners
Identify giant transformer from 1978 tape reel
queennikki1972:
1st side
2x red
2x orange
1x yellow
1x white
1x blue
Second Side
2x green
1x purple
1x gray
1x brown
1x black
MarkF:
I too had a transformer that I could not identify.
I started by measuring the resistance of each coil. At which point you can identify each coil and whether you have any center tapped windings. From the resistance you can probably guess which are the primary and which are the secondaries. I suspect that you have a dual primary and multiple secondaries. After I identified the primaries, I plugged mine in and measured the voltage on each secondary.
When you plug it in, you will want to limit the current. Something like a light bulb in series.
If you do this, use an old incandescent light bulb. None of the new fluorescent or LED bulbs.
Jwillis:
Transformer winding configurations can vary so much it would take a library just to catalog then all.
Many transformers have multiple voltage configurations at the primary that are not limited to the standard 120VAC and 240VAC. It' very much dependent on application .For example ,a UPS transformer I have has 80VAC ,100VAC ,120VAC and 130VAC with a 15-0-15 and 20v secondary..By switching the primary the voltages at the secondary can be changed for the bulk ,saturation and float charge of the batteries .These multiple primary transformers are also in a lot of car battery chargers that set the output voltage and amperage for trickle charging ,fast charge and starter boost by switching the primaries.
Some multiple Primary transformers are set up for various countries.
In a lot of cases its just more practical to put secondaries on the same side as the Mains primaries.
But for safety sake don't arbitrarily plug high voltage in without knowing which is what .
Use a multi meter to find which wires have continuity with each other and draw up a schematic .Then use a know transformer with a low voltage of say around 24VAC as a power supply.Then you can measure voltage and document your findings.This will show ratios between the primaries and secondary winding s then just do a little math to find the potential voltage of each .
Jwillis:
The biggest problem with using a lamp to find how a transformer is configured is that the light draws current and some winding s on the transformer may not handle that current and could potentially burn up the winding s . The safest way is to use low voltage AC instead and measure with a multimeter .
schmitt trigger:
I had a TEAC reel to reel tape recorder, which had an autotransformer multi-tapped primary. The reason being that the spool motors were fed different voltages depending on its actual function:
1-During play or record, the take up spool motor would receive about 75% voltage, and the supply spool motor about 40% voltage, to maintain tape tension across the heads. The tape speed was of course, regulated by a synchronous capstan motor.
2- During fast forward or rewind, the take up spool motor (could be either side) would receive full line voltage, whereas the other motor would receive about 25% voltage, again to maintain some lower value tape tension.
Of course, you had the multiple secondaries to supply the required electronic voltages. You do not mention whether this tape machine was tubed or transistorized. If tubed, a pair of secondary wires (green-???) were the heater voltages and the remaining could be different V+ voltages.
But again, all of this is speculation. Proceed with the valuable advice from the previous posters.
The *incandescent* bulb in series is a good trick to prevent a severe short circuit. If it lights very dimly, you are fine. OTOH, if it lights brightly, you are overloading that winding. I have used 25 or 40 watt bulbs for that purpose.
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