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Porcupine Transformer

Discussion in 'Datasheets, Manuals and Component Identification' started by Al Slitter, Dec 24, 2018.

  1. Al Slitter

    Al Slitter

    Nov 4, 2016
    Greetings All;
    I have been cleaning out my shop and organizing some items and came across this smallish transformer that I salvaged some time back.
    The size of the transformer is W=19mm H=16mm D=7mm
    I checked for continuity on the primary side and it seems fine, on the secondary side there are
    12 wires coming out. It is for this reason that I call it the Porcupine transformer.
    Unfortunately when checking for continuity I was not able to find any. I am sure that the transformer is functional but ????

    Here are a couple of images of it:



    Does any one have an idea of what this transformer it and how to check the secondary winding's???

    Thanks in advance.
  2. Alec_t


    Jul 7, 2015
    Did you thoroughly remove the enamel coating of the wire ends before doing the test?
  3. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Sir Al Slitter . . . . .

    Correct me if being otherwise, but it looks like the RED wrapped portion is being the AC line voltage primary winding and the BLUE wrapped section is being all of the separate and isolated secondary windings.
    With the primary, possibly of having two series coil windings, to let it operate at either 120VAC or 240VAC AC power input voltages.

    If my problem to solve . . . . I would be taking the unpowered unit and start labeling all of the individual wire leads. Then check for wire ends that connect / or / read ohmic continuity, to create either a single windings start and end, or possibly, on some, the two wire sets are having a third wire center tap connection.

    To be on the safe side use a 100 watt / line voltage rated incandescent lamp in series with one lead of your AC power input.
    With no loading on the secondary windings, there should be right up near normal voltage outputs.

    Test and assign all of your AC voltage readings on secondary windings. If they make sense, you might identify the voltages with the transformer type / function.
    If you ever had any tube related equipment . . .that high number of windings might relate to the multiplicity of windings used with / needed for tube design equipment.
    There you might have 2 or 3 ~6.3VAC filament supply windings, a 5V rectifier filament winding and then a high voltage winding with center tap.
    That mentioned lineup of windings could account for possibly 15 wires being needed.
    Once you see how the different supplied AC voltages are reading unloaded, you might submit them for analysis.
    Then the lamp could be omitted and full line voltage applied to the primary.

    To rate a windings applicable power capability.

    Read the selected winding to be evaluated and rate its value by initially using off the top of the head . . . . ROUGH . . . RUFF . . RUFF . . computational skills.
    Say it is reading 8 VAC, figure that a 10 ohm resistance across it will load the winding about 800 milliamperes and consume about 6.4 watts, unless you are short on power resistors and in that case, you could monitor the voltage and connect about 1/3 to 1/4th that load resistor wattage rating, thus being in circuit just long enough to get a meter reading, then drop the resistor out of circuit.
    THEN . . . to really power rate the winding, you would be using normal line voltage input and meter the AC voltage supplied from the winding. Then you use the amount of loading resistance ***** across that winding that will then load / pull that voltage down 10% from the unloaded reading.
    The resultant voltage read, under load, will be the AC voltage spec of the unit and you compute the power spec and current spec of the winding by using that then known AC voltage and the then required load resistance.
    This is being found true on quality Stancor, Halldorson, Thordarson, Meissner or Triad transformer manufacturers or that spec is being even better for military / aerospace grades of transformers.
    THEN . . . .there are some imported transformers . . . to wit . . . . some Radio Sh/ack/ysters or Chin-ee transformers that will be found to load down and pull down the loaded voltage upwards of 20% !.

    ***** POWER Load resistors
    In order to create near / close / proper values, I sometimes am finding my self having to incorporate a half a cupfull of power resistors, with all then being appropriately interwired as to take on the
    configuration of a multiple compound - paralello - tandem - series - quasi- push pull -paralell arrangement.

    73's de Edd . . . . .
    . . . . . . . . . .

    There are three kinds of men.

    The one that learns by reading.
    The few who learn by observation.
    The rest of them just have to pee on the electric fence, in order to find out for themselves.
    Richard9025 likes this.
  4. Al Slitter

    Al Slitter

    Nov 4, 2016
    Hello Mr. Alex t :
    Thank you for the response, I checked the transformer and all of the 12 leads have been tinned so I assume the insulation is gone ?
  5. Al Slitter

    Al Slitter

    Nov 4, 2016
    Hello 73's de Edd;
    Thank you for the very detailed response, I will need a few days to go over your response in detail and with Christmas it might take longer do to demands make on me by others.

    Thank you very much.
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