How to Find the Primary and the Secondary Coils of a FlyBack Transformer

Introduction: How to Find the Primary and the Secondary Coils of a FlyBack Transformer

The main problem, in most cases, is that you don't know the pinout diagram of a flyback transformer. So, I shall try to give you a simple method to find the primary coil input pins and also the 0 V output pin of the HV secondary coil.

-=I do not take full credit for this=-

Step 1: How to Find the 0 V Pin Connection of the Secundary Coil?

With a common digital ohmeter it is impossible to find the secondary coil pinout because its resistance is much too high. The main HV output is simple to find : this is the big red cable with the suction cup, but you need to find the 0 V pin of the secondary coil on the flyback transformer. So, I give you a simple method to find this 0v pin :

a) You need a 24 V DC power supply and a digital voltmeter set in 20 V range. Connect the + input of your voltmeter to the THT ouput plug ( in the suction cup ) and the (-) to the 0V of your power supply. Then, with the +24V output from your power supply, test each pin of your flyback transformer. When you measure a voltage between 5 and 10 V you have found the 0 V pin of your secondary coil. This is very simple... Look at the diagram and the photo below :

Step 2: How to Find the Pins Location of the Primary Coil?

With a simple ohmeter this is very simple, you will find easily the primary inputs because the coil resistance is about 1 ohm 

Step 3: How to Find the Polarity of the Primary Coil?

The purpose is to find the polarity of your primary coil. You need a simple 9 V battery. Connect a digital voltmeter set in 100 V range between the main THT output and the 0 V pin of the secondary that you have indentified in test #1. With the 9 V battery send a short pulse on the primary input, measure the spike of the voltage, then reverse the polarity of your 9 V battery. When you get the max voltage ( about a 30 V spike ) you have found the correct polarity of your primary coil. The (+) is the pin number 2 and the (-) is the pin number 1 in the main diagram.

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    29 Discussions

    0
    bachir.sabri
    bachir.sabri

    5 months ago

    Can you explain this scheme

    images (2).png
    0
    bachir.sabri
    bachir.sabri

    Reply 5 months ago

    HR 6060

    0
    a226263
    a226263

    8 years ago on Introduction

    I'm trying to find the pins to the primary coil. I bought a new flyback a couple of weeks ago. My flyback has 10 pins. I got these results:

    Pins ..... Resistance
    1 + 5 .... 2 ohms
    1 + 9 .... 1.8 ohms
    5 + 9 .... 0.9 ohms

    2 + 8 .... 0.9 ohms

    3 + 4 .... 0.8 ohms
    3 + 6 .... 0.8 ohms
    4 + 6 .... 0.6 ohms
    All the other combinations (i.e; pins 1 + 3) produced no resistance, so that means that pins 1 + 3 are not connected. Conversely, this means that pins 1+5+9 are connected; pins 2+8 are connected; pins 3+4+6 are connected; and pin 7 and pin 10 are not connected to any other pins.

    The first problem is that many of these gave me a resistance close to 1 ohm, so I still don't know which pins to use for the primary coil.
    The second problem is that a flyback should have two sets of connected pins; pins that connect to the primary coil, and pins the connect to the secondary coil. However, I seem to have 3 sets of connected pins (or five sets, depending on how you count). Does this mean something is disconnected inside my flyback?

    I didn't know what to do, so I just went ahead and connected it to the CFL circuit. I tried pins 5+9, 2+8, and 3+4 as the pins to the primary coil, along with every combination of the 4 pins on the CFL circuit, but did not get a single arc for any of them. Does this mean that my brand-new flyback is bad?

    0
    Sikhumbuzo Cele
    Sikhumbuzo Cele

    Reply 7 months ago

    The thing is some pins (3 pins which a have resistance value 1 pairs of the 3 pins have a resistance of more than 1 kilo ohm....that does NOT show contact or short) pins that a connected should have a resistance that is measured in ohm NOT kilo ohm. Basic electronics 101😂😂😂😂😂😂😂😂😂😂

    0
    crazy-blender
    crazy-blender

    Reply 8 years ago on Introduction

    it might be bad double check with each set of pins and if it still does not work buy another flyback and see if it works

    0
    ARJOON
    ARJOON

    9 years ago on Introduction

    don't forget guys. ac from wall socket will not work. frequency is too low.

    0
    vreeland
    vreeland

    Reply 3 years ago

    using a fluorescent ballast as a driver into the primary puts out some serious voltage. i would suggest submerging the whole thing in mineral oil so as to prevent any shorts before using it to create any really high voltage (10k - 50k volts)

    0
    vreeland
    vreeland

    Reply 3 years ago

    you can even use a driver from a CFL. plenty of videos out there on youtube and such about it.

    0
    ARJOON
    ARJOON

    Reply 3 years ago

    thanks for the late reply but i've learnt much more in the past six years. thanks anyway

    0
    R.A.T.M
    R.A.T.M

    8 years ago on Introduction

    so i know what the main THT out put is but i have 3 other wires hanging about what are they 4

    0
    vreeland
    vreeland

    Reply 3 years ago

    probably primary in and a ground. primary in is usually red and white ground is green or grey. i'm just going off the flybacks i salvaged from old crt monitors though.

    0
    delokaver
    delokaver

    5 years ago on Introduction

    I am replacing the volt meter with led and also woks, led is on even only a small light ( I use red one for easy to look at)

    0
    ShubhamR3
    ShubhamR3

    5 years ago on Introduction

    i tried to find primary and secondary for 4 different flybacks . First of all there are many combinations of pins which have resistance of around 1 ohm and for the secondary i got at most 0.6 volts with 18 volts supply.

    0
    Doctor90250
    Doctor90250

    5 years ago

    @ dudes, that's a good question, and if you could use both, could each one be "tuned" to different frequency so that a harmonic resonance is reached, causing the flyback, with the HV return pin earth grounded, to become an actual "Tesla coil"?
    the possibilities intrigue me, lol.

    0
    Bumba Lodh
    Bumba Lodh

    9 years ago on Introduction

    i don't have 24 volts dc power supply but i've 12 volts dc power supply
    please give me a advice

    0
    Jimmy Proton
    Jimmy Proton

    Reply 9 years ago on Introduction

    That might work, if it does then you should see around 3 volts on your meter.