flyback transformer- identifying the pins

[arnab321]

**broken link removed**
this is the site which everyone had been recommending, but im not able to solve my problem with it.

my transformer is a china made one,typing whose number doesnt bring up any datasheet. it is JF 501 - 19526

moreover i also need to identify the feedback coil pins....

my transformer had 10 pins in the horseshoe and 2 wires sticking out- one red and one grey, besides another thicker wire with the suction cup.

can u tell me what are these 2 wires for?

and this is my ohmmeter reading- can u plz identify the primary and feedback coil from this data?
pin 1-2 0.8Ω
1-9 0.8Ω
2-9 0.2Ω
3-4 0.1Ω
3-6 0.7Ω
3-7 0.3Ω
3-8 0.3Ω
4-6 ------initially 0.6Ω and it gradually started decreasing to 0.2Ω
4-8 0.2Ω
6-7 0.3Ω

 

[DerStrom8]

Hello, arnab321.
The thick wire with the suction cup at the end is your high voltage rectified output. This is where you will get your (usually) 10kv-40kv out. The thinner red wires are usually for things like focus, which you probably don't want to worry about. As for the horseshoe design of the pins, the pattern is different for various transformers. The only way to really tell which pins are in and which are out would be to experiment. Usually the power input pins are next to each other, and towards one side of the horseshoe. Once you find the right ones, you can find the ground pin by holding the suction cup wire near the others (NOT THE POWER PINS!) and see which one it arcs to most. The ground, in my experience, is generally towards the middle.
I hope this helps!
Der Strom

 

[arnab321]

thnx, it helped partially.
do u think pin 1 n 2 can be the the primary coil? (look at the ohmmeter readings in first post)
any way to identify the feedback coil?

 

[DerStrom8]

Pin 1 and 2 could very easily be the primary. They seem to have the right resistance.

There are many "feedback coils" within this one--there is no single one called that. I would suggest trying 3 and 4 as the feedback, but that is no guarantee. Pin 4 could be ground. What are you using for a driver?
Der Strom

 

[arnab321]

Pin 1 and 2 could very easily be the primary. They seem to have the right resistance.

There are many "feedback coils" within this one--there is no single one called that. I would suggest trying 3 and 4 as the feedback, but that is no guarantee. Pin 4 could be ground. What are you using for a driver?
Der Strom

well, i assumed pin 1 and 2 to be primary and tested for the ground.... getting pin 10. pin 9 gives lower voltage than pin 10. and im 100% sure its not pin 8. (most of the FBTs hv pin as ground) but when i use pin 10 as ground, this happens: (see 1st post in the link)

https://www.electro-tech-online.com/threads/flyback-transformer-is-the-output-rectified.119285/

anyways, ill post whether 3-4 works as the feedback, soon.

 

[arnab321]

**broken link removed**
using this as the driver, im gettin 0 volts as the HV output if i assume 3 and 4 as feedback pins

 

[carbonzit]

You have, of course, tried reversing the connections to one of the windings?

 

[arnab321]

You have, of course, tried reversing the connections to one of the windings?

yes i have.
im connecting the primary with correct polarity, and i tried reversing the 3-4 connection. still no luck. im using 9V 850mA adapter as the power supply. but im getting 0V, 0A from the HV

 

[arnab321]

thnx alot, thnx alot ppl...... pin 3-4 is indeed the feedback coil.... it wasnt working due to some loose connection earlier....

 

[carbonzit]

CongratulaZAP!!!!!tions.

 

[arnab321]

CongratulaZAP!!!!!tions.

lol...

i wanna know 1 thing..... the PS for the driver is 9v 850mA adapter. and the spark is only 0.5 cm long (looks like output is 3-5kv, well i dunno) and i get a low pitch buzzer sound. (werent we supposed to get a high pitch sound?) is such a low voltage output expected ?

 

[debe]

Most TV flyback TF put out 25KV, but are powered by about 100V, 9V is not going to reach that voltage.

 

[DerStrom8]

Another thing is that that particular driver works best with the older style FBTs, not the newer ones like what you have. It is intended for a transformer like this one:

**broken link removed**

Have you considered trying a 555 timer based driver? Here's on that is specifically designed for your type of FBT:

**broken link removed**

Just something else to take into consideration
Der Strom

 

[arnab321]

- i tried running the driver (schematics already posted in this thread), from a 12V 7Ah battery, and i did get a loud high pitch sound, like a very shrill like a car screeching, but i think i was supposed to get a whizz sound...
- the spark i get was still not powerful and was almost the same as what i got with 9V input. and the spark doesnt happen continuously, but once in a while.

- will the 555 driver posted by DerStrom8 give a better spark?
- and.... cant i get a good spark with simple 2n3055 drivers like the one posted, with feasible input PS?

 

[arnab321]

i need to identify one more pin for making the zvs driver:
**broken link removed**

can u plz make out which would be the middle wire from primary coil from the ohmmeter readings in my first post?

 

[DerStrom8]

i need to identify one more pin for making the zvs driver:
can u plz make out which would be the middle wire from primary coil from the ohmmeter readings in my first post?

You would need to wind your own primary for that driver. As the diagram says, 5+5 turns on the ferrite core, meaning wind 5, give it a loop and a twist for the center tap, and then 5 more.

 

[arnab321]

You would need to wind your own primary for that driver. As the diagram says, 5+5 turns on the ferrite core, meaning wind 5, give it a loop and a twist for the center tap, and then 5 more.

i suppose thats not possible on modern type FBTs???

 

[DerStrom8]

i suppose thats not possible on modern type FBTs???

It is possible, but it may be difficult. At least it's only 10 turns.

 

[arnab321]

It is possible, but it may be difficult. At least it's only 10 turns.

like this???
**broken link removed**

 

[DerStrom8]

like this???
**broken link removed**

That looks pretty good. Just make sure you have the tap between the two windings.