0
\$\begingroup\$

I have this transformer that came from a ccfl inverter and the pins on it are confusing me a bit.

I've tested every pin and only pin 3 and 6 seem to form the primary winding and somehow pin 1 and 8 form a connection? no pins on the secondary seem to form a winding.

why would pin 1 on the primary side connect to pin 8 on the secondary? If pin 1 and 8 form the secondary, why?

enter image description here

other angles

http://i.imgur.com/6zQvw0J.jpg

\$\endgroup\$
  • 1
    \$\begingroup\$ Those positions are there on the form and available, but as you can see they are not all wired up to something. It does appear that you have one coil between 3 and 6 and another coil between 1 and 8. That's all. Getting a wider separation for wiring that goes to the higher voltage coil is probably a good idea for this device. \$\endgroup\$ – jonk Aug 15 '17 at 17:36
  • 1
    \$\begingroup\$ You can see the wire from Pin 1 running up to the split bobbin secondary. Connecting the sec to pins 1 and 8 keeps them well away from each other to simplify isolation. \$\endgroup\$ – Brian Drummond Aug 15 '17 at 17:37
  • \$\begingroup\$ You're comparing this transformer to a mains transformer. In a mains transformer it would indeed make sense to have space out the connections as much as possible for better isolation and to make clear which side is live and which side is not. However, this is not a mains transformer ! To drive a CCFL a high voltage is needed, this voltage does not need to be isolated and often it is not. \$\endgroup\$ – Bimpelrekkie Aug 15 '17 at 17:37
1
\$\begingroup\$

The primary can be any physical location/pin on the transformer and ditto the secondary. The only constraint is that if you expect a decent level of voltage isolation then make sure you use enough "distance" between primary pins along one edge and secondary pins along the same edge. Looking at your picture in detail I'd say this design was good for a 1000 volts: -

enter image description here

Probably the bigger issue would be with the PCB with what is called "tracking" of high voltage PCB traces with low voltage ones.

\$\endgroup\$
  • \$\begingroup\$ Thanks, this makes sense. I wound the primary differently which involved using pin 2 and it jumped from 1 to 2. \$\endgroup\$ – narb08 Aug 15 '17 at 18:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.