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I'm trying to buy components for these simple capacitor chargers but I don't know how to find the transformers. I've looked all over Mouser and other websites but their specifications are confusing and I can only find huge 110V-24V type transformers.

  • Are these called flyback transformers, or maybe audio transformers?
  • What is the ratio? I'm guessing that's 6 turns to 1750 turns.
  • What is the #25 and #45?

I would really appreciate the help, I just need a simple camera flash circuit for a project. Also, how would I calculate a different transformer if I wanted 5V input and 300V output?

I'm really running out of time with this project.

enter image description here enter image description here

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    \$\begingroup\$ Welcome to EE.SE! It’s most likely custom. ”I just need a simple camera flash circuit for a project.” My advice would be to buy a circuit ready made for the purpose. \$\endgroup\$
    – winny
    Nov 2 '20 at 19:26
  • \$\begingroup\$ Thanks, but part of the project is sourcing all the components and making it myself. Is there a similar common transformer I could use? \$\endgroup\$
    – Mac D.
    Nov 2 '20 at 19:30
  • \$\begingroup\$ Probably yes. Try to find an evaluation kit for the purpose and see if they list an “off the shelf” transformer from some manufacturer, probably Wurth or Bourns. You’ll end up paying a premium for the service if having it all thought out for you, but if your production volume is low, this still makes sense. Otherwise get it made for you. MOQ is usually very low. \$\endgroup\$
    – winny
    Nov 2 '20 at 19:34
  • \$\begingroup\$ So is the principal of that transformer to convert 1.5v to 350v or does it operate more like a boost converter, where the transistor is collapsing the magnetic field over and over again and charging the capacitor? Because in that case, the ratio could probably be much smaller right? \$\endgroup\$
    – Mac D.
    Nov 2 '20 at 19:37
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    \$\begingroup\$ Pretry much, but bear in mind that flyback transformer calculations are far more involved than regular 50/60 Hz transformers. \$\endgroup\$
    – winny
    Nov 2 '20 at 20:27
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Get a ferrite pot core and wind the transformer yourself. There is zero chance of reliably finding these transformers from the tens of thousand custom transformers available and, there is only moderate likelihood that one of those tens of thousand might be the one shown in your picture.

The # numbers are likely to be SWG gauges (rather than AWG wire gauges): -

  • #45 = SWG 45 = 0.0711 mm diameter
  • #25 = SWG 25 = 0.508 mm diameter

Table: -

enter image description here

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  • \$\begingroup\$ Okay, but could you just explain the principal of the circuit? I don't necessarily need that exact transformer or voltage output, I just want to understand the principle so I can make one myself if need be. Thank you! \$\endgroup\$
    – Mac D.
    Nov 2 '20 at 19:41
  • \$\begingroup\$ Like does the transformer really have a 1:233 ratio or is it similar to a boost converter where it might have a much lower ratio, but the transistor is helping to collapse the magnetic field and store it in the capacitor \$\endgroup\$
    – Mac D.
    Nov 2 '20 at 19:44
  • \$\begingroup\$ @MacD. it has 1:292 turns ratio not 1:233. It's an oscillator. \$\endgroup\$
    – Andy aka
    Nov 2 '20 at 20:20
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You might be able to salvage such a transformer from an old LCD panel that uses a cold-cathode fluorescent (CCFL) inverter. Or, from an old photoflash unit.

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