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Registered Member #1656
Joined: Wed Aug 27 2008, 03:28PM
Location: Pittsburgh PA
Posts: 53
Dumb question, but one I couldn't find a definite answer on. I am working on another audio modulated flyback, and the mosfet used is an IRFP250N. My question is, could i use an IRFP450 instead?
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374
It looks like the circuit relies on a slowed-down turn-off of the mosfet. A more reasonable approach would be to add a capacitor across the source and drain tabs to control the inductive peak. You might end up killing mosfets with low gate capacity with this ciruit. Once you have the (drain!) voltage swing under control, almost any mosfet you can drive with the oscillator output will do. The IRFP450 may be a suitable replacement but look over the schematic before actually building it. Even TVS diodes / VDRs / RC-Snubbers won't hurt. I suggest you add a 400V TVS diode to the IRFP450 as an olfactory overvoltage sensor
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
" audio modulated flyback- "
Why not modulate the flyback like this?-- wrap 3 turns around the core one way and another 3 on the otherside in series opposing. Connect these to the speakler terminals of an audio amp with a 0.01 uf cap in parallel,
This is an old technique known as an increductor. It was used to modulate an oscillating ferrite core and worked very well with 60 Hz modulating. Perchance it will cause mixing (modulation) of the drive rate with the audio.
Registered Member #1656
Joined: Wed Aug 27 2008, 03:28PM
Location: Pittsburgh PA
Posts: 53
radiotech wrote ...
" audio modulated flyback- "
Why not modulate the flyback like this?-- wrap 3 turns around the core one way and another 3 on the otherside in series opposing. Connect these to the speakler terminals of an audio amp with a 0.01 uf cap in parallel,
This is an old technique known as an increductor. It was used to modulate an oscillating ferrite core and worked very well with 60 Hz modulating. Perchance it will cause mixing (modulation) of the drive rate with the audio.
Wow, crazy, i never heard of that before. Do you have a link or diagram by chance?
Ok. the IRFP450 worked as far as turning it on, But i still get o audio. Everything is to spec to the diagram. *is getting a headache*
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Audio modulated LOPT/FB
