philba
New Member
I'm planning to build an inverter to drive electro luminescent wire. Now before you all shout "buy one, they are way cheap", I am looking to experiment with frequency and voltage. In addition, I want to experiment with some ideas that require more control over the voltage going to the EL wire. I've got lots of of those cheap inverters.
So, first the requirements:
- runs off 3V
- frequency from 400hz to 4Khz
- max 50 mA on output side, probably more like 10 mA
- output voltage initially at 100V. intertested in varying up to 150V (see below)
I'll probably wind my own transformer(s) which is the main area I have questions on. I am pretty clueless about magnetics. To start with, I'm planning on using essentially a multivibrator circuit to drive alternate halves of a CT primary on the transformer. The secondary would deliver the 100-150V AC to the EL wire. Does this make sense to you all? Is there a better circuit that i should use and still be able to vary the frequency? I have seen some designs with a feedback coil tbut that seems to lock in the frequency and I have no idea how to determine that anyway. Most of the transformer pages I've found deal with 60 hz so the first question is what are the implications of my frequency range (400 to 4K)? Should I just follow the cookbook approaches for 60 hz stuff and not worry about efficiency? What are the best cores for those frequencies? what about a toroid? I see them all the time in the surplus catalogs though they seldom say the material. I did find several audio transformer winding pages that may be applicable so I will spend a bit more time there - of course it's audio focused so I need to figure out what isn't applicable.
on varying the output, is using a variac to control the voltage a hair-brained idea? I don't know if it will work at 4Khz.
Finally, is there any free simulation software for transformer design? most of what I've found via google is not free (and not cheap, either). I'd like to try different core materials and see how they might perform.
So, first the requirements:
- runs off 3V
- frequency from 400hz to 4Khz
- max 50 mA on output side, probably more like 10 mA
- output voltage initially at 100V. intertested in varying up to 150V (see below)
I'll probably wind my own transformer(s) which is the main area I have questions on. I am pretty clueless about magnetics. To start with, I'm planning on using essentially a multivibrator circuit to drive alternate halves of a CT primary on the transformer. The secondary would deliver the 100-150V AC to the EL wire. Does this make sense to you all? Is there a better circuit that i should use and still be able to vary the frequency? I have seen some designs with a feedback coil tbut that seems to lock in the frequency and I have no idea how to determine that anyway. Most of the transformer pages I've found deal with 60 hz so the first question is what are the implications of my frequency range (400 to 4K)? Should I just follow the cookbook approaches for 60 hz stuff and not worry about efficiency? What are the best cores for those frequencies? what about a toroid? I see them all the time in the surplus catalogs though they seldom say the material. I did find several audio transformer winding pages that may be applicable so I will spend a bit more time there - of course it's audio focused so I need to figure out what isn't applicable.
on varying the output, is using a variac to control the voltage a hair-brained idea? I don't know if it will work at 4Khz.
Finally, is there any free simulation software for transformer design? most of what I've found via google is not free (and not cheap, either). I'd like to try different core materials and see how they might perform.
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