| Electronics > RF, Microwave, Ham Radio |
| Varactor is to a capacitor like {insert unobtanium component} is to an inductor. |
| (1/4) > >> |
| cdev:
What is it I want? Something that changes inductance in response to some control signal or modifiable condition. I want to make a tracking analog RF filter that can be maintained in optimum tune programmatically. |
| ruffy91:
Transductor: An inductor you drive into saturation with a dc current in a second coil so that the inductivity changes. Edit: Also known as magnetic amplifier or mag amp when combined with a transformator. |
| AF6LJ:
--- Quote from: cdev on January 13, 2016, 05:09:35 am ---What is it I want? Something that changes inductance in response to some control signal or modifiable condition. I want to make a tracking analog RF filter that can be maintained in optimum tune programmatically. --- End quote --- A slug tuned coil. Such arrangements have been built, however they are mechanically linked and can become complex. |
| AF6LJ:
--- Quote from: ruffy91 on January 13, 2016, 05:22:04 am ---Transductor: An inductor you drive into saturation with a dc current in a second coil so that the inductivity changes. Edit: Also known as magnetic amplifier or mag amp when combined with a transformator. --- End quote --- I thought of this but never saw anything like this implemented higher than power frequencies or analogue TV sweep frequencies. |
| T3sl4co1l:
They were around for a fairly short time, I think. Frequency range on a transductor is fairly modest, simply because ferrites and powdered irons don't go all that high: maybe into the low 100s of MHz. And it's hard to saturate powdered iron for that frequency range, because its initial mu is so low to begin with. The method works just fine, though. A lot of classic Sony power supplies used resonant converters, where the primary side is a self-excited oscillator, tuned with a saturable reactor and therefore controlling output power. (No controller chip needed whatsoever, just a TL431 on the secondary side.) http://seventransistorlabs.com/Monitor/ Tim |
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