has anyone ever seen a reference on this???
whats the ratio of the smallest to largest signal a core material can deal with???
1 gauss to 20KG is only what 85 db??? we know 20KG is up at the top, but how low can we go???
You can get an idea by looking at the specs for a high quality line level transformer like the Jensen JT-11-BMCF. At signal levels 40 db below saturation, it's still capable of THD + N distortion approaching 0.001%, or 100db further down than that, and this is more than likely noise limited, not a result of a fundamental limit to the core's resolution. A larger core of a similar material would have correspondingly more domains and thus more dynamic range potential.
First of all, "dB" is a dimensionless (no units, a ratio) quantity, while kilogauss (kg) has units. Equating 20 kg to "86 dB" is valid only if "1.0 gauss" is understood as the reference. As far as dynamic range goes, the noise would have to measured or somehow determined. If the rms noise level is greater than 1.0 gauss, then the dynamic range will be less then 86 dB. A noise "floor" of 2.0 gauss gives a dynamic range of 80 dB, whereas 0.5 gauss of noise gives 92 dB. Does this clarify things? Best regards.
OK assume saturation is 0 db, at what DB value is barkhausen noise, and what is the smallest signal the core can resolve???
-100db, -140db???? and do some cores have better resolution than others???
ahh the old magnetics are really digital approach... i agree, so to rephrase my question, what is the bit depth and sampling rate of various core materials.
i have read a small amount on barkhausen and domain boundries, but have never seen real world numbers applied to it, just acknowledgement that it exists.
also unlike digital, is the barkhausen noise, just a noise floor and is it possible to hear below it???
Reminds me of this posted by Penguin:
The theorethical information content of vinyl is determined by the the highest possible reproducible frequence and the highest possible SN. The highest possible frequecy reproducible is detemined by the minimum radius of the needle and the rotational speed of vinyl. Practical limits exist somewhere around 50-60Khz (remember CD4 records that had a 40Khz carrier signal?) The SN is somwhere around 70-80 dB but it is frequency dependent. The SN determines the number of bits needed to reproduce the signal. Theorethically an LP contains the same amount of information as a digital signal sampled at 120Khz with 13 to 15 bits of resolution. Now would you be able to tell the difference between the analog sound and the digital sound that was sampled around the theorethical numbers? I bet you would, but it puts in perspective the minumum requireemnts to reproduce a signal with a certain SN and HF.
I do not understand:
3. bells = db??
I hope I don't sound condescending:
1) signal: he's just asking how much a transformer core can take at the limits, he doesn't much care if the signal is expressed in volts, power or whatever since he's just looking for the over all back of the envelope limits. He knows that the top limit is similar to a permanent magnet, he's asking where the bottom is.
2) gauss: "The centimeter-gram-second unit of magnetic flux density, equal to one Maxwell per square centimeter." A loudspeaker magnet's strength is on the order of 10000 gauss.
3) http://www.tonmeister.ca/main/textbook/electronics/03.html describes the decibel, in brief:
db = decibel, e.g. 1/10 of a bel
bel is the log bass 10 of a ratio
(often ratios of power are measured as 20*log(p1/p2) instead of 10*log(p1/p2) )
1 gauss over 20 kilogauss = 1/20000
20*log(1/20000)dB = -86dB
I hope this helps a little.
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