Thank you dyamakuchi, I always try to describe complex things in the simplest way - I'm glad it's appreciated.
Good EveningIt's a hydrogen annealing process but the tricky part is the temperature profile (the number of hours at each temperature plateau) so that the crystalline magnetic domains completely randomize in their orientations (think of it as "relaxation"). The temperatures are high enough to make the alloy glow a dull orange. Also, specific additions of minute amounts of molybdenum and chromium to the 80/20 % nickel/iron alloy can result in near-zero magnetic hysteresis (i.e., zero magnetic remanence).
I agree with your stand on absolutism in opinions ... and thank you so much for your very kind words!I dont often find myself quoting people , but I did like the point Jen made here ,
' I'm not saying it should be done always, only pointing out that blanket generalities are stupid as there often exceptions that are meaningful in certain outlier cases. Never say 'never'... say instead, 'most often'. '
There is a tendency to be 'absolutist' at times when we express our opinion , Ive generally evolved my writing style to allow a little 'wiggle room' or not to completely discount people with a diametrically opposed view . It also helps prevent Trolls getting their teeth into to you , and makes them a little easier to shake off if needs be .
I have a pdf version of one of Bills transformer books here somewhere , I must dig it out again .
I think its not overstating it to say on behalf of our group to Bill , you do us a great honour sir , bringing your presence and knowledge to GDIY.
There's very little litt on the subject. It seems to be transmitted orally if you know the secret handshake .found some more links
I am looking for information on pilgrim stepwound. Anyone have a good link on this winding method?
Sectioning xfmrs was a usual technique when radio was less than a few 100's kHz.I have a few very old English made audio transformers from the 1920's , a Marconi pi wound unit where the bobbin is divided into many side by side sections
I wished it could "null". It just balances them for CMRR trimming.Another thing I'd been meaning to ask was about the use of a trimmer cap to nul the stray capacitance across transformer sections
I can't see the point, since normal operation will demag the xfmr.Off topic a bit but I recently saw, a tube heater scheme iirc, and it had a diode hanging off one of the transformer terminals. Said something about helping to keep the transformer from magnetizing.
That would be interesting. Maybe an occasion to discover something, or commiserating with people who find solutions to non-existing problems...I can't find where I saw it.
lol...That would be interesting. Maybe an occasion to discover something, or commiserating with people who find solutions to non-existing problems...
That is true, and for a long time I have taken this point in consideration and made sure LED's didn't receive significant reverse voltage. However, one day I decided to experiment and found out that with the standard 6.3Vac voltage I didn't need any protection, with the LED's I had at hand. In any commercial product, I wouldn't take any risk, though. It may be there is a cumulative effect that reduces the life span of LED's. I don't remember having seen any thorough litt about the effects of reverse voltage on LED'slol...
I found it. Was Merlin's page on heaters as it related to using leds from the heater supply.
"Traditionally, an indicator lamp was often run off the heater supply too. These days we can use LEDs. However, LEDs are not built to withstand much reverse voltage
In this instance it's the magnetizing current in operation. It shifts the magnetizing curve. The effects of this unbalance must be put in perspective with the nominal transformer power. Again if we're talking about 10-20 mA drawn from a 6.3V winding, it's about 1/1 000th of the nominal power of a typical tube amp. It's not more significant than the very common practice of using single-wave rectification for creating the bias voltage., so it is a good idea to put a diode (or another LED) in anti-parallel with an LED on an AC supply. This diverts reverse current around the LED and keeps the reverse voltage across it to one diode drop (and it also reduces DC magnetisation in the transformer)"
Enter your email address to join: