Has anyone put the transformer inside the microphone body ? Fed with an AC wall wort the isolated power could then be stepped up inside the mic rather than having to have to make a choice between lunch box with your tube mic or fets giving you power and awaiting the day they make magic blue smoke. I've wanted to get the time to build this for a while, the core has been with me wound for 2 years without getting strung with wire and tested.
I had to relearn transformer theory and then learn it proper. It got glossed over in computer engineering but not in any depth needed to make them. Transformers are wound to turns per volt, ratio is just a side effect of those turns. The calculations for figuring out that number were a pain to find again and a bigger pain to learn to wield correctly.
Adding to that I chose an R core transformer as the topography, my r core is exactly the same way the U47 mic audio transformer is wound except with a strip of metal rather than stacked laminations. So for my Power Supply I choose to learn to wind it in the most complex "german" way possible and I figured this out only after mastering it because with no master to teach me and unreliable and conflicting internet data, I had no way of knowing I was trying to eat the elephant, tusks first. Years ago I had seen the connections for the U47 and thought it insane, last week as I finished calibrating and figured out core polarity, I happened to see the U47 diagram again and I smacked my head...
I'm using a high nickel, grain oriented strip insulated with kapton tape on one side and wound to create an 8mm square core. At these sizes the effect of the gap of a round tube on a square peg isn't zero but it's not significant, consider the tiny gaps you see are smaller than the thickness of a normal plastic transformer winding bobbin, I have Several transformers as examples. The idea was to make my own tube mics from scratch so the transformer steel was for audio but it does just fine in a power application.
This is round 2, round one wasn't even close to core saturation, pie in the sky internet R core numbers. This is the rewind with different numbers to let me do AC injection for getting data on the strip winding. The filament is a good load for the transformer and isn't at full power yet. It didn't need to be, just needed to be a reliable load to test the core saturation voltage and calculate my proper turns per volt.
I'm shrinking it to the smaller core with 3d printed bobbins. Once it's done I'll have a rought prototype to base minor winding updates on and maybe even find some prolific builder who could test in rapidly.
In addition to selling my own mics with em the goal is to tap the transformer for heater, bias and then 6 or 7 taps for various tubes, start at 100v and tap it every 50v out to 300. Pair it with a tested, CSA approved power brick and a matching barrel jack that people can use in their mic or small desktop amp design.
People have mics bigger than oldschool maglights, there is ample room to have the high voltage all onboard and increase safety by double isolating the transformer and having all HV happen inside the grounded metal case.
I had to relearn transformer theory and then learn it proper. It got glossed over in computer engineering but not in any depth needed to make them. Transformers are wound to turns per volt, ratio is just a side effect of those turns. The calculations for figuring out that number were a pain to find again and a bigger pain to learn to wield correctly.
Adding to that I chose an R core transformer as the topography, my r core is exactly the same way the U47 mic audio transformer is wound except with a strip of metal rather than stacked laminations. So for my Power Supply I choose to learn to wind it in the most complex "german" way possible and I figured this out only after mastering it because with no master to teach me and unreliable and conflicting internet data, I had no way of knowing I was trying to eat the elephant, tusks first. Years ago I had seen the connections for the U47 and thought it insane, last week as I finished calibrating and figured out core polarity, I happened to see the U47 diagram again and I smacked my head...
I'm using a high nickel, grain oriented strip insulated with kapton tape on one side and wound to create an 8mm square core. At these sizes the effect of the gap of a round tube on a square peg isn't zero but it's not significant, consider the tiny gaps you see are smaller than the thickness of a normal plastic transformer winding bobbin, I have Several transformers as examples. The idea was to make my own tube mics from scratch so the transformer steel was for audio but it does just fine in a power application.
This is round 2, round one wasn't even close to core saturation, pie in the sky internet R core numbers. This is the rewind with different numbers to let me do AC injection for getting data on the strip winding. The filament is a good load for the transformer and isn't at full power yet. It didn't need to be, just needed to be a reliable load to test the core saturation voltage and calculate my proper turns per volt.
I'm shrinking it to the smaller core with 3d printed bobbins. Once it's done I'll have a rought prototype to base minor winding updates on and maybe even find some prolific builder who could test in rapidly.
In addition to selling my own mics with em the goal is to tap the transformer for heater, bias and then 6 or 7 taps for various tubes, start at 100v and tap it every 50v out to 300. Pair it with a tested, CSA approved power brick and a matching barrel jack that people can use in their mic or small desktop amp design.
People have mics bigger than oldschool maglights, there is ample room to have the high voltage all onboard and increase safety by double isolating the transformer and having all HV happen inside the grounded metal case.
There isn't a single DIY transformer article I can easily find here, you can buy the strip steel and insulation on amazon now 8mm square winding works out to 0.02401 turns per volt. This place needs a DIY transformer article, especially in small scale they are easy to make with current supply chains.
Sorry but you got your equation upside down.
A 0.64 mm² core needs 70 turns per Volt at 50 Hz if made out of Silicon Steel.
A high permeability alloy will reduce that, but still to some comparable value.
As of:
In any case, for basic power transformers all you need to know is:
N_0 (turns for 1V) is 45/S in cm²
and keep current density at 2A/cm² .
You can do fancier Math any day of the week but that is the basic stuff.
Oh, and keep power in VA at S² tops, even better if you derate that by 30-50%
Not MUCH more than that.
A 0.64 mm² core needs 70 turns per Volt at 50 Hz if made out of Silicon Steel.
A high permeability alloy will reduce that, but still to some comparable value.
As of:
I am surprised there is none, you sure?
In any case, for basic power transformers all you need to know is:
N_0 (turns for 1V) is 45/S in cm²
and keep current density at 2A/cm² .
You can do fancier Math any day of the week but that is the basic stuff.
Oh, and keep power in VA at S² tops, even better if you derate that by 30-50%
Not MUCH more than that.
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