My parents had a Fisher console stereo that survived my older sister. I knew it was a good stereo system because of this. She would play stacks of record LPs day after day, and then it survived me. Tube stereo with EL84 output tubes and iron that survived numerous heating and cooling cycles.
My KX-200 survives to live another day, despite being cycling hot and cold, day after day, year after year since the 1960s.
My KX-200 survives to live another day, despite being cycling hot and cold, day after day, year after year since the 1960s.
cogitech,
Thanks for posting that link!
I copied the following statement from the link you provided:
"Transformer Current Ratings: A transformer's A.C. current rating needs to be recalculated from the D.C. load current. The required current varies with type of rectifier chosen and filter type. Use the formulas below as a guide, shown for common D.C. supplies. Included in the formulas higher peak to peak capacitor charging current in the filter".
The rest of the document has schematics that shows the ratio of the transformer AC current rating, versus the same transformer DC rating.
It shows the connection; rectifier configuration; 1/2 wave or full wave; and the Load (Resistor load, or filter load: L input or C input).
Full Wave Bridge Capacitor Input Load:
I D.C. = 0.62 X Sec. I A.C.
That means a transformer with an AC current rating of 1A will safely put out 0.62A DC.
In other words, you need a 1.61 AC current rated transformer to put out 1A DC.
Full Wave Bridge Choke Input Load:
I D.C. = 0.94 X Sec. I A.C.
That means a transformer with an AC current rating of 1A will safely put out 0.94A DC.
In other words, you need a 1.06 AC current rated transformer to put out 1A DC.
Thanks for posting that link!
I copied the following statement from the link you provided:
"Transformer Current Ratings: A transformer's A.C. current rating needs to be recalculated from the D.C. load current. The required current varies with type of rectifier chosen and filter type. Use the formulas below as a guide, shown for common D.C. supplies. Included in the formulas higher peak to peak capacitor charging current in the filter".
The rest of the document has schematics that shows the ratio of the transformer AC current rating, versus the same transformer DC rating.
It shows the connection; rectifier configuration; 1/2 wave or full wave; and the Load (Resistor load, or filter load: L input or C input).
Full Wave Bridge Capacitor Input Load:
I D.C. = 0.62 X Sec. I A.C.
That means a transformer with an AC current rating of 1A will safely put out 0.62A DC.
In other words, you need a 1.61 AC current rated transformer to put out 1A DC.
Full Wave Bridge Choke Input Load:
I D.C. = 0.94 X Sec. I A.C.
That means a transformer with an AC current rating of 1A will safely put out 0.94A DC.
In other words, you need a 1.06 AC current rated transformer to put out 1A DC.
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They should write it the way you did, rather than beating around the bush. It wasn't immediately obvious what they were getting at. In fact, I interpreted it exactly the opposite way.
cogitech,
I had the same problem interpreting it.
For cap input filters:
Instead of using 1.61 multiplied times DC to get the required AC current rating, I often use 1.8 or 2.0 multipliers as a general rule.
Just makes things run cooler. Especially because I use solid state rectifiers. And if you have to increase the output tube quiescent current,
you have some margin to do that.
Whenever I can, I use choke input filters. The transformers really like that, and run cool.
I use solid stage diodes.
But if you want to use tube rectifiers, they really love choke input, the peak currents are so much lower for the same DC current load.
And that means the rectifier voltage drop is a little less, than it would be with cap input filters.
Chokes cost more, chokes spray magnetic fields, chokes take up room, chokes are heavy, and require higher B+secondary voltage to get the correct DC B+ Voltage, but even with all that, choke input is my preference.
I had the same problem interpreting it.
For cap input filters:
Instead of using 1.61 multiplied times DC to get the required AC current rating, I often use 1.8 or 2.0 multipliers as a general rule.
Just makes things run cooler. Especially because I use solid state rectifiers. And if you have to increase the output tube quiescent current,
you have some margin to do that.
Whenever I can, I use choke input filters. The transformers really like that, and run cool.
I use solid stage diodes.
But if you want to use tube rectifiers, they really love choke input, the peak currents are so much lower for the same DC current load.
And that means the rectifier voltage drop is a little less, than it would be with cap input filters.
Chokes cost more, chokes spray magnetic fields, chokes take up room, chokes are heavy, and require higher B+secondary voltage to get the correct DC B+ Voltage, but even with all that, choke input is my preference.
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I agree. My Tubelab SSE has a choke input filter and I wish I had room to retrofit one into my P-P EL34 amp - but there is just no way unless I bolt it to the side of the chassis.
I an known for running my stuff hot, Those temps seem fine to me. If it's under 100C, it's probably alright. I have an SE MOSFET amp that reaches 95C heatsink temperature, and that's within spec, too. Even the latest CPU designs are running at almost 100C now.
> Even the latest CPU designs are running at almost 100C now.
2009 ThinkPad T400, fan quit. Will email or surf all night but 45 minutes of ZOOM and it shuts down. Discovered this CPU is rated 105 deg C. Got a newer T400 coming but caught in the ice in PA/NY/CT area.
2009 ThinkPad T400, fan quit. Will email or surf all night but 45 minutes of ZOOM and it shuts down. Discovered this CPU is rated 105 deg C. Got a newer T400 coming but caught in the ice in PA/NY/CT area.
I'm taking sauna's twice a week at 95° C 🙂
I can't find my spec sheet right now, but I think it's actually good for the lifespan of my parts 😀
The idea of taking a sauna at 95 Degrees C, almost makes me Boil.
Just 5 Degrees C short of boiling water.
The definition of 95 Degrees C is not boiling.
The proper definition of that temperature on the body, is burn.
Just 5 Degrees C short of boiling water.
The definition of 95 Degrees C is not boiling.
The proper definition of that temperature on the body, is burn.
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I believe they are measuring the sauna at the point of the boiling water.
Or, maybe the thermometer is out in the open, measuring the steam.
When the water escapes as steam, and the sauna enclosure is not perfectly air tight, the steam looses energy (cools).
If we perfectly seal the enclosure, we can raise the temperature to create a higher boiling point.
Likewise, If we are at 3000 Meters altitude and air pressure, we lower the temperature to a lower boiling point.
Of course the steam looses energy when it contacts your skin too.
If it did not cool off, then it transferred no energy to your skin.
But to each his own sauna.
Or, maybe the thermometer is out in the open, measuring the steam.
When the water escapes as steam, and the sauna enclosure is not perfectly air tight, the steam looses energy (cools).
If we perfectly seal the enclosure, we can raise the temperature to create a higher boiling point.
Likewise, If we are at 3000 Meters altitude and air pressure, we lower the temperature to a lower boiling point.
Of course the steam looses energy when it contacts your skin too.
If it did not cool off, then it transferred no energy to your skin.
But to each his own sauna.
Try being in a race car for a couple hours at 120 f plus and your right foot and leg cooking from the transmission tunnel. .
You can sweat out some toxins ...
You can sweat out some toxins ...
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oldtimers seldom see traffo heating as an issue, the newcomers do....
but wanting a power traffo that does not heat up much is not an impossible thing, you just have to pay extra for it...
using M6 silicon and running the traffo at lower flux density can make the traffo run cooler, in other words, oversizing it...i take this into first consideration in all my traffo builds, "build it like a tank" says PRR, but within reason of course....
but wanting a power traffo that does not heat up much is not an impossible thing, you just have to pay extra for it...
using M6 silicon and running the traffo at lower flux density can make the traffo run cooler, in other words, oversizing it...i take this into first consideration in all my traffo builds, "build it like a tank" says PRR, but within reason of course....
A transformer can also heat up if the load is not in ballance (in case the transformer has a center tap) or a single diode is used or a dc voltage is applied on it (and dc current flows).
A transformer can also get hot doing F all. Just plugging in a transformer without a load will heat it sometimes.
220°F is a nice temperature for a sauna 🙂 Depending on the size. If it's a bigger sauna with more space and air it's nice, if it's a smaller one it feels hotter and maybe not so nice. YMMV.
Thermometer is hanging on the wall, away from the stove, measuring air temp. There's no steam, we are talking dry Finnish sauna
, not wet Turkish steam baths or Russian Banya 
transformer heating is of the following; hysteresis loss wing to the weight of core and grade of steel used and flux density, eddy current loss owing to the thickness of laminations and surface insulations...
there is another source of heating, the rectification process distorted the secondary currents contributing to heating the core by 30% from what i gleaned from technical writings...
nature of the beast.......
there is another source of heating, the rectification process distorted the secondary currents contributing to heating the core by 30% from what i gleaned from technical writings...
nature of the beast.......