I think we are all over simplifying, by assuming sinusoidal currrent output of the transformer, when its nothing like this. And the load is more like switching a short then anything else.
If
is true than a small transformer should handle the short high current output bursts needed to charge the power caps.
If
is true than a small transformer should handle the short high current output bursts needed to charge the power caps.
No, there isn't any assumption of sinusoidal currents or voltages.
You forgot the "until the windings melt" part.
The wire is heated by the current that flows through it. Power loss is proportional to the square of RMS current.
RMS current is higher for the peaky current waveform drawn by a rectifier than for a resistive load at the same active power consumption.
That's why a 1500VA transformer may only be able to provide ~1000W of active power without overheating.
You forgot the "until the windings melt" part.
The wire is heated by the current that flows through it. Power loss is proportional to the square of RMS current.
RMS current is higher for the peaky current waveform drawn by a rectifier than for a resistive load at the same active power consumption.
That's why a 1500VA transformer may only be able to provide ~1000W of active power without overheating.
yes, the transformer manufacturers usually recommend that the VA rating be reduced to ~70% when feeding a capacitor input filter.
Then the DC output voltage is ~40% higher, that requires the DC current to be reduced to maintain the same maximum power from the transformer.
The net effect, is that the maximum continuous DC current from the output of the capacitor input filter is ~ 50% of the AC current rating of the transformer.
Then the DC output voltage is ~40% higher, that requires the DC current to be reduced to maintain the same maximum power from the transformer.
The net effect, is that the maximum continuous DC current from the output of the capacitor input filter is ~ 50% of the AC current rating of the transformer.
cbdb said:
Answered Earlier...
megajocke said:
Is it me or this guy is asking questions that already have been answered ??
ANYWAYS 🙄
A little bit more on topic, I should have all the boards on friday and hopefully the power supply boards as well along with the rest of the parts so i can put the 2 power supply's together along with the cap bridging network between then 2.
Next on the list Digi-Key parts order and to figure out the cooling...
Forced Air Or Liquid ???
Liquid cooled amplifier...
Wouldn't that be a bit impractical?
Don't you think forced air cooling will be enough? 🙂
Wouldn't that be a bit impractical?
Don't you think forced air cooling will be enough? 🙂
megajocke said:Liquid cooled amplifier...
Wouldn't that be a bit impractical?
Don't you think forced air cooling will be enough? 🙂
I have a lot of stuff left over from damaged shipment of koolance cases 😉
i got 2 of these and a Controler/Reservoir for a Pc i was going to build, but never happened.
And a custom heat sink from 2 x 1/2-7/8" thick plate of copper would be a premium 😛
PS...
Plenty of stuff is offered and drafted from the computer world with enough imagination...
Look Here
Adrculda said:
Next on the list Digi-Key parts order and to figure out the cooling...
Forced Air Or Liquid ???
How about liquid air?
Steve Dunlap said:
Good idea !!!
i can make it liquid nitrogen cooled
and then it can be a smoke machine too !!
I swear...
Sometimes people come up with the dumbest **** !!! 🙄 🙄 🙄
I ask the same questions becuase I dont really get answers. Big transformers are cooled.
Its just not practical to cool smaller ones or they would. Cooling the wires will increase the available average power output(power out before smoke), no?
Yes, big utility trafos are cooled - with oil. The stuff that works is highly toxic. 10W-30 will *work*, but not as effectively. Airflow over a standard toriod will keep its temp down, but since the radiating surfce is relatively small you only get limited benefit. It can't hurt, but don't expect over a 20% increase in current capacity at the same temp rise.
cbdb said:
Ok...
Shall we try this again...
the size is a big thing as a lot of transformers take up a lot of space and weight as well, and by adding any sort of cooling it will add more weight and take up more space for a small gain.
Secondly the inputs is inversely proportional to the output, and in order to have a larger output you need a larger input where you are limited by your wall socket.
Earlier on in my post i was planning to go with a very large toroid, but other have noted, it would be way too large and heavy as well to move around and also would have very large inrush current during start up not to mention the rather LARGE cabling will be needed to feed the power hungry monster.
its the weight of the copper that really adds up. The core is not as heavy as the primary and secondary put together !
amplifier
hi wg ski
greetings seen your schematics post 118 would like to try it
which circuit would be easier to build cascode or post 118 are high
and low slide switches necessary can you tell me the function of
the high and low switches
thanking you
andrew lebon
hi wg ski
greetings seen your schematics post 118 would like to try it
which circuit would be easier to build cascode or post 118 are high
and low slide switches necessary can you tell me the function of
the high and low switches
thanking you
andrew lebon
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