Hi,
I have a project circuit which uses a 220v to 12v 8A transformer for it's power supply.
How much watts will it use up in 220v?
I read that it's watts = V x Amps
So I tried it as 12v x 8A = 96 watts
But when I try it with 220v it becomes
220v x 8A = 1760 watts! I think this is too much power for such a small circuit. So how do I compute for the wattage this device will take up at 220v? Also, I am aware that the 8A is probably the maximum it will go. My circuit will probably take much less, but I can go with the maximum watts computed just to be sure. Thank you.
I have a project circuit which uses a 220v to 12v 8A transformer for it's power supply.
How much watts will it use up in 220v?
I read that it's watts = V x Amps
So I tried it as 12v x 8A = 96 watts
But when I try it with 220v it becomes
220v x 8A = 1760 watts! I think this is too much power for such a small circuit. So how do I compute for the wattage this device will take up at 220v? Also, I am aware that the 8A is probably the maximum it will go. My circuit will probably take much less, but I can go with the maximum watts computed just to be sure. Thank you.
That wattage you’ve calculated is the max the psu will deliver continuously. The actual power consumption depends on the device connected to it.
If the wording on the device says 12v@8A then your first calculation is right. The wattage doesn’t change at another voltage, remember power=voltage*current, so power and current are inversely proportional.
If the wording on the device says 12v@8A then your first calculation is right. The wattage doesn’t change at another voltage, remember power=voltage*current, so power and current are inversely proportional.
The the wattage at the primary will be approximately the same as at the secondary plus losses. Usually with AC circuits the term VA as opposed to watts is used, then hopefully it will become self-explanatory
Oh yeah, it does use 12V 8VA on the transformer instead of just 8A. Is my calculation still correct with 8VA. Yes, the actual power consumption is dependent on the circuit, my impression though is that the circuit cannot take more than what the transformer says it can give. So this should be like the maximum power it will consume.
I hope my understanding is right.
That's arround 100W at the secondary. This power at primary will be around half ampere (100W/220V). As already stated it will depend on the load you'll have.
That approximates to 8 watts
Is that enough for your circuit? If not it won't function properly
An 8VA transformer can probably provide 3W DC continuously to the circuit via a typical PSU.
The circuit will try to take what it needs. If this is more than the transformer is happy to provide then the transformer will overheat and eventually fail.
As others have said, we need to know more in order to help you. Feeding us false information in dribs and drabs is not going to get you very far.
The circuit will try to take what it needs. If this is more than the transformer is happy to provide then the transformer will overheat and eventually fail.
As others have said, we need to know more in order to help you. Feeding us false information in dribs and drabs is not going to get you very far.
220V ??A to 12V 8A
The current will be in inverse proportion to the voltage. That is what a transformer does: exchange voltage and current. It is a "lever". Like a nail-puller. A 10 pound 10 inch pull on the long end makes a 100 pound 1 inch pull on the short end.
12V/220V= 0.0545
8A*0.0545 = 0.436A at 220V
CHECK:
A transformer is (nearly) 100% efficient. Primary and secondary VA should be nearly the same. (Which answers the question you thought you should ask: it is 96VA on both sides.)
12V*8A= 96VA
220V*0.436A= 95.92VA (rounding error)
When the secondary is resistively loaded to a full 8.0 Amps the primary current "should" be 0.436 Amps.
(At this size a transformer may be only 90% efficient so it may really be 107VA primary and 0.485 Amps at 220V.)
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