Replacement Transformer Question
#1
Replacement Transformer Question
A desk lamp stopped working and it appears the transformer failed. It's about12 years old.
INPUT: AC 120V 60Hz 0.46A
OUTPUT: AC 12V
50W max (bulb I assume)
The replacement transformers I find are all rated in milliamps on the secondary, so how big a transformer do I need?
Another transformer (different project) I have is rated at 120VAC and 9.5W on the primary, and 12VDC and 500mA on the secondary.
I can't get the numbers to add up. Someone please refresh my memory.
Thanks.
INPUT: AC 120V 60Hz 0.46A
OUTPUT: AC 12V
50W max (bulb I assume)
The replacement transformers I find are all rated in milliamps on the secondary, so how big a transformer do I need?
Another transformer (different project) I have is rated at 120VAC and 9.5W on the primary, and 12VDC and 500mA on the secondary.
I can't get the numbers to add up. Someone please refresh my memory.
Thanks.
#2
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maybe this will help.
120v / 12v = 10 ratio
10 x 0.46A = 4.6 amps secondary
4.6 amps x 12 volts = 55.2 watt
50 watts / 12 volts = 4.16 amps
You need about a 5amp transformer on the secondary output
5 amps x 12 volts = 60 watts.
0.46A = 460 milliamps
500 milliamps = 1/2 amp. = 0.5A
1000 ma = 1 amp.
120v / 12v = 10 ratio
10 x 0.46A = 4.6 amps secondary
4.6 amps x 12 volts = 55.2 watt
50 watts / 12 volts = 4.16 amps
You need about a 5amp transformer on the secondary output
5 amps x 12 volts = 60 watts.
0.46A = 460 milliamps
500 milliamps = 1/2 amp. = 0.5A
1000 ma = 1 amp.
#4
Originally Posted by John Nelson
Unless you just love this lamp, a new lamp may be cheaper than a new transformer.
#5
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I agree the size is small for 5 amps
I think your bulb may have been 12 volts at 10 watts
using a 50 watt bulb would take out the transformer.
or its a 24 volt bulb
or a switching power supply.
If your sure the transformer is bad. try unwrapping the tape on the transformer look for a break in the wire.
most of the time the break is close to the leads soldered to the transformer.
I think your bulb may have been 12 volts at 10 watts
using a 50 watt bulb would take out the transformer.
or its a 24 volt bulb
or a switching power supply.
If your sure the transformer is bad. try unwrapping the tape on the transformer look for a break in the wire.
most of the time the break is close to the leads soldered to the transformer.