[radicooldude]

I have salvaged a transformer from my 13" Portable TV/VCR (Those old kinds, with the tubes, that will run on D batteries and good for van trips), and I took out the transformer and it is rather large. About 3.5" diameter, and about 2-3lbs. On the back of the TV it said input 120v, 75w, and input 12v dc (for when it runs off batteries). Is there a way to find out how much amps this thing will put out? I assume this will make 12v DC, as the TV will run on 12v dc.

So, if 120v input, 12v DC out, and 75w, is there a way to find amperage? Thanks - Zachery

[pastera]

a few milliamps at high voltage - it's the flyback transformer used to generate the 2nd anode voltage.

Aaron

[b_cybe]

For starters you should be carefull when working with TV's. Specially on old TV's there can be a good dose of radioation (kinda X-ray) in the plate back in the TV (Normally there is a metal plate back at the TV to absorb these radioations so that under normal use nothing is let out. But if you open up you can be exposed. There is also enough current and voltage to kill you. I dont know how much you know about TV's, perconally I dont work anything with TV's but these were the genreal guidelines i learned.

Secondly I would be VERY carefull with that power supply of yours, normaly a TV use a step up coupling (dont remember the correct word in english, the post before say flyback transformator but I dont remember the word anymore) to "generate" the necesary volts (ca. 10000V for a normal tube in europe atleast..). Eaven thought it only have 9 volts on the input doesn't in this case mean that 9V will come out. Usually the TV used a coupling of several capasitors and diodes to get the high voltage necessary to light the tube. A general TV tube will not light with 12V. You could remove the step up part of the circuit, but you must find it and you most have some experience with electronics so that you are sure you are not hurt.

[radicooldude]

I understood that there were x-ray radiation in the tv, so I took out the transformer carefully. This is a tiny tv, so it probably isn't worth using..I'll just throw it out. I just opened the case, and unscrewed the transformer and popped off the two jumper cables connected to it. Hopefully I didnt do anything harmfull. Thank for the warning though. - Zachery

[Al_The_Man]

I understood that there were x-ray radiation in the tv, so I took out the transformer carefully.

Did you wear a lead suit
Actually there is no radiation when the set is off and has been off for a while, the electro-magnetic radiation is from the HOT Horizontal Output Transformer, refered to as a flyback, is only when the set is running.
This Txfr can be identified by its construction, made from a large ferrite loop mounted next to a rectifier tube with a connector on top.
The connection on the side of the crt can store a charge for some time, but if it has been off for a while there should be no danger.
If the transformer you are looking at has steel laminations or steel cover, then it will be a mains transformer 50/60hz.
This one may be salvaged, but is probabally fairly low current.
Al.

[b_cybe]

Did you wear a lead suit
Actually there is no radiation when the set is off and has been off for a while, the electro-magnetic radiation is from the HOT Horizontal Output Transformer, refered to as a flyback, is only when the set is running.
This Txfr can be identified by its construction, made from a large ferrite loop mounted next to a rectifier tube with a connector on top.
The connection on the side of the crt can store a charge for some time, but if it has been off for a while there should be no danger.
If the transformer you are looking at has steel laminations or steel cover, then it will be a mains transformer 50/60hz.
This one may be salvaged, but is probabally fairly low current.
Al.

Ok, I learned that old TV's could store some of the radioation, though myself I haven't too much experience repairing/savaging TV's.

[Al_The_Man]

Ok, I learned that old TV's could store some of the radioation, .

I think most people that refer to that mean the large DC charge that is stored on the Anode of the CRT.
BTW in a modern colour set, the anode voltage can run around 30k volts. This charge can take up to days before it decays completely.
The high energy that an old set would radiate when running is a frequency around 15k hz.
Al.

[keebler303]

if you had a transformer with no losses then power in =power out. so that 75 watts at 12VDC would be 6.25A

[radicooldude]

This tv has been open, cracked in half at where the case comes apart for about 3 years. I must have taken out the transformer, not the flyback one, as this one has steel.