ac adapter

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I have an electric dog fence. We had an electrical storm the other
night, and the next day the dog fence was not working. After some
trouble shooting, I determined the problem was fortunately not the
transmitter, but the AC adapter. My wife was going out and I sent her
to Radio Shack with the broken AC adapter and with the mission to look
for a replacement. The old adapter has an output on 12 Volts AC and
200 mA. I told her to look for an exact match, but since I knew that
wasn't likely I told her something will less Voltage or Amperage might
work. Well the fellow at Radio Shack told her I was wrong, and that
less amperage was bad and could damage the transmitter, but more
amperage would be fine. He convinced her to buy an adapter with a 800
mA output. So she brought it home and after being plugged for a
matter of seconds, the transmitter was fried.

I call Radio Shack and the guy insists that the 800 mA should not have
been a problem and it was something else that caused a problem.

Is he right? That doesn't make sense to me. To me more amperage
would a bad thing. But I am not an electrical engineer. So if anyone
could help me out here and tell me who is right, I would appreciate
it.

Thanks

 

[Reinhard Zwirner]

I have an electric dog fence. We had an electrical storm the other
night, and the next day the dog fence was not working. After some
trouble shooting, I determined the problem was fortunately not the
transmitter, but the AC adapter. My wife was going out and I sent her
to Radio Shack with the broken AC adapter and with the mission to look
for a replacement. The old adapter has an output on 12 Volts AC and
200 mA. I told her to look for an exact match, but since I knew that
wasn't likely I told her something will less Voltage or Amperage might
work. Well the fellow at Radio Shack told her I was wrong, and that
less amperage was bad and could damage the transmitter, but more
amperage would be fine. He convinced her to buy an adapter with a 800
mA output. So she brought it home and after being plugged for a
matter of seconds, the transmitter was fried.

I call Radio Shack and the guy insists that the 800 mA should not have
been a problem and it was something else that caused a problem.

Is he right? ...

Yes! The most important thing is that the output voltage of the new
AC adapter is the same as the output voltage of the old one.

The old one could deliver 200 mA; that obviously was sufficient for
the proper operation of the transmitter which draws just the current
it needs.

The new AC adapter is able to deliver 800 mA. That doesn't matter:
your transmitter will still draw the current it needs ...

HTH

Reinhard

 

[CJT]

I have an electric dog fence. We had an electrical storm the other
night, and the next day the dog fence was not working. After some
trouble shooting, I determined the problem was fortunately not the
transmitter, but the AC adapter. My wife was going out and I sent her
to Radio Shack with the broken AC adapter and with the mission to look
for a replacement. The old adapter has an output on 12 Volts AC and
200 mA. I told her to look for an exact match, but since I knew that
wasn't likely I told her something will less Voltage or Amperage might
work. Well the fellow at Radio Shack told her I was wrong, and that
less amperage was bad and could damage the transmitter, but more
amperage would be fine. He convinced her to buy an adapter with a 800
mA output. So she brought it home and after being plugged for a
matter of seconds, the transmitter was fried.

I call Radio Shack and the guy insists that the 800 mA should not have
been a problem and it was something else that caused a problem.

Is he right? That doesn't make sense to me. To me more amperage
would a bad thing. But I am not an electrical engineer. So if anyone
could help me out here and tell me who is right, I would appreciate
it.

Thanks

He seems right to me. Probably what happened is that the storm DID
damage the transmitter and either it or the storm then/also fried the
adapter. The new adapter was more powerful, leaving the transmitter
as the weak link, so it then smoked.