[Russ Arcuri]

Hi all,

One of my amps is a buffered CMoy in an Altoids tin. It's one of these:

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=5823354949

Yesterday I walked in on my son playing with it. He had the input jack connected to the output jack. I immediately unplugged the cable, but best as I can figure out, he had it connected that way for about 5-10 seconds.

The on/off switch is triggered automatically when a cable is plugged into the output jack. There is no built-in volume control, as it's intended to be used with portable players with their own volume controls.

I'm thinking this caused an electronic feeback loop, and that it might have been dangerous for the electronics. However, the amp now works like it always did. So the question is, how likely is it that some damage was done, given that it seems to be working fine? Can connecting the input to the output cause damage in 5-10 seconds?

 

[rickcr42]

All you did was turn the amp into a unity gain buffer briefly,No damage

 

[Russ Arcuri]

Thanks for the reply, Rick. For the record, it was my son that connected the input to the output, not me. My initial thought was that he might have damaged it. I was not happy.

 

[rickcr42]

Quote:

Thanks for the reply, Rick. For the record, it was my son that connected the input to the output, not me. My initial thought was that he might have damaged it. I was not happy.

Have three "minimees" so i know these things not only can happen but more often than not do.Mine are now all grown (youngest is 16) so now I have to only deal with my tools being "lost in space" (not me dad !

)

the way an opamp works is it has a HUGE amount of open loop gain which we use to set the final gain with the Rg/Rf resistors to close up the loop.Straight wire from output to input cancles out all gain at the "-" terminal so you end up with "zero" gain or a gain of slightly less than 1
Even when if fed back to the "+" input the absolute worst you can do is turn the amp into an oscillator but since there are no headphones connected no harm done unless left to "oscillate" for hours and even then it would be rare to do any real harm (heat damage from a full power continous surge) other than to your battery life/wallet for replacements

So plug 'er in and let 'er rip (and you can let the boy out of the basement now

)