Led indicator in solid state amps

Tube or solid-state, this section goes to eleven!

Led indicator in solid state amps

Postby phase396 » 06 Mar 2019, 20:34

Hello everyone. I have a pretty simple question. After looking at a lot of schematics, I've noticed that some placed the inicator led between the +/- power rails and some place it between the + rail and ground. Why? Is one way better than the other? I've built a solid state amp that has a tda7294 chip amp in the output and uses a split rail (+/-) supply. Any help would be apreciated.
phase396
 
Posts: 4
Joined: 24 Mar 2017, 05:07
Has thanked: 0 time
Have thanks: 0 time

Re: Led indicator in solid state amps

Postby thetragichero » 07 Mar 2019, 00:47

it shouldn't make much difference as long as you have a proper current limiting resistor in there (sometimes I can forget that a +/-15V supply is a 30V supply kinda thing)
thetragichero
 
Posts: 30
Joined: 31 May 2018, 19:26
Has thanked: 14 times
Have thanks: 8 times

Re: Led indicator in solid state amps

Postby deltafred » 08 Mar 2019, 10:18

The advantage to putting it across the +/- supplies is that it acts as a monitor so if it fails to light or is dim then you know something is wrong with the supply rails. If it is across the + only then the - rail can be faulty and it will still light normally.

The slight disadvantage is that more power is dissipated in the current limiting resistor.
Politics is the art of so plucking the goose as to obtain the most feathers with the least squawking. - R.G. 2011
Jeez, she's an ugly bastard, she makes my socks hurt. I hope it's no ones missus here. - Ice-9 2012
User avatar
deltafred
Opamp Operator
 
Posts: 1461
Joined: 06 Apr 2010, 17:16
Location: England
Has thanked: 389 times
Have thanks: 263 times


Return to Amplifiers

Who is online

Users browsing this forum: Google [Bot], lead2203 and 4 guests