I'm about to put together a chipamp (Brian GT) LM3886 kit and was wondering if I could connect the LED in my mains power on/off switch to the LED connection point on the PSU board in place of the one which came with the kit.
I don't see why not but thought i'd ask before I went ahead.
Cheers
Davy
I don't see why not but thought i'd ask before I went ahead.
Cheers
Davy
Im sure you can but first take into consideration what voltage the LED in the power switch needs .....
Most LED's need a resistor in series with the LED , the value of the resistor is determined by the source voltage and current draw and voltage of the LED ..
On your PSU board there is a resistor in series with where the LED goes , this resistor drops the PSU voltage down to about 1.5V as most standard LED's run at 1.5V , the LED in your power switch probably expects 12v DC and has a resistor in series with its LED built in .....
So what you might have to do is adjust the value of the LED resistor on the PSU board or else your LED in the power switch might not light up .....
Cheers
Most LED's need a resistor in series with the LED , the value of the resistor is determined by the source voltage and current draw and voltage of the LED ..
On your PSU board there is a resistor in series with where the LED goes , this resistor drops the PSU voltage down to about 1.5V as most standard LED's run at 1.5V , the LED in your power switch probably expects 12v DC and has a resistor in series with its LED built in .....
So what you might have to do is adjust the value of the LED resistor on the PSU board or else your LED in the power switch might not light up .....
Cheers
Cheers i'll check that out.
Originally I was going to tap the roughly 30v DC from one rail using a couple of 2W resistors the seller sent me but I came across a picture of a chipamp in which the builder had substituted the led on the board for the one in his switch, cant remember who built that amp but I think i have a copy of the picture.
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I assume the purpose is to indicate that the PSU is working (well enough to light the LED)? Otherwise the LED connection point on the PSU board could likely be left empty, or stuffed with the LED flush to the board and hidden inside the enclosure. The mains switch LED continues as the power-on indicator.
Cheers Jon, thought the ones he sent were a bit on the large side for 30v.
Above is the build which gave me the idea about substituting the board led for the power switch indicator one. It would be neat if i could do the same thing.
btw my build will be very similar to this using a shielded transformer and the same case except i got them to cut the power socket hole in the middle of the rear panel and i wont be fitting the volume pot.
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Hi Jon, can I just confirm that 2k7 would be ok? the led indicator terminal input is 6v.
The supplier sent 2 x 4.6k 2 watt resistors with their legs twisted together giving me a reading of 2.2k, I know they are a bit large in wattage but would they be close enough for 6v?
Cheers
Davy
You can use the resistors you got for the LED. It will shine slighly brighter than with 2.7k.
As long as the LED can handle 20mA you can go down to 1.2K. The bigger the resistor is the less light the LED will give. I don't like if a LED shines my face off when I only want to see if it is turned on or not.
You can also use one 4.6K res also for testing.
As long as the LED can handle 20mA you can go down to 1.2K. The bigger the resistor is the less light the LED will give. I don't like if a LED shines my face off when I only want to see if it is turned on or not.
You can also use one 4.6K res also for testing.
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