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-   -   LED's,Current sinks and sofourth (http://www.diyaudio.com/forums/solid-state/7591-leds-current-sinks-sofourth.html)

CryingDragon 13th November 2002 06:39 PM

LED's,Current sinks and sofourth
 
I dono why people put current sinks in amp designs i mean all i do is put the - of the led to ground and put a 100K pot from the led (CW) to ground and decrease the resistance till the led looks nice but not over driven,anybody else do this?

halojoy 13th November 2002 11:54 PM

Re: LED's,Current sinks and sofourth
 
Quote:

Originally posted by CryingDragon
I dono why people put current sinks in amp designs i mean all i do is put the - of the led to ground and put a 100K pot from the led (CW) to ground and decrease the resistance till the led looks nice but not over driven,anybody else do this?
I do not understand how you mean.
The LED is there in an AMP to serve as a stabil votage referens.
This keep a transistor putting out a constant current.
This current is determined by the resistor from Emitter to ground.
The same current comes going into the Collector.

If you put the - of a LED to ground
and put a potentiometer from + to ground
nothing will happen

The LED is not used for its LIGHT in a current sink application.

mrfeedback 14th November 2002 12:52 AM

Power Indicator.
 
If using the Led as a power indicator, then putting a zener diode in series, and using a lower value resistor, power supply fluctuations become visible.

Eric.

CryingDragon 14th November 2002 03:34 AM

Arg guess i wasn't clear enough i mean ok i understand possibly using it for other reasons in an amp but i mean to run it for like as power light in stead of zener or whatever if you put the negitive of the led on the negitive rail and take the positive of the led and attach it to the center wiper and then take one leg and attach it to the positive rail you could light a led with stable light output and adjust the brightness of it too. mabey this thread made no sence.


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