Ok the thing is that i need to drive a IR led . according to spec it need a
constant current of 250maA and 2.5 V across it. But when i used normal
supply i only manage to get 0.6V drop and current of 6mA
Is it possible to drive the led at 250mV??
----- Original Message -----
From: Wagner Lipnharski <wagner@USTR.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Sunday, November 28, 1999 2:17 AM
Subject: Re: constant voltage and current


> Dear Soon Lee,
>
> Unfortunately nobody can help you unless you say what you want.
>
> You can not have a constant voltage and constant current at the same
> time, because changing the load, at least current *or* voltage will
> change too, this is pure physics based on electricity rules.
>
> Yes, you can have a constant current generator, within limits of
> voltage, when then the output current will go down upon a high load,
>
> or,
>
> you can have a fixed voltage generator, with limits of current, when the
> output voltage will go down upon a low load.
>
> This is quite easy to build, nothing special, but it is impossible to
> help you unless you say exactly what you want.
>
> Reading your post, I can guess you want to build a battery recharger
> unit, but... you need to explain better.
>
> Wagner.