At 09:36 PM 11/27/99 +0800, you wrote:
>Hi guys
>
>Got a big program hope you can help.
>
>Does anyone know of any circuit that is able to produce a constant
>current(250mA) and voltage(about 5 to 10V).If you have it can you sent it to
>me ASAP. thanks
>
>if you have any infor please mail to me

Take a look at just about any data sheet for a 3-pin regulator--should be a
circuit there for constant current.  All you need is the regulator and one
resistor to set the current.  LM317's work fairly well and can handle the
current.  You will lose about 1.25 volts across the resistor.  AND be sure
to put a 1 uF cap across the resistor as well--really does wonders for
current stability.  DO NOT put a cap from the output to ground, however.

Kelly

William K. Borsum, P.E. -- OEM Dataloggers and Instrumentation Systems
<borsum@dascor.com> & <www.dascor.com>San Diego, California, USA