Re: simple 150uA constant current supply

Dave wrote:
Thanks Martin but, it's not homework, I don't have any space for an IC and this is battery powered.
I can only spare about 30uA to 'generate' this supply.
Thanks
Dave


Uhm, so you contemplated a regulator chip but don't want an IC. Then you said you have 30uA to generate 150uA but do not want PWM. That's all quite confusing. Maybe you should share some more data.


"Martin Griffith" <mart_in_medina@xxxxxxxx> wrote in message news:o3svu3dhvijcaoq14kjm1v2ll6o9qapo8m@xxxxxxxxxx
On Sun, 30 Mar 2008 20:49:36 +0100, in sci.electronics.design "Dave"
<daveh@xxxxxxxxxxxx> wrote:

I would like to find the simplest way to provide a constant current of
around 150uA (+/-20%) at around 2V.
This needs to be discrete components rather than IC and should not involve
pulse width modulation.
The simplest form I thought of was a 3v voltage reg with a 20K resistor
between it's 'reference ground' and the output but this seems clumsy.
Anyone ?
Thanks
Dave

Sounds like a homework assignment, but I'd start off with a 150V rail
and a 1Meg resistor


martin




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