Use a 2N3055 (or several in parallel) on heatsinks, the load is between
the Collector and Emitter. =20
 Bias the Base with a positive voltage between the Base and Emitter
(Emitter being the common point).
 Varying the voltage wil vary the conductance of the transistor, and
therefore very the load.  You can
 add an Ammeter in series with the load, and a voltmmeter across the
load to get power dissipated.
 I have used this method fmany times and it works well.  However, it
will only work for DC.
 You can use a power FET if you want to load an AC signal.

 Regards,

 Jim

> -------- Original Message --------
> Subject: [EE] Variable load testing
> From: V G <x.solarwind.x@gmail.com>
> Date: Wed, September 07, 2011 11:08 pm
> To: PICLIST <piclist@mit.edu>
>=20
>=20
> Hi all,
>=20
> I would like to make a simple device for load testing, with adjustable
> impedance (doesn't have to be continuously adjustable), so I can adjust t=
he
> amount of power it draws. The biggest concern I have is how to make a
> suitable dummy load that can handle up to 100W. I'm thinking just a set o=
f
> 16 ohm load coils in parallel, witch switches to enable/disable. That wou=
ld
> let me do for example, 16.0, 8.0, 5.33, 4.0, 3.2, 2.67, 2.29, 2.0, 1.78,
> 1.6, 1.45, 1.33, 1.23, 1.14, 1.07, 1.0 ohm impedance based on the number =
of
> coils I switch on. Where would I get such coils (around 1-2A, 16ohm)? Is
> there a more convenient impedance to use? Is there a better way to do the
> same thing? I would like to keep this cheap. Switches and coils is the
> cheapest method I can think of at the moment.
> --=20
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist


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