Re: [CAD_CAM_EDM_DRO] Proportional Controller ?

datac@... wrote:

> Maybe someone can Identify what I have.
>
> I picked up (2) devices that look exactly like a solid state relay.
> But the are not, they say "proportional controller" on them.
>
> Made by Douglas Randall, model # R25A
> On one side, terminals 1 and 2 say AC Load - 25 amp
> The other side, terminals 3 and 4 say Resistance.
>
> I did a search that turned up little. I have some assumptions to what
> they do but maybe someone who actually knows could explain it and give
> an illustration on a typical application.
>
> I'd rather that than connect it up and do a little experimenting.

What this does is control the power output by regulating the phase
angle of triggering Triacs or SCRs. Assuming there are no other
terminals, you hook a light bulb in series with the AC load terminals
and the power line. Now, if you hook a variable resistor between the
2 'Resistance' terminals, the light bulb should vary from off to full on.
A pretty neat device, and probably pretty expensive, maybe over $200.

Jon