[SML] Dimming a 24vac load

Dan Sheehan dsheehan.sml at gmail.com
Fri Jul 3 00:55:34 UTC 2015


huh ?

I don't get it, but I should.

this is embarrassing...
I REALLY should get it...
I used to test active load components for ATE,
which are essentially diode bridges

can you post a sketch ?  with waveforms ?

is this a trick to control (dim) an AC load using a DC dimmer ?

I guess AC flowing from power to load through the bridge will attempt to
produce
rectified but unfiltered DC at rectifier + and - terminals,
but biasing this with DC from a DC-controlling dimmer will
alter the conductivity paths.. some of the AC will flow to the load,
some to the DC, depending on voltage...

is your use of the word "floating"  actually critically important,
meaning the AC source and the DC circuitry cannot have a common ground,
or magic smoke may be released  ?

am I guessing correctly ?  sort of ?

On Thu, Jul 2, 2015 at 8:19 PM, Jerry Durand via Stagecraft <
stagecraft at theatrical.net> wrote:

>  May not work for this application, but I'll let out a trick on AC loads.
>
> Assuming you don't mind a little voltage drop AND you have a floating
> dimmer or AC source...
>
> Split one wire going to the load, hook the power source to one ~ terminal
> of a bridge rectifier and the load to the other ~ terminal.
>
> Hook the - lead of the bridge to the dimmer ground and hook the + from the
> bridge to the dimmer output.  This assumes an NPN type of dimer, if you
> have a PNP type then you may have to swap wires around.
>
>
> On 07/02/2015 04:24 PM, Lyric Opera Kansas City via Stagecraft wrote:
>
> Hello Everyone,
>
>  I recently posted about dimming a 24v load which many probably assumed
> would be a 24v DC load as I did.  I found out that it is a 24vac load.
> They are tiny incandescent lights.  I will be pulling about 9.5A at 24vac.
> I thought I had secured a magnetic transformer that I could use to dim
> these lights, but it fell through.  Anyone know where I could get something
> that would work for this application?  I am not sure if there are any other
> products that I could get my hands on to do the trick.
>
>  Thanks,
>
>  Nate
>
>
> ____________________________________________________________
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>
>
> --
> Jerry Durand, Durand Interstellar, Inc.  www.interstellar.com
> tel: +1 408 356-3886, USA toll free: 1 866 356-3886
> Skype:  jerrydurand
>
>
> ____________________________________________________________
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> Stagecraft mailing list
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>



-- 
...Dan Sheehan
Fixer of things that break
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