[Jukebox-list] External start switch and Megger

[Ron Rich]

The timing was my question also. I think that you may have hit it "spot-on", but I still worry about overheating the start windings, using that "timer". Ron Rich


--- On Thu, 5/8/08, Di Di Mao <ddmaow at yahoo.com> wrote:

> From: Di Di Mao <ddmaow at yahoo.com>
> Subject: [Jukebox-list] External start switch and Megger
> To: "Juke List" <jukebox-list at lists.netlojix.com>
> Date: Thursday, May 8, 2008, 9:31 PM
> Reminds me of the days when the early series Simpson
> 260 meters reigned supreme.  They used a 22.5 volt
> battery in the ohmmeter.  Using one to test the then
> available Germanium transistors was disasterous!
> 
> When I tried to imagine how you would make an external
> switch it occurred to me you need the motor speed as
> an input factor.  Without it, you're just
> approximating the actual function of the centrifugal
> switch.  In other words, I dismissed the idea as
> potentially unreliable, at least in some situations.
> 
> When the link to the device was posted, I could see
> that they are overlooking all that!
> 
> So what's inside? Just a timing circuit and a triac,
> most likely.  A one shot of some sort, maybe a 555
> timer (or a relay).  You would set the time to be long
> enough for the motor to start under worst case
> conditions.  A little extra on time for the start
> windings probably wouldn't be very bad, but too much
> will overheat the motor in short order.  Of course,
> you need to have access to the start winding.
> 
> 
> 
>      
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