Inrush Current Limiting

[Brian Carling]

Time delay relay is the way to go.

I have a number of them available here if anyone wants to try using one!

On 4 Oct 99, at 11:18, Guy Dragoo wrote:

> You may want to try the inrush current limiter components (Inrush Current
> Limiters...basically a NTC thermister).  These simple devices go inline of
> the line voltage and provide a slower turn on.
> This brings up an interesting point for an inrush current limiting thread.
> I have been looking for a slow turn on device (other than current limiting
> thermisters which come on pretty quick and don't do any good if already
> heated up).
> This would be a good add in for the many tube rigs that are either converted
> to solid state rectifiers or just to add a gentle start up to some of those
> valuable old tubes and capacitors.
> Does anyone have any schematics, information, or insight  regarding such a
> beast?
> 73
> Guy AC5HL
>
> -----Original Message-----
> From: Richard Post [mailto:post at OUVAXA.CATS.OHIOU.EDU]
> Sent: Monday, October 04, 1999 11:47 AM
> To: BOATANCHORS at LISTSERV.TEMPE.GOV
> Subject: OT: Dual voltage mod for projector lamp
>
>
>
> Robert,
>
>
> One option that will increase the life of a 120 volt bulb is to wire a diode
> in series with it. That drops the RMS heating equivalent to 85 volts. (120
> divided by square root of 2) A simple switch can be used to short the diode
> for full voltage to the lamp. A time-delay relay or triac can do the timing
> for you but the 85 volts equivalent may be enough for some viewing. As I
> recall, but it's been a long time ago, the Pageant uses a 120 volt lamp. If
> not, forget this solution. A projection lamp rated at 85 volts already uses
> this method.
>
>
> Practically all modern overhead projectors use this diode solution
> permanently so that longer-lasting heavier filament lamps (rated at 85
> volts) can be connected cheaply.
>
>
> BA radio tie-in: This is a partial solution to replacing the series-dropping
> resistance-line-cord of the 1930s and 40s. The diode generates little or no
> heat and, together with a smaller resistor in series with the filament
> string, can be used to replace the rather dangerous and unobtanium
> resistance line cord or a ballast tube.
>
>
> Rich
>
> Boatanchor Pix website - KB8TAD
>
> http://oak.cats.ohiou.edu/~postr/bapix/
>
>
>
> >Date: Sat, 02 Oct 1999 16:51:33 -0500
>
> >From: "Robert M. Bratcher Jr." <bratcher at PDQ.NET>
>
> >Subject: OT: Dual voltage mod for projector lamp
>
> >Sender: Boat Anchor Owners and Collectors List
> <BOATANCHORS at LISTSERV.TEMPE.GOV>
>
> >X-Sender: bratcher at pop.pdq.net
>
> >To: BOATANCHORS at LISTSERV.TEMPE.GOV
>
> >Reply-to: "Robert M. Bratcher Jr." <bratcher at PDQ.NET>
>
> >MIME-version: 1.0
>
> >X-AirNote: 1
>
> >Comments: To: 16mmfilm at onelist.com
>
> >Comments: cc: fcls at flash.net, glowbugs at piobaire.mines.uidaho.edu,
>
> > boatanchors at qth.net
>
> >
>
> >Does anybody know where I could find a solid state schematic for a dual
>
> >voltage supply that would give about 30v for perhaps 5 seconds then the
>
> >full 120v? Or how to make one? I'd like to extend the life of my projector
>
> >bulbs. Sure they go out after about 25 hours but I would love to double or
>
> >triple that life. For those of you not on the 2 film collector lists bulbs
>
> >cost around $23 apiece.
>
> >
>
> >If your not on the film lists then please respond directly to me. The
>
> >16mmfilm &fcls users can just reply to the list if they wish.
>
> >Thanks very much. I'd like to install something like this in my Kodak
> Pageant.
>
> >
>
> >bratcher at pdq.net
>
> >Robert M. Bratcher Jr.
>
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Numerous radios, accessories and parts for sale at:
http://www.geocities.com/CapeCanaveral/Hall/8701/trade.htm

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