From: pjs@gvgdsd.GVG.TEK.COM (Peter J. Stonard)
Newsgroups: sci.electronics
Subject: Re: Converting Fluorescent Lights
Date: 29 Dec 92 17:33:51 GMT
Organization: Grass Valley Group, Grass Valley, CA
NNTP-Posting-Host: gvgdsd.gvg.tek.com

In article <BzwH0B.K6L@uxa.ecn.bgu.edu> mgreeny@uxa.ecn.bgu.edu (Greeny) writes:
>
>I'm wondering how to go about converting two "old" fluorescent light

From time to time others do too. I did the modification to my fish
tanks some years ago, and sent the details to someone who asked just a
few weeks ago. Here they are:

Huett, you said:

> Peter,
> 
> I have a pretty high skill level, I'm a software engineer with 
> hardware training so
> I am very comfortable with electical and mechanical work. 
> I can even program and
> set the time/date on the VCR!! :) Feel free to "bore me with 
> techincal detail".
Very good!

> My light has the push and hold for a few seconds type switch, 
> I believe you called
> that one manual. Like you I wish to use a timer to control my 
> tank lighting.
> 
> Any info would be appreciated!!

The good news, you can keep the ballast that you have. The not so 
good news is that you must find a suitable trigger starter (canister)
and a socket for it. 

Most likely the home improvement stores will have a replacement 
canister starter, for about $1 each. You only need 
one but I'd get a spare so you're ready to replace it a couple of
years from now :*). Before going to the store make a note of the
bulb wattage and type number.  I don't think you had that info in
your post, an example would be "F40T12/CW" which is a 40 W 12/8 diameter
(ie 1 1/2 inch glass tube) Cool White. The starters are matched to
the bulb wattage, for example an FS-4 is for 40W bulbs, an FS-2 is
for 15 to 20W bulbs.

Once you have the starter canister you can go looking for a socket.
If you are lucky the home improvement store may have something you 
can adapt. If not then try a lighting specialty store. If all else
fails try an appliance repair store, sometimes these lamps are
used on stove tops. You may have to salvage one from a junk yard.
(I found some at an electronic parts surplus store and bought a half
dozen, the next week  they were all gone!).

As your lamp has a ballast in the power cord there are only two wires
entering the hood, I would guess. With the power off take the hood
apart and look for the switch. My guess here is that it has four
wires, two of one colour, two of another. One pair is closed when
the lamp is on the other pair are only closed while the switch is
pressed for starting. If you have a multimeter or DVM you can check
the switch on the ohms range of the meter. Make a note of any
connections before ripping it apart!

The cannister starter will be wired in place of these start contacts
on the switch.

Here is a crude diagram of what you likely have:

-------UUUUU--------------0   0----------|   |--------|
	BALLAST  	     /         xx|xxx|xxx     |
			   /           x \__/   x     |
	 	ON-OFF CONTACTS        x	x     |
				       x	x     |
				       x	x     0 ||
				       x	x	||
				       x	x     0 ||
				       x	x     |    START
				       x	x     |    CONTACTS
				TUBE   x	x     |
				       x  /--\  x     |
				       xx|xxx|xxx     |
-----------------------------------------|   |--------|

Electrically all you have to do is cut the 'START CONTACTS' wires at 
the switch and wire the canister starter in the same place. 

Mechanically you have to find a home for the canister starter and 
it's socket. The exact layout depends on your luck finding a socket 
and the space that you have in the hood. I've used screws on some 
and epoxy adhesive on the tough ones, just make sure you can get a
replacement canister in there when the time comes. Ordinary wire
nuts can be used to extend or connect the wiring.

Once modified the lamp will flicker a few times when it starts. If
the cannister is the wrong rating it may not light at all, or it
flickers constantly. Defective starters or a short across them will
cause the tube ends to glow (just like holding the 'start' switch
in your existing fixture). 

A bulb with poor contact due to aquarium water corrosion will not 
start. A quick test for this is to remove the canister starter 
and bridge the contacts in the starter socket to see if the tube 
ends light. 

At the end of it's life a tube may be prone to flicker (it's 
internal impedance increases to that of the starter strike voltage 
causing false starts). Some tubes fail when one or both internal
filaments open up. I think the Triton bulbs do this by design to
limit the number of hours that they burn before replacement.

That should cover it. Good luck, let me know if you get stuck and 
also when you have it running.

>In case you're wondering this is for my fish tanks... 

A shameless plug for the three *.aquaria groups: 
Alt.aquaria, Rec.aquaria and Sci.aquaria. 
You should find one or more at your site!


++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++
Peter J. Stonard        +                                /^\  /^\
Grass Valley Group      +                       /^\     /   \/
Grass Valley, CA. 95945 +                     /     \ /    /  
pjs@gvgspd.gvg.tek.com  +     Fish keeper in the Sierra Foothills
++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++=++
If it looks like; sounds like; quacks like; an Opinion. It's mine.
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