Pifco sun lamp. - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Geoff 555 · 6th Jan 2011, 1:24 pm

Hi thank you copper coated rods look like the way to go. John thank you for taking the trouble to look, AJS thank you also. not wishing to go OT but -------- Where to get Ferric Chloride please ?
Cheers.
Geoff.

ppppenguin · 6th Jan 2011, 1:35 pm

RS sell Ferric chloride in various packages. For example: http://uk.rs-online.com/web/search/s...duct&R=4349056

Guess that Rapid and Farnell sell it too.

As an alternative dilute nitric acid will take the copper off without touching the carbon.

Geoff 555 · 6th Jan 2011, 6:31 pm

Thank you Jeffrey, I am getting more stupid as the days go by, recognised the name but couldnt think what it was for. ETCHING pcb's etc. Apologies for asking such a +++++++ question.
Cheers.
Geoff.

kalee20 · 6th Jan 2011, 6:42 pm

Quote:

Originally Posted by AlanBeckett

I don't expect the copper is very thick. A good rub with emery cloth would probably do it.
Alan

Certainly cinema carbons were plated up to a fair thickness - 3 thou' or so. (For comparison, a typical PCB track thickness is 1 thou'). It could be removed by emery paper, but only with a lot of rubbing!

But I'm puzzled as to why remove copper plating anyway? It improves conductivity up to near the region of the arc, and also stops the carbon from vapourising along its length (subliming is technically the correct term). Near the arc, the copper just melts off for the last half inch or so.

AlanBeckett · 6th Jan 2011, 7:26 pm

Quote:

Originally Posted by kalee20

Certainly cinema carbons were plated up to a fair thickness

I don't remember that being the case, but it was a long time go.

Quote:

Originally Posted by kalee20

.... 3 thou' or so. (For comparison, a typical PCB track thickness is 1 thou'). It could be removed by emery paper, but only with a lot of rubbing!

1 oz Copper is 1.4 thou if I remember correctly - 35 micrometres - which I never had any great difficuty either scraping or sanding off. Anyway, if you're really keen you could always spin it up in your drill or lathe

Alan

Graeme Murphy · 7th Jan 2011, 12:35 am

I wonder if my mother still has this tucked away in the loft......

Tractorfan · 7th Jan 2011, 3:31 pm

Hi,
I was experimenting a while back with carbon rods out of dead torch batteries and a low voltage/high current transformer. It sort of worked but didn't cause radio interference

feeding the carbons was the tricky bit

. I watched the reflected light on a wall so I wasn't staring at the arc. Still risky, but I got away with it.
Cheers, Pete

Lucien Nunes · 8th Jan 2011, 3:23 am

The carbons normally used in sunlamps were often used in complementary pairs with different core materials, e.g. to encourage pip and crater formation even on AC which would otherwise erode the two carbons equally. Despite their similarities to basic low-intensity projection arc carbons, some were loaded with materials other than pure carbon. Pifco used to include in the boxes of carbons a list of compatible pairings - see attached pic. As far as I know they tended to use Morganite products, whereas the Wonder Health Ray mentioned above was supplied with Ship carbons.

Copper-coated types were for HI (high intensity) arcs - I wouldn't recommend burning them in a sunlamp, as the copper sputtering and debris from the mineral salt cores could make a mess of the lamp and give off some nasty niffs that would normally be extracted via the lamphouse flue. If you experiment with removing the copper chemically, remember the black bit is not pure carbon but contains all sorts of additives. Carbons that have been damp sometimes do not burn well!

Lucien

Geoff 555 · 9th Jan 2011, 12:29 am

Thank you Lucien I was concerned about the copper coating. I thought it may do nasty things. I will keep looking.
Cheers.
Geoff.

Lucien Nunes · 9th Jan 2011, 12:48 am

I was just going to suggest that I could send you a couple of genuine sunlamp carbons, but have discovered the box is not where I thought it should be. That's usually down to my memory and I just look on the database, but the database doesn't know either. I will keep looking.

In the meantime this company claim to have LI carbons.

Lucien

6th Jan 2011, 1:24 pm	#21
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Pifco sun lamp. Hi thank you copper coated rods look like the way to go. John thank you for taking the trouble to look, AJS thank you also. not wishing to go OT but -------- Where to get Ferric Chloride please ? Cheers. Geoff.

6th Jan 2011, 1:35 pm	#22
ppppenguin Retired Dormant Member Join Date: Dec 2003 Location: North London, UK. Posts: 6,168	Re: Pifco sun lamp. RS sell Ferric chloride in various packages. For example: http://uk.rs-online.com/web/search/s...duct&R=4349056 Guess that Rapid and Farnell sell it too. As an alternative dilute nitric acid will take the copper off without touching the carbon.

6th Jan 2011, 6:31 pm	#23
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Pifco sun lamp. Thank you Jeffrey, I am getting more stupid as the days go by, recognised the name but couldnt think what it was for. ETCHING pcb's etc. Apologies for asking such a +++++++ question. Cheers. Geoff.

7th Jan 2011, 12:35 am	#26
Graeme Murphy Tetrode Join Date: Oct 2009 Location: Blyth, Northumberland, UK. Posts: 62	Re: Pifco sun lamp. I wonder if my mother still has this tucked away in the loft......

7th Jan 2011, 3:31 pm	#27
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,182	Re: Pifco sun lamp. Hi, I was experimenting a while back with carbon rods out of dead torch batteries and a low voltage/high current transformer. It sort of worked but didn't cause radio interference feeding the carbons was the tricky bit . I watched the reflected light on a wall so I wasn't staring at the arc. Still risky, but I got away with it. Cheers, Pete __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

8th Jan 2011, 3:23 am	#28
Lucien Nunes Rest in Peace Join Date: Apr 2008 Location: London, UK. Posts: 2,508	Re: Pifco sun lamp. The carbons normally used in sunlamps were often used in complementary pairs with different core materials, e.g. to encourage pip and crater formation even on AC which would otherwise erode the two carbons equally. Despite their similarities to basic low-intensity projection arc carbons, some were loaded with materials other than pure carbon. Pifco used to include in the boxes of carbons a list of compatible pairings - see attached pic. As far as I know they tended to use Morganite products, whereas the Wonder Health Ray mentioned above was supplied with Ship carbons. Copper-coated types were for HI (high intensity) arcs - I wouldn't recommend burning them in a sunlamp, as the copper sputtering and debris from the mineral salt cores could make a mess of the lamp and give off some nasty niffs that would normally be extracted via the lamphouse flue. If you experiment with removing the copper chemically, remember the black bit is not pure carbon but contains all sorts of additives. Carbons that have been damp sometimes do not burn well! Lucien Attached Thumbnails

9th Jan 2011, 12:29 am	#29
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Pifco sun lamp. Thank you Lucien I was concerned about the copper coating. I thought it may do nasty things. I will keep looking. Cheers. Geoff.

9th Jan 2011, 12:48 am	#30
Lucien Nunes Rest in Peace Join Date: Apr 2008 Location: London, UK. Posts: 2,508	Re: Pifco sun lamp. I was just going to suggest that I could send you a couple of genuine sunlamp carbons, but have discovered the box is not where I thought it should be. That's usually down to my memory and I just look on the database, but the database doesn't know either. I will keep looking. In the meantime this company claim to have LI carbons. Lucien