Vintage capacitors? - UK Vintage Radio Repair and Restoration Discussion Forum

Retired · 2nd Nov 2009, 5:15 pm

Hi,
A few years ago I was repairing an expensive radio for a friend that required new capacitors. Modern capacitors would look ghastly in this situation and as vintage types were not available decided to make my own.

I bought a roll of brown wrapping paper and cut this into A4 size sheets. Using crafters PVA adhesive each sheet was wrapped around a highly polished waxed steel rod and this formed long paper tubes when slid off; the tubes being quite strong once the glue dried. Different diameters of paper tube were made to suit different modern capacitors.

An original capacitor was measured for length and the tubes were cut on my band saw removing rough edges with abrasive paper.

I scanned one of the labels taken from an original and tidied up the image. Multiple images were pasted onto an A4 sized sheet using the computer and with A4 size brown paper in the printer the new blocks of labels were printed then cut out individually using scissors. Each paper tube received a label attached with more PVA adhesive.

Modeling clay was purchased from Hobbycraft and the clay was rolled out pastry fashion using a length of old conduit with 1/8” thick spacers to give a uniform thickness to the clay. A hollow tapered punch was turned in the lathe and this was used like a pastry cutter and using a close fitting rod turned with a protruding center point the newly cut clay plugs were ejected. These clay plugs once baked in the oven were a nice tight fit in the ends of the tubes the tapers making insertion easier.

Paraffin wax was also bought from Hobbycraft (no longer stocked) and this was used to encapsulate the new modern capacitor within the tube; wooden racks were made that allowed the new capacitors to be mounted vertically to aid filling with molten wax. These could be done in bulk.

Each plug was drilled to accept the wire extension which had been soldered into place on the modern capacitor after first having the wire end coil formed using my miniature wire winder as shown in another thread. A plug was pushed firmly into place in one end of the tube and the modern capacitor slid in; paraffin wax was heated in a double container and using a syringe surplus from ink cartridge filling the tube was almost filled with hot wax and the second plug was pushed home. A whole batch was quickly done this way.

The wires were then bent upwards forming a “U” shape enabling both ends to be gripped and the new capacitor was dipped into the molten wax; removed and immediately dipped straight into a bowl of cold water. After the initial dip in wax all were given a second and final dip. The wax was coloured with dark brown shoe polish.

I really went to town with making these capacitors as I also experimented at making small machines for paper tube forming and applying adhesive. Col.

Panrock · 2nd Nov 2009, 5:50 pm

Nice job. These look very like (identical?) to some I bought at an NVCF a year or two ago. I've still some left - they've come in very useful.

Steve

Retired · 2nd Nov 2009, 6:50 pm

Hi Steve,
Thanks for this; yes they are most likely from my production line. I made a large batch and a friend kindly took some along to meetings and sold them. I tried various ways of producing them from just filling with wax to cutting end plugs out of hardboard; the hardboard was extremely hostile to tool bits though.

I enjoyed making them and covered my monetry outlay so gained a lot of experience free of charge apart from a lot of labour. I'm pleased to hear they have been useful. Col.

YT2095UK · 2nd Nov 2009, 6:57 pm

boy o boy do I wish I had some of those right now!

deserves a 5 Star Thread rating

brendan99 · 3rd Nov 2009, 1:41 am

That's deadly Retired. Fantastic effort and the result is definitely authentic looking. If you're going to sell them be careful, make sure you derate the temperature profile by at least 50%, they're in paper and wak sleeping bags now, not what the designers meant them to be in ..

Mike Phelan · 3rd Nov 2009, 9:49 am

Great minds think alike, Col. I tried rolling a tube up from ‘Gumstrip’ adhesive brown paper tape – it looked OK, but went wrinkly when dry – no good. Plan B; examine a toilet-roll former to see how it is made. I know, but you have to do something when you forget to take a book with you!

They appear to be made from two strips spirally wrapped in opposite directions, so this idea was tried with strips cut from a manilla folder, and stuck with wallpaper paste. Result was better, but I had great difficulty removing it from the alloy rod used as a former, despite the fact I had wrapped it in cling film.

Final attempt – cut one side from a brown foolscap envelope, wrap it round alloy rod, and stick the last inch or so with PVA glue. Perfect, and slid off rod OK. I used pinking shears to cut the glued edge, borrowed from the distaff side.

Stuck the labels on with Pritt Stick, and dunked the lot in water-based clear lacquer, which gives it a slight yellowish appearance.

GMB · 3rd Nov 2009, 10:29 am

This looks so brilliantly well done that I can't help but wonder if in decades to come there will be a thread discussing the observation that some "old" capacitors seem not to have suffered any degradation at all.

Do you add a discrete date to avoid confusion?

Retired · 3rd Nov 2009, 12:00 pm

Hi,
Many thanks for the kind comments.
YT209 I've sent a PM and hopefully I might still have the ones you require although my stock is virtually depleted. Cross your fingers and hope.

A very good point Brendan but I only made them as an experiment just to see if I could make them with no intention of selling as radio is purely a hobby to me.

Top job Mike; I find the hardest part is getting the A4 sheet of paper to start neatly whilst wrapping it around the rod whilst tube forming. I tried WD40 to lubricate the rod but ended up waxing it; the tubes were still tight to remove but with practice it got easier.

No; I didn't add a date GMB but just kept the label original; it would be interesting to see the expression on a restorers face if one of these is pulled apart in many years time though. Col.

Boom · 3rd Nov 2009, 1:28 pm

Lovely work Col.

I either pop a piece of paper in the back of the set with notes on what has been done with any hidden parts or sellotape it under the cabinet. I'm getting to the point where I have so many sets that I could easily try to recap a set that has already been done with stuffed caps'.

Retired · 3rd Nov 2009, 3:51 pm

Thanks David,
Yes it's a good idea to keep some kind of record. I used to keep notes of all work done on floppy disc but for the last few years start a new CD for every set I work on recording every detail otherwise as you correctly point out it's so easy to lose the plot. Col.

2nd Nov 2009, 5:15 pm	#1
Retired Heptode Join Date: Mar 2009 Location: Fenay Bridge, Huddersfield. UK. Posts: 673	Vintage capacitors? Hi, A few years ago I was repairing an expensive radio for a friend that required new capacitors. Modern capacitors would look ghastly in this situation and as vintage types were not available decided to make my own. I bought a roll of brown wrapping paper and cut this into A4 size sheets. Using crafters PVA adhesive each sheet was wrapped around a highly polished waxed steel rod and this formed long paper tubes when slid off; the tubes being quite strong once the glue dried. Different diameters of paper tube were made to suit different modern capacitors. An original capacitor was measured for length and the tubes were cut on my band saw removing rough edges with abrasive paper. I scanned one of the labels taken from an original and tidied up the image. Multiple images were pasted onto an A4 sized sheet using the computer and with A4 size brown paper in the printer the new blocks of labels were printed then cut out individually using scissors. Each paper tube received a label attached with more PVA adhesive. Modeling clay was purchased from Hobbycraft and the clay was rolled out pastry fashion using a length of old conduit with 1/8” thick spacers to give a uniform thickness to the clay. A hollow tapered punch was turned in the lathe and this was used like a pastry cutter and using a close fitting rod turned with a protruding center point the newly cut clay plugs were ejected. These clay plugs once baked in the oven were a nice tight fit in the ends of the tubes the tapers making insertion easier. Paraffin wax was also bought from Hobbycraft (no longer stocked) and this was used to encapsulate the new modern capacitor within the tube; wooden racks were made that allowed the new capacitors to be mounted vertically to aid filling with molten wax. These could be done in bulk. Each plug was drilled to accept the wire extension which had been soldered into place on the modern capacitor after first having the wire end coil formed using my miniature wire winder as shown in another thread. A plug was pushed firmly into place in one end of the tube and the modern capacitor slid in; paraffin wax was heated in a double container and using a syringe surplus from ink cartridge filling the tube was almost filled with hot wax and the second plug was pushed home. A whole batch was quickly done this way. The wires were then bent upwards forming a “U” shape enabling both ends to be gripped and the new capacitor was dipped into the molten wax; removed and immediately dipped straight into a bowl of cold water. After the initial dip in wax all were given a second and final dip. The wax was coloured with dark brown shoe polish. I really went to town with making these capacitors as I also experimented at making small machines for paper tube forming and applying adhesive. Col. Attached Thumbnails

2nd Nov 2009, 5:50 pm	#2
Panrock Nonode Join Date: Feb 2005 Location: Worcestershire, UK. Posts: 2,535	Re: Vintage capacitors? Nice job. These look very like (identical?) to some I bought at an NVCF a year or two ago. I've still some left - they've come in very useful. Steve __________________ https://www.radiocraft.co.uk

2nd Nov 2009, 6:50 pm	#3
Retired Heptode Join Date: Mar 2009 Location: Fenay Bridge, Huddersfield. UK. Posts: 673	Re: Vintage capacitors? Hi Steve, Thanks for this; yes they are most likely from my production line. I made a large batch and a friend kindly took some along to meetings and sold them. I tried various ways of producing them from just filling with wax to cutting end plugs out of hardboard; the hardboard was extremely hostile to tool bits though. I enjoyed making them and covered my monetry outlay so gained a lot of experience free of charge apart from a lot of labour. I'm pleased to hear they have been useful. Col.

2nd Nov 2009, 6:57 pm	#4
YT2095UK Retired Dormant Member Join Date: Sep 2009 Posts: 487	Re: Vintage capacitors? boy o boy do I wish I had some of those right now! deserves a 5 Star Thread rating

3rd Nov 2009, 1:41 am	#5
brendan99 Retired Dormant Member Join Date: Mar 2006 Location: Portmarnock, Dublin. Posts: 11	Re: Vintage capacitors? That's deadly Retired. Fantastic effort and the result is definitely authentic looking. If you're going to sell them be careful, make sure you derate the temperature profile by at least 50%, they're in paper and wak sleeping bags now, not what the designers meant them to be in ..

3rd Nov 2009, 9:49 am	#6
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Re: Vintage capacitors? Great minds think alike, Col. I tried rolling a tube up from ‘Gumstrip’ adhesive brown paper tape – it looked OK, but went wrinkly when dry – no good. Plan B; examine a toilet-roll former to see how it is made. I know, but you have to do something when you forget to take a book with you! They appear to be made from two strips spirally wrapped in opposite directions, so this idea was tried with strips cut from a manilla folder, and stuck with wallpaper paste. Result was better, but I had great difficulty removing it from the alloy rod used as a former, despite the fact I had wrapped it in cling film. Final attempt – cut one side from a brown foolscap envelope, wrap it round alloy rod, and stick the last inch or so with PVA glue. Perfect, and slid off rod OK. I used pinking shears to cut the glued edge, borrowed from the distaff side. Stuck the labels on with Pritt Stick, and dunked the lot in water-based clear lacquer, which gives it a slight yellowish appearance. Attached Thumbnails __________________ Mike.

3rd Nov 2009, 10:29 am	#7
GMB Dekatron Join Date: Aug 2003 Location: near Reading (and sometimes Torquay) Posts: 3,101	Re: Vintage capacitors? This looks so brilliantly well done that I can't help but wonder if in decades to come there will be a thread discussing the observation that some "old" capacitors seem not to have suffered any degradation at all. Do you add a discrete date to avoid confusion?

3rd Nov 2009, 12:00 pm	#8
Retired Heptode Join Date: Mar 2009 Location: Fenay Bridge, Huddersfield. UK. Posts: 673	Re: Vintage capacitors? Hi, Many thanks for the kind comments. YT209 I've sent a PM and hopefully I might still have the ones you require although my stock is virtually depleted. Cross your fingers and hope. A very good point Brendan but I only made them as an experiment just to see if I could make them with no intention of selling as radio is purely a hobby to me. Top job Mike; I find the hardest part is getting the A4 sheet of paper to start neatly whilst wrapping it around the rod whilst tube forming. I tried WD40 to lubricate the rod but ended up waxing it; the tubes were still tight to remove but with practice it got easier. No; I didn't add a date GMB but just kept the label original; it would be interesting to see the expression on a restorers face if one of these is pulled apart in many years time though. Col.

3rd Nov 2009, 1:28 pm	#9
Boom Retired Dormant Member Join Date: Jan 2007 Location: Westbury, Wiltshire, UK. Posts: 2,451	Re: Vintage capacitors? Lovely work Col. I either pop a piece of paper in the back of the set with notes on what has been done with any hidden parts or sellotape it under the cabinet. I'm getting to the point where I have so many sets that I could easily try to recap a set that has already been done with stuffed caps'.

3rd Nov 2009, 3:51 pm	#10
Retired Heptode Join Date: Mar 2009 Location: Fenay Bridge, Huddersfield. UK. Posts: 673	Re: Vintage capacitors? Thanks David, Yes it's a good idea to keep some kind of record. I used to keep notes of all work done on floppy disc but for the last few years start a new CD for every set I work on recording every detail otherwise as you correctly point out it's so easy to lose the plot. Col.