Lamp limiter usefulness ? - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

Refugee · 18th Jan 2018, 12:57 am

I built mine back in the late 1970s.
Two things that none so far have included are the terminals for measuring current consumption these being shorted out with the bypass switch.
For low current and accurate readings the bulb has to be removed.
Secondly with the lamp in circuit the earth is routed via a neon bulb as a crude insulation test.
I never had a single pole switch at the time so I made the most of a double pole one.

Tractionist · 18th Jan 2018, 7:45 am

Very cunning - and sexy! Makes through/on-going-restoration quiescent monitoring very straight-forward ............

Refugee · 18th Jan 2018, 2:00 pm

With the double pole switch being what I had to hand the extra contacts were "use it or loose it" so I made the most of them.

Tractionist · 18th Jan 2018, 5:18 pm

You did good ...... surprised you're still a refugee !!!!!

factory · 18th Jan 2018, 10:15 pm

Here is mine, which was made up from some of the vintage electrical fittings I have.
I'm tempted to build a bigger version now I have some higher wattage lamps, which would be more useful for some of my vintage HP test equipment.

David

Refugee · 19th Jan 2018, 1:08 am

Quote:

Originally Posted by Tractionist

You did good ...... surprised you're still a refugee !!!!!

The story about my screen name would be mega off topic.
The moderators would delete the entire thread

What you have to remember is that when I built my lamp limiter the only meters we had were analogue and would suffer from inrush so the switching had more value in the day.

robin0577 · 19th Jan 2018, 1:10 am

OK then, since everyone seems to be doing it, here's mine. A very simple boring one I'm afraid, made a couple of years ago with current MK parts...

HamishBoxer · 19th Jan 2018, 9:58 am

If you cannot get the standard bulbs go for "Rough Service" ones they are cheap enough on Ebay.

Tractionist · 19th Jan 2018, 10:40 am

Quote:

Originally Posted by factory

Here is mine, which was made up from some of the vintage electrical fittings I have.
I'm tempted to build a bigger version now I have some higher wattage lamps, which would be more useful for some of my vintage HP test equipment.

'Vintage' ! Keep the faith eh?

Quote:

Originally Posted by robin0577

OK then, since everyone seems to be doing it, here's mine. A very simple boring one I'm afraid, made a couple of years ago with current MK parts...

'Bullet-proof' ?

boxdoctor · 24th Jan 2018, 12:33 pm

Lamp limiters are a real boon when repairing solid-state audio equipment,too.
I must have saved the "re-replacement" of many expensive STKxxx audio chips by using a lamp limiter at first switch-on after replacing the part. Failure is often caused by small electrolytics going high E.S.R. but measuring ok with a tester. Everything looks to be ok, but the amp will burst into oscillation at swith-on, due to these caps being faulty. This destroys the new chip, and, if you are unlucky, the loudspeaker(s) as well!.
The lamp limiter, by limiting the available current, saves both the chip and, of course, the speakers.
I use a 60 watt lamp initially, and if all seems Ok, a 100watt. But if there is still a problem, it usually reveals itself with the 60 watt.
Running equipment up on a Variac is all very well, but it is still "hard" mains, and if anything is wrong, the "unlimited" power available will usually destroy the replaced parts. The variac very rarely gets used when I do this type of repair. Tony

18th Jan 2018, 12:57 am	#41
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,554	Re: Lamp limiter usefulness ? I built mine back in the late 1970s. Two things that none so far have included are the terminals for measuring current consumption these being shorted out with the bypass switch. For low current and accurate readings the bulb has to be removed. Secondly with the lamp in circuit the earth is routed via a neon bulb as a crude insulation test. I never had a single pole switch at the time so I made the most of a double pole one. Attached Thumbnails

18th Jan 2018, 7:45 am	#42
Tractionist Heptode Join Date: Apr 2016 Location: Cheltenham, Gloucestershire, UK. Posts: 875	Re: Lamp limiter usefulness ? Very cunning - and sexy! Makes through/on-going-restoration quiescent monitoring very straight-forward ............ __________________ Red to red, black to black. Throw the switch and stand well back!

18th Jan 2018, 2:00 pm	#43
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,554	Re: Lamp limiter usefulness ? With the double pole switch being what I had to hand the extra contacts were "use it or loose it" so I made the most of them.

18th Jan 2018, 5:18 pm	#44
Tractionist Heptode Join Date: Apr 2016 Location: Cheltenham, Gloucestershire, UK. Posts: 875	Re: Lamp limiter usefulness ? You did good ...... surprised you're still a refugee !!!!! __________________ Red to red, black to black. Throw the switch and stand well back!

18th Jan 2018, 10:15 pm	#45
factory Octode Join Date: Jul 2009 Location: Cheshire, UK. Posts: 1,740	Re: Lamp limiter usefulness ? Here is mine, which was made up from some of the vintage electrical fittings I have. I'm tempted to build a bigger version now I have some higher wattage lamps, which would be more useful for some of my vintage HP test equipment. David Attached Thumbnails

19th Jan 2018, 1:10 am	#47
robin0577 Pentode Join Date: Oct 2010 Location: London, UK. Posts: 139	Re: Lamp limiter usefulness ? OK then, since everyone seems to be doing it, here's mine. A very simple boring one I'm afraid, made a couple of years ago with current MK parts... Attached Thumbnails __________________ "Broken we can fix, cr*p is a design issue"

19th Jan 2018, 9:58 am	#48
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: Lamp limiter usefulness ? If you cannot get the standard bulbs go for "Rough Service" ones they are cheap enough on Ebay. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

24th Jan 2018, 12:33 pm	#50
boxdoctor Rest in Peace Join Date: Sep 2010 Location: Ripley, Derbyshire, UK. Posts: 785	Re: Lamp limiter usefulness ? Lamp limiters are a real boon when repairing solid-state audio equipment,too. I must have saved the "re-replacement" of many expensive STKxxx audio chips by using a lamp limiter at first switch-on after replacing the part. Failure is often caused by small electrolytics going high E.S.R. but measuring ok with a tester. Everything looks to be ok, but the amp will burst into oscillation at swith-on, due to these caps being faulty. This destroys the new chip, and, if you are unlucky, the loudspeaker(s) as well!. The lamp limiter, by limiting the available current, saves both the chip and, of course, the speakers. I use a 60 watt lamp initially, and if all seems Ok, a 100watt. But if there is still a problem, it usually reveals itself with the 60 watt. Running equipment up on a Variac is all very well, but it is still "hard" mains, and if anything is wrong, the "unlimited" power available will usually destroy the replaced parts. The variac very rarely gets used when I do this type of repair. Tony Last edited by boxdoctor; 24th Jan 2018 at 12:38 pm.