Instrument to detect presence of AC voltage

Hi everyone, hope the new year finds all in great health & spirit.
I have a very simple question, which arises each year as I try to pack away,
until next year, all the Christams strings of mini lights.
As usual several strings of series wired lights are not working.
By carefully examining each light filament using a x4 power loupe, I have managed to find & replace, most of the faulty bulbs causing problems.
Unfortunely this method is not reliable, & I still have a string of 100 mini lights, refusing to either light up, or submit their fault secrets to the above approach. I gather their are instruments capable of picking up the presence of 110/240 VAC. If I could find such an instrument suitable for this repair task, I would be a happy chappie.
BTW I am aware of a special purpose instrument designed for mini light repairs, however availability & price are issues for me in Queensland Australia where there is no manufacturers agent.
Hence my wish to use a simpler more "all purpose " device, can anyone help with a specific model/brand recommendation & source for 240 V version.
Rgds again to all, Peter O
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peterlonz wrote:

Any number of things will work.
An off-tune AM radio moved along the string (when it is plugged in). Or with a mains/stud/pipe detector on mains(eg www.maplin.co.uk YP30H ) etc..
--
Sue

YP30H

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Christmas tree lights are pretty much a disposable item these days...Just buy new ones every year or three and you can avoid the holiday frustration....Ross
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On 1/5/06 4:00 PM, in article Tqivf.192680$ snipped-for-privacy@news-server.bigpond.net.au, "peterlonz"

A capacitor in series with an ac voltmeter will do he job. But that is not the way to do it.
Most digital multi-meters today have an ohm-meter function. Even better, it may come with a buzzer function. I would just use that to check for conductive continuity.
Bill
-- Ferme le Bush
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wrote:

There are devices available. One put out by Carillon (try carilloncanada.com) is called "LiteTester Plus" (about $10 CDN) It comes with batteries included. I got it at the local hardware store (Home) where it was in the Xmas light display area. It is fairly cheap and will test bulbs and indicate broken or loose connections. I have used it and it does make the job much easier than trying to test each bulb and section of wiring with a multimeter. However, on a long string in two independent sections as a 100 bulb string is likely to be, it did not help me where one section has failed. This may be due to the specific nature of the string- which is now in the trash as replacement sets are cheap and my remaining life time can be spent on more interesting things. There is at least one version of this which is a bit more expensive but may be better but I intend to gradually replace all with LEDs as they become cheaper.
--

Don Kelly @shawcross.ca
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Here is a site which shows the device that I have. http://home.howstuffworks.com/question270.htm
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Don Kelly @shawcross.ca
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Don Kelly wrote:

They detect the "alternating electromagnetic waves"? Simpler to say they detect the electric field on a hot wire. The reference for the detector is through the user to ground so they don't detect on neutrals. These are made by a bunch of manufacturers for general use and are handy. You need to know which end of the string has the hot feed and separate the lamp wire out from the other wires so you don't detect them. If both sides of a lamp are dead move toward the hot end, else the neutral end. Clever idea; would have saved a lot of grief if I would have known it long ago. The detector from ehsjr appears to be the same kind of detector with added functions.
bud--
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No need to separate the lamp wire- point it at the upper end of the socket as per instructions.
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Don Kelly @shawcross.ca
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One of my problem is that I found the gadget in a drawer without instructions, thus a lot of guesswork. MG
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The explanation on how the tester works is not convincing. It asserts that the tester senses the EM wave of a conductor carrying power. Bad wording but let'say the tester picks up the magnetic field since it appears to have a loop. In a series string with a open light the current is zero on the entire string. All lights good and bad have no current until you fix all the bad one.
Some string have bulbs with a bypass that seems to short the bulb when it fails open. Bad bulbs are easy to find, they are the one not shining.
On the other hand the explanation say you can find wires in the wall and whether a socket has power, implying that it senses the E field. This techniques may work in principle if we assume that all good bulbs connected to the line side have a 120V signal, and all the good bulb connected to the neutral have zero signal. The bad bulb has 120V across and is the one in between.
I have a tester just like the picture and have not been able to make use of it.
I spent a day fiddling with this problem because I had a bed string intimately wrapped around a motorized wing flapping Angel and replacing the string was not an easy alternative.
I tried, unsuccessfully, to build a simple capacitive coupled sensor like a 5 inch dipole connected to a MM. Trying to detect a different reading between the Hot side of the fault and the Cold side but no reliable reading correlating with the fault.
LED seems to be the only solution, but when they will be popular Wall Mart will have the design so cheapened up that will still last only 1.3 seasons on average.
MG
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peterlonz wrote:

For the device you are talking about, see Jaycar catalog number QP2260
Like the others, I would not try to use that device for testing your xmas lites. Aside from the fact that it would probably be ineffective for that, its a lot safer for you to use an ohmmeter.
Ed
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Using an Ohm-meter requires to: Remove lamp - not easy to do, requires player or blade or finger nail. Ohm out the lamp - not easy to do with two hands easy with three hands Put the lamp back - easy Repeat 100 times or so - sum of the above Unless the problem is with the socket connection in which case after unplugging and plugging 100 bulbs you have increased the probabilities of having one more open.
The whole idea is to have a contactless method.
MG
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MG wrote:

You can find the bad bulb in seven or eight measurements with the ohm meter; you don't need 3 hands; and the op's question asking for a specific "all purpose" device was answered: " Hence my wish to use a simpler more "all purpose " device, can anyone help with a specific model/brand recommendation & source for 240 V version. "
If you have something that would help the OP, I'm sure we would be glad to read it.
Ed
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