Troubleshooting Christmas Mini-Light Strings

I searched Instructables to be certain I am not covering something someone else has already done, but found nothing.  Here is an excellent article on troubleshooting a bad string of Christmas mini-lights. (I do not know the author and am not connected to him in any way.)  I know of three occurrences of non-working light strings from this year's celebrations. In the first case, the woman who owns the Christmas tree simply bought a new string of lights and hung the new lights over the old string attached at the factory to her synthetic tree. I did not see her tree and cannot say what the cause of the malfunction was. In the second occurrence we put up a synthetic tree with two strings of factory installed lights, one for the bottom half of the tree and one for the top half of the tree. The string on the top half worked some of the time, but then would go out. Typically one suspects a bad bulb. That is also the general suggestion made in the very fine article I linked above. However, that proved not to be the problem. Rather, the problem was the very cheap electrical plug. I cut the plug from the string so I could open it and determine exactly where and how it failed in order to satisfy my own curiosity. Installing a new male plug solved the problem. In the third case, my daughter had a string near the top of her tree that was "out," but not completely at the top. I had limited tools and resources, but plugging the bad string into a different molded female plug brought it back to life. The moral of the story is that while a bad bulb is a frequent source of problems, the molded male and female plugs on these inexpensive light strings are often held together only by a lick and a promise, and fail easily. Giving the molded plugs a hard look is much easier and faster than removing and testing bulb after bulb. The first photo shows an extension cord with molded plugs from three strings plugged into the extension cord. The second photo shows the bad male plug on our tree, and I am using my multi-meter to test for continuity between the brass plug blade and the load end of one of the tiny fuses inside the plug. That part tests "good." The other fuse tested "good," too. In the third photo I inserted a straight pin into the wire and tested for a circuit from the brass blades to the wire. Both sides failed this test.  A multi-meter can easily test what I needed to find this problem. I would have needed to strip away some insulation from the wire or stick a straight pin through the wire to obtain a reading with my multi-meter. But, by this time I had bought a hum tester with a high and a low range for checking different voltage ranges on an AC circuit. It led me to know the plug was the problem. 

Posted by Phil B 5 years ago


Wiring Digital Voltmeter Ammeter Without Shunt

I have this:  http://www.ebay.com/itm/271210262267?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649. They say is can it be used up to 10 amps without a shunt, but I can't find wiring diagram. I am trying to wire into 50 watt led light. I know the small red and black go to power source. I am not sure how to connect 3 thick wires( red, black, yellow) without a shunt. I am only trying to meter 1.5 amp circuit.  Here's what I am trying to wire. Thank you

Posted by flatfish 4 years ago


Help with T5 Fluorescent Light

I'm adding a 9" T5 UV light to a small project I'm making. I found a cheap G6T5 Bulb and a Ballast but when I went to purchase the Sockets for it, I ran into a problem. The Bi-pin T5 sockets come in Shunted & Non Shunted and I have no idea which one I need. What is the difference and how would I tell which one to buy to finish my light? Once I have all this I'll have to figure out how to wire the thing. But first I need to know which sockets I need to buy. THANKS!!

Posted by mrreno 10 years ago


Wind Power Charge Regulators

Hello!! I need some help here...I am very "green" when it comes to alternative energy, so bear with me please! I recently decided to put together a small wind generation system to power my workshop. System is comprised of a 38v Ametek PMDC motor, 6.8' tri-blade array for propulsion. I also intend on installing a 2000 to 3000 watt modfied sine wave inverter powered by my battery bank to provide AC voltage to the shop. I want to be able to used the majority of the power created by my wind generator. I understand the concept of using a "shunt" but do not have a need for hot water or useless lighting. My question is this, would the Flexcharge NC25A charge controller (www.flexcharge.com/flexcharge_usa/products/nc25a/nc25a.htm) be sufficient enough to used in this system? Or is there something else out there that would maintain my battery bank without shunting the load when the bank is fully charged....Thanks in advance.

Posted by NMCBDet23 10 years ago


High Current measurement

I need to measure Current from a welding machine to make a alarm if it goes down below some level for ensuring better quality of welding. The current normally set is of the order of 200A max with around 100V DC.Not sure if i could use some clamp-on meters and pass those values out to Arduino for switching circuit. Shunt resistors may be a better option. But to make a signal conditioner to convert the ma output will be a problem i guess..is there something i can do with Arduino.. any ideas guys....? Thanks in advance Chuppandi

Posted by chuppandi 6 years ago


home made MOT pork chop!

I have a crazy idea to make a transformer for a tesla coil useing two MOTs that are exactly the same, Then cutting them so you only have the 2 "E" core sections, Pull off the primary off one, flip the secondry so its out of phase, put the two cores together and clamp them so they cant move. put some extra shunts in to help limit current, hook up the primary to a variac and turn up the power slowly and test the arc. PORK CHOP! pole pig?

Posted by inductionheat! 9 years ago


Voltage Regulator

EDIT: Anyone Interested please check below posts, this is one is obsoleteHello!I need a voltage smoother and regulator on my circuit(attached below)it is a modified shunt charge controller circuit.It converts the Tri phase alternating current to DC and feeds it into the circuit.The regulator will have to be attachable to the BATTERIES wire in the circuit.It should not consume more than 1v power on its own.My Vout to the battery currently is fluctuating.I will need the to be a stable 12v to charge the batteries. A potentiometer will have to adjust current.I will calibrate current according to my battery bank needs.Led 1 indicates 'charging' Led 2 indicates 'Dump'And Please forgive my circuit diagram design(it looks like crap)but works like gold.Also do NOT suggest huge changes to my controller for the regulator to work. Small suggestions to make it more effective,useful like change the zener diode power rating will be welcome.P.S- Its for my hydro project.Check it out at https://www.instructables.com/community/Help-Hydro-power/Kabir

Posted by mhkabir 9 years ago


A 15 volt Solar panel powering 12 volt dc bilge pump with no battery. How long will it stay working?

I did a little maker faire project to demonstrate how gravitational vortex power plants work. There was no electrical outlet available so I used a 15 watt solar panel to power a 12 volt 600 gallon per hour bilge pump to keep the demonstration running.  During the maker faire numerous people came between the sun and the panel and the thing stopped and restarted no problem.   I would guess that the bilge pump was running at half strength. (It has a 3 amp fuse so that would mean 36 watts is the max it can do?  An electrical engineer and a computer science student both said that I could probably leave the thing connected day and night and the low evening and morning current would not damage my bilge pump (or the solar panel).  It would just start up whenever the light got bright enough. Would anyone like to confirm that? Also, is there any arrangement with capacitors so that even the morning or evening sun will turn the thing (even if slowly) or is there a way to shunt that weak power to something useful (Like electrolysis of sea or  salty water to make bleach) and then go back to the bilge pump whenever the sun is powerful enough again? I would love to know because the project went really well and more could be done with it. Brian

Posted by gaiatechnician 6 years ago


Making a better spot welder....

I am in the process of building a proper spot welder from scratch. Proper more in terms of the electrical and electronics part but not so much in looks ;) My problem now is to find useful info on what power levels are required for certain tasks. I realise that welding thin sheet metal won't need as much time and amps as welding a 3mm stainless steel rod - but what is a "good" power level? I watched a bunch of Youtube videos showing various approaches but for many it seems the producer had no clue about the difference between creating a short with burn marks and a weld... Especially when it comes to creating battery packs with a capacitor bank as the main power provider you can clearly see the device burns holes but does not really create a welded spot. On the other hand there are a few videos showing spot welder made from a MOT that seem to produce a proper melted and welded connection. When I used a proper spot welder at work it had timing settings, power levels and even a feature to adjust how the current rises.... Not to mention a gauge that checks the pressure and only activates the welder once the set point is reached... There is a ton of info out there that after a thausand words still tells you nothing you need to know :( So is there anyone here who can shed some light on the actual process of spot welding in easy words for everyone to follow? I am aiming for a max output of around 400A @ 1.5 -2.5V with an adjustable shunt in the transformer core to avoid oversaturating the core. In a later stage I will add power control over the primary side but until then it is only time control, from a few ms to a max of 5sec if the damn controller arrives one day. Big questions: 1. Is a power control really required or is it possible to cater from thin to thick just by using different timing settings? 2. Since a MOT is used for the power supply: Is it better to leave the shunts out to fully avoid saturation by adding an inductor in line with the primary or is it still better to adjust the shunts under load to get the maximum power possible? 3. Aluminium and other materials benefit from using AC but would be good to have a DC output too, if so then what materials really need DC? 4. All I could find is that copper is used for the electrodes, due to resistance and heat transfer - are there other options apart from using copper? 5. Tricky one: I would prefer to use the secondary winding as the new primary to avoid core saturation and to lower the load on the power outlet. Where can I find very thin copper bar material that I can coil up and insulate as I would quite a few more turns to get at least 1.5V out of it? Just don't like the idea of spending days rolling a copper bar thin enough.... For the advanced model at a much later stage: Of course I would like to be able to use a proper power control instead of a motor dimmer or similar. For obvious reasons an inverter microwave jumps to mind. But after checking one I noticed one big problem: there are not really that many windings on the primary of the transformer at all! Same way our modern switchmode power supplies only use a few turns these things do exactly the same. After some quick and dirty initial tests I realised that even a single turn of thick wire already results in over 20V on the secondary. Wasted a lot of wire and time making one coil with 5 turns less and one with 10 turns less but the system would not even start with it. Seems these things need a fixed inductivity on the primary that matches the frequency used, in my case 36kHz. Would love to overcome this problem so I can at least go down to a single turn to get under 5V on the output side as space is non existing on these inverters. Can I cheat? Do I need to change the circuit to match the new primary coil? Am I thinking in the wrong direction altogether here? And added bonus would be to be able to adjust the power from around 15% to 100%, so far the electronics don't allow anything below 45%. Is it possible to drive these inverters in resonance? (Ok, off topic as I would like to use this for a beefy HV supply) Last thoughts: I know people already used Arduinos and Raspberries with displays and all but so far I have not found anything that shows how to do it properly. Seems all that counts is to create connection one way or the other and to call it a spot weld even if it is just a burn hole from discharging a capacitor bank through a needle like electrode.... For obvious reasons I don't want to create just another spot welder that makes a professional pee himself laughing about it. IMHO nothing beats personal experience with something but I don't really like wasting my time by trying what other people alread did a long time ago. So if YOU already built a MOT based spot welder and used for more than a few spots I would love to hear from you! Let me know what type you used, what problems or shortcomings you noticed or where you feel it just does not work out the way you expected it. From simple things like always getting bad sparks or arcing, over how easy or hard it is to get consistand results to whatever really annoys you while using your homemade spot welder. I hope that your feedback here will help me to write an Instructable on building a spot welder that does what you expect it to do, not once or twice, but everytime you use it. Mechanics might vary the same way the electrode style does but the weld should always be a proper weld that won't tear apart ;)

Posted by Downunder35m 10 months ago