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Thread: Power feed buy new or repair?
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8th Nov 2019, 09:32 AM #61Most Valued Member
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Yea I have wated that video from that Babajan channel. Very interesting. I did notice that he two strands, called bifilar winding?
He certainly makes it look easy. Probably does a nice job and gets paid stuff all for making 50 a day!
Some takeaways for me on that are the former sizing method, the use of superglue and the use of that former paper. Is that a special type of paper or can I just use some heavy paper from office works?
Actually, I'm not sold on the use of paper. I think that some cotton warp, maybe 1/2" wide may do a better job and keeping in tight. However it's also going to make it bulkier too I guess.
Hope my scales come today.
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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8th Nov 2019, 01:51 PM #62Senior Member
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Transformer paper
https://new.abb.com/products/transfo...sulation-paper
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8th Nov 2019, 07:58 PM #63
Hi Guys,
I used to have several rolls of paper like that, not having any real use for them they got thrown away, along with hundreds of reels of enamelled and cotton covered Litz wire that went to the scrap yard ! I regret not keeping any. Though I do wonder what it would have been worth today.
One other point that I found interesting in the videos was the use of varnish that he just poured over the windings, I thought that it could become very messy even though he did use a drip tray.Best Regards:
Baron J.
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12th Nov 2019, 08:05 PM #64Most Valued Member
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Ok. Scales arrived today.
I weighed the field windings after removing the 30 turns of the heavier wire.
I parted and cut a random amount of the windings, weighed it and proceeded to count.... all 331 turns. 331 turns weighed 6.10g.
The entire coil weighed 46.54g.
That means approx 2500 turns of 0.125mm ecw, not including the 30 turns of 0.75mm ecm at each end.
A $300 power feed is starting to look attractive....
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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12th Nov 2019, 09:57 PM #65
Hi Simon,
That wire at 0.125 mm diameter, sounds like 16 AWG , take off a bit for the enamel and you get 18 AWG which is about 6.5 Ohms per 1000 feet, times 2.5 = 17 Ohms. that seems a little low to me !
I would have expected nearer to 50 or 60 Ohms. You could easily salvage that from an old wall wart !Best Regards:
Baron J.
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13th Nov 2019, 09:23 AM #66Most Valued Member
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Hi Baron,
I'm confused. At 0.125mm I thought that would be 36 awg wire.
This has a mass of 0.076 lb/1000 ft.
That's 34.47g / 1000 ft (please excuse my mixed metric/imperial units)
At 46.54g that means 1350 ft of field winding.
36 awg wire is quoted at 445 ohm / 1000 ft.
That equates to a dc resistance of 600 ohms per winding.
Given I measured a resistance of 1.2k it seems about right?
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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13th Nov 2019, 02:51 PM #67
Hi Simon,
I have me confused too ! I've obviously looked at the wrong value and got the resistance value wrong.
0.12 mm is 36 AWG, you are right it is around 415 Ohms per 1000 feet.
So your 600 Ohms figure is in the ball park.
The tables that I used were from the ARRL handbook, but I found this on line
https://www.rapidtables.com/calc/wir...uge-chart.html
Whilst not identical the calculator is OK.
I'll measure a couple of wall wart transformers later, because I'm sure that could be a cheap source of wire.
*****************************************
OK ! I've measured several. The highest reading I got was 650 Ohms primary and that was a 5 volt 1 amp DC output
and the lowest was 120 Ohms primary and 24 volt 1 amp DC output. There were various readings from several others between those two values, having output voltages between 5 and 24 volts all having output currents between 0.5 amps and 1.2 amps.
I also measured a shaded pole fan motor with a winding resistance of 160 Ohms.
Based on these measurements I'm not convinced that 600 Ohms is correct.Last edited by BaronJ; 14th Nov 2019 at 07:14 AM. Reason: Added data
Best Regards:
Baron J.
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15th Nov 2019, 08:52 AM #68Most Valued Member
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Thing is, before I took the field windings apart, I measured the DC resistance as approx. 1.2K yet I couldn't get the motor working.
I'm still confident that my sample measurement and extrapolation of results has yielded a sensible result for the number of turns though. Not sure where I could have gone wrong with my calculations?
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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15th Nov 2019, 08:35 PM #69
Hi Simon,
Basic Ohms law says that 110 volts / 1200 Ohms = 0.090 ma. 110 volts x 0.090 = 10 watts.
I would have expected more than that, particularly since the armature resistance is so low !Best Regards:
Baron J.
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16th Nov 2019, 09:03 PM #70
Hi Simon,
As you will know I've been measuring the winding resistance of a few transformers and the like recently. Well today I decided to have a look at an old microwave oven transformer. I measured the high voltage winding at several thousand ohms. Breaking off one end of the wire, I've discovered that it measures 12 thou diameter. Using the tables on
Wire gauge size chart | AWG table
That tells me it is 36 SWG and 414 Ohms per 1000 ft. So 110v / 414 Ohms = 0.265 Amps. About 30 Watts.
These transformers are readily available and fairly easy to strip the windings off, so that would be a cheap source of suitable wire.
Let me know what you think !Best Regards:
Baron J.
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17th Nov 2019, 10:02 AM #71Most Valued Member
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Hi Baron,
I really appreciate your continued help with this.
I found this on ebay, at $12 including free delivery I thought it was a reasonable gamble.
https://www.ebay.com.au/itm/Enamelle...rJOAy1vkbwr6DQ
I would have prefered the 900M roll but it's out of stock. In any case, the coil weighed 46g (including 40 years of crud and bit of varnish) so a 50g roll for each coil should do the trick.
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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17th Nov 2019, 10:34 PM #72
Hi Simon,
Yes that would do the job, nice that its solder through as well !
As you know am all for salvage and reuse ! The microwave transformer as a doner source of wire would be much cheaper and throw away if you make a mess of it.
OK you would have to mess about a bit to remove the winding, but there is enough on them to wind several coils.
I've already come up with a design for a winding jig that would let you wind both coils at one time based on the weight of the wire, rather than counting turns. You would however have to wind two spools of wire first from the transformer. A piece of cardboard postal tube will do.
Run enough wire to get say 40 - 45 grms on to half the tube, put a cardboard spacer on the tube to keep the wires separated and then wind another 40 grms on the other side. This will give you two known weights of wire. These will then wind two virtually identical windings. Simply wind on until the weight is about right, as I have said, its not critical.
HTH.Best Regards:
Baron J.
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22nd Nov 2019, 08:39 AM #73Most Valued Member
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Hi Baron,
Yep Im with you. I really get a kick out of re-purposing stuff.
However, I have looked (mainly on eBay) for both new and S/H high voltage microwave transformer/power supplies and can't find any for cheaper than the copper wire I linked above.
OK if I happen to find one of the naturestrip as can happen from time to time but they are never around when you actually need one!
Got some other stuff on atm and my wife has started a new job in a completely different industry after 19 years in her old job. So things take time to get back into a "normal" routine.
I think I'll purchase that ecw anyway and having it waiting when I get a chance.
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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22nd Nov 2019, 03:52 PM #74Most Valued Member
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What a co-incidence!
Was at school assembly today for school pickup. Talking to one of the mums that I know well, we got onto the conversation that included her telling me that she just bought a new microwave oven. Asked what she did with the old one.... she still has it. Looks like I have actually scored a free microwave oven for parts!
Less than 8 hours after my last post telling you that I can't find one for cheap! Funny hey?
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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22nd Nov 2019, 10:03 PM #75
Hi Simon,
Glad you managed to find one ! Those transformers can be very useful, not just for salvaging the wire from the transformer, but for other things ! Such as a spot welder ! Also there are some useful parts in there. But no way buy an old one ! I've had a couple just thrown over the back gate that I've stripped bits from and kept. Unfortunately the newer transformerless, inverter ones are not worth bothering with unless you want the micro switches. You can easily tell the difference because the good ones are very one side heavy, the transformer being behind the control panel.
If you see one dumped, pick it up ! I certainly wouldn't pass one up !
Once you have your transformer, very carefully cut the laminations away without damaging the wire, so that you can push the winding off the bottom of the core. At this point you can now find the end of the wire. Usually the spade connector is the place to start, as this is usually secured by tape holding it down.
Now use a cardboard postal tube or similar to wind on two piles of wire of about the same weight. Weigh the lot, so that you know how much weight you have. The actual weight doesn't matter as long as it is greater than the total weight of wire than you need. When you come to do the actual motor windings, you will be winding two coils at the same time so they will be identical. Now all you have to do is weigh the donor wire to work out the weight of wire you have wound onto the winding jig.
As far as a winding jig is concerned, four 3" inch nails and some plywood, a length of all thread.
Drill four holes in three suitable pieces of ply to suit the original winding corners, so that the nails will be a firm push fit. Make two spacers to fit over the all thread to separate the cheeks by the winding width. Clamp the lot together with nuts and washers so that you can spin it in the lathe.
Hope all this makes senseBest Regards:
Baron J.
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