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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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12V fans query
Just as I was blowing out, with a 1KW Martindale, the crud of ages from an
amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#2
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12V fans query
On Tue, 25 Mar 2008 14:47:09 -0000, "N Cook"
wrote: Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. All the fans I've seen were 'brushless' AC polyphase with protection to the driver board (inside the fan) to prevent damage. I suppose if you were reallyi creative you could turn one into an alternator and generate (a small amount) of power with it... g |
#3
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12V fans query
PeterD wrote:
On Tue, 25 Mar 2008 14:47:09 -0000, "N Cook" wrote: Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. All the fans I've seen were 'brushless' AC polyphase with protection to the driver board (inside the fan) to prevent damage. snip Older DC Muffin Fans use DC permanent magnet motors, you can feel magnetic detents as you rotate the blades. Michael |
#4
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12V fans query
"msg" wrote in message ... PeterD wrote: On Tue, 25 Mar 2008 14:47:09 -0000, "N Cook" wrote: Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. All the fans I've seen were 'brushless' AC polyphase with protection to the driver board (inside the fan) to prevent damage. snip Older DC Muffin Fans use DC permanent magnet motors, you can feel magnetic detents as you rotate the blades. They all have permanent magnet motors, but they're brushless. You can feel detents on those too. |
#5
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12V fans query
On 3ÔÂ25ÈÕ, ÏÂÎç10ʱ47·Ö, "N Cook" wrote:
Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list onhttp://home..graffiti.net/diverse:graffiti.net/ Do you want access to China's massive pool of electronic manufacturers... but lack the time to contact suppliers, negotiate contracts, arrange shipping or monitor product quality? Don't worry - Let seriouswholesale deal with all that for you. *Check out the huge range of Gadgets, MP3 / MP4 Players, Car DVD / Audio, and Computer Accessories now by visiting the online wholesale catalog at seriouswholesale. com You'll have peace of mind thanks to the seriouswholesale Quality Control, 12-month Warranty on all products, and easy secure payment by credit card through Paypal. Selling on eBay or your own online store? Send products direct from our warehouse to your customers using our unique drop-shipping service. You can profit by selling hundreds of different products, without holding any of your own inventory! Any questions you have will be answered by the seriouswholesale English-speaking customer support team... Their aim is to make your China electronics importing business easier to run than ever before. Welcome to http://www.seriouswholesale.com. seriouswholesale - Buy from the source, profit without the hassle. - 12 Months Warranty - No minimum order restrictions - Drop-shipping with no additional fee - Pay by safely by PayPal seriouswholesale Wholesale Co., Ltd.: Chinas original and best online electronics wholesaler & drop-shipper: seriouswholesale. com |
#6
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12V fans query
Meat Plow wrote in
: On Tue, 25 Mar 2008 14:47:09 +0000, N Cook wrote: Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. I've never given it a second thought. Nor have I ever damaged anything by it. As a young lad I loved to turn my bicycle upside down and turn the garden hose on the pedals and wheels and watch them spin. I was having problems with my car. Was in a small town garage watching while the guy removed the noisy wheel bearing from my front wheel. He washed it a couple of swishes in solvent and grabbed the pressurized air hose. As he started to blow the solvent out, the bearing started to spin. It sounded like a warning siren. Within a few seconds, it went 'BANG' and roller bearings ricochet around the garage like bullets. He yelled and started to nurse a sore hand. His boss came out and explained to him why he should never do that. (I think he had already learned the lesson.) Well, I needed new wheel bearings, anyway. -- bz please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set. |
#7
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12V fans query
I used to turn my bicycle upside down and spin the devil out of the rear
wheel and then slam on the brake.I own a 1961 made in Germany moped with sixteen original miles on it, it has bicycle pedals on it. You can rig up an old computer hard drive motor if you want to make your own wind speed aeronometer.I saw how to do it on the internet. cuhulin |
#8
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12V fans query
On Tue, 25 Mar 2008 11:04:22 -0400, PeterD put
finger to keyboard and composed: On Tue, 25 Mar 2008 14:47:09 -0000, "N Cook" wrote: Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. All the fans I've seen were 'brushless' AC polyphase with protection to the driver board (inside the fan) to prevent damage. I suppose if you were reallyi creative you could turn one into an alternator and generate (a small amount) of power with it... g Brushless DC fan motors use integrated Hall effect sensors/ICs for electronic commutation. See these datasheets for examples: http://www.anpec.com.tw/products/dow.../APX9141a7.pdf http://www.anpec.com.tw/products/dow.../APX9140a8.pdf These ICs have integral reverse voltage protection, as you have said. Here is a more elaborate example: http://web.archive.org/web/200605151...01/02/FIG2.JPG I'm wondering how the EMF produced by the motor windings can generate a current that passes through the switching elements, either in the form of discrete transistors or internal to the commutator IC. I suppose that in the latter example the current could flow through the diodes. As an experiment, I suppose you could attach two fan rotors back-to-back with a suitable spacer (eg velco?) and use one fan to drive the other. - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
#9
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12V fans query
Meat Plow wrote: On Tue, 25 Mar 2008 19:34:24 +0000, bz wrote: Meat Plow wrote in : On Tue, 25 Mar 2008 14:47:09 +0000, N Cook wrote: Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. I've never given it a second thought. Nor have I ever damaged anything by it. As a young lad I loved to turn my bicycle upside down and turn the garden hose on the pedals and wheels and watch them spin. I was having problems with my car. Was in a small town garage watching while the guy removed the noisy wheel bearing from my front wheel. He washed it a couple of swishes in solvent and grabbed the pressurized air hose. As he started to blow the solvent out, the bearing started to spin. It sounded like a warning siren. Within a few seconds, it went 'BANG' and roller bearings ricochet around the garage like bullets. He yelled and started to nurse a sore hand. His boss came out and explained to him why he should never do that. (I think he had already learned the lesson.) Well, I needed new wheel bearings, anyway. LOL great story. I blew the rear end out of my 70 Dodge Charger R/T at a drag strip when I was kid. A couple of the bolts that hold the ring gear to the carrier blew right through the cover. Luckily nobody was standing behind me. An Army buddy and I decided to head to Florida on a long weekend. We got about 50 miles from Ft. Rucker when he threw a connecting rod, and sent the piston through the oil pan. I found the piston about 150 feet away with part of the sheared wrist pin and broken rod bolted to one side. I took it back to the barracks and cleaned it up, and removed the piece of the connecting rod. If you were careful, you could balance it on the desk, on the one good surface. The next day we had some smart ass sergeant along with the captain for Monday morning inspection. The Sergeant grabbed it up and started yelling, demanding to know what it was, and why it was on my desk. The captain had a big grin on his face, so I smiled and told the jerk "It's a hemorrhoid extractor, would you like me to demonstrate it on you?" He stormed out of the room, while the Captain struggled to keep from laughing at him. -- aioe.org is home to cowards and terrorists Add this line to your news proxy nfilter.dat file * drop Path:*aioe.org!not-for-mail to drop all aioe.org traffic. http://improve-usenet.org/index.html |
#10
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12V fans query
On Wed, 26 Mar 2008 06:41:05 +1100, Franc Zabkar
wrote: On Tue, 25 Mar 2008 11:04:22 -0400, PeterD put finger to keyboard and composed: On Tue, 25 Mar 2008 14:47:09 -0000, "N Cook" wrote: Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. All the fans I've seen were 'brushless' AC polyphase with protection to the driver board (inside the fan) to prevent damage. I suppose if you were reallyi creative you could turn one into an alternator and generate (a small amount) of power with it... g Brushless DC fan motors use integrated Hall effect sensors/ICs for electronic commutation. See these datasheets for examples: http://www.anpec.com.tw/products/dow.../APX9141a7.pdf http://www.anpec.com.tw/products/dow.../APX9140a8.pdf These ICs have integral reverse voltage protection, as you have said. Here is a more elaborate example: http://web.archive.org/web/200605151...01/02/FIG2.JPG I'm wondering how the EMF produced by the motor windings can generate a current that passes through the switching elements, either in the form of discrete transistors or internal to the commutator IC. I suppose that in the latter example the current could flow through the diodes. I wasn't clear, I was thinking rip out the electronics in there now and add rectifiers... As an experiment, I suppose you could attach two fan rotors back-to-back with a suitable spacer (eg velco?) and use one fan to drive the other. - Franc Zabkar |
#11
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12V fans query
I wasn't clear, I was thinking rip out the electronics in there now and add rectifiers... It works. A hard drive spindle motor also makes a decent miniature 3 phase AC generator. You can even wire one up to another similar motor and it will run, just like a regular 3 phase motor. |
#12
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12V fans query
When anybody ask me about what something is for, I tell them it's a
windshield wiper for a billygoat's a.. You should never spin a dry bearing.One dry spin can ruin that bearing, and often does. cuhulin |
#13
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12V fans query
Indeed this is true for modern versions, but DC Muffin fans from the 1960s had brushes (electronic comutation would have been large and of prohibitive expense). They had DC muffin fans in the 60s? I don't recall ever seeing one, what were they used in? I've seen AC muffin fans powered by shaded pole motors, and a few DC fans that were just a fan blade stuck on the end of a little DC motor, but I've never come across one I'd call a muffin fan. |
#14
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12V fans query
James Sweet wrote:
"msg" wrote in message ... PeterD wrote: On Tue, 25 Mar 2008 14:47:09 -0000, "N Cook" wrote: Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. All the fans I've seen were 'brushless' AC polyphase with protection to the driver board (inside the fan) to prevent damage. snip Older DC Muffin Fans use DC permanent magnet motors, you can feel magnetic detents as you rotate the blades. They all have permanent magnet motors, but they're brushless. You can feel detents on those too. Indeed this is true for modern versions, but DC Muffin fans from the 1960s had brushes (electronic comutation would have been large and of prohibitive expense). Michael |
#15
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12V fans query
msg wrote in
: James Sweet wrote: Indeed this is true for modern versions, but DC Muffin fans from the 1960s had brushes (electronic comutation would have been large and of prohibitive expense). They had DC muffin fans in the 60s? I don't recall ever seeing one, what were they used in? I've seen AC muffin fans powered by shaded pole motors, and a few DC fans that were just a fan blade stuck on the end of a little DC motor, but I've never come across one I'd call a muffin fan. I knew you'd ask My recollections are from govt. contract gear that used 24 or 28 VDC fans. These may not have been "Muffin" brand fans but I am unable to inspect one any more as the gear is long gone. Anyone else with these recollections? One remarkable fan that I wish I still had was the 400 Hz "Minicube" blower; about one inch on a side, it could easily levitate or blow itself off of the bench under power. These were used on F111A avionics boards (and no doubt other platforms as well) Michael I salvaged and ratholed some 12V fans from PC power supplies,and after Hurricane Charlie knocked out power,I used two of them with a 12V/20 A-H SLA battery to give me some quiet air circulation at night so I could sleep in the 90+ deg temps. It was just enough to make me comfortable. I also had a 8-AA cell 12v fluorescent lamp that I made an ext.power cable to connect to a 12v SLA or car battery for lighting. I was without power for 7 days. -- Jim Yanik jyanik at kua.net |
#16
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12V fans query
James Sweet wrote:
Indeed this is true for modern versions, but DC Muffin fans from the 1960s had brushes (electronic comutation would have been large and of prohibitive expense). They had DC muffin fans in the 60s? I don't recall ever seeing one, what were they used in? I've seen AC muffin fans powered by shaded pole motors, and a few DC fans that were just a fan blade stuck on the end of a little DC motor, but I've never come across one I'd call a muffin fan. I knew you'd ask My recollections are from govt. contract gear that used 24 or 28 VDC fans. These may not have been "Muffin" brand fans but I am unable to inspect one any more as the gear is long gone. Anyone else with these recollections? One remarkable fan that I wish I still had was the 400 Hz "Minicube" blower; about one inch on a side, it could easily levitate or blow itself off of the bench under power. These were used on F111A avionics boards (and no doubt other platforms as well) Michael |
#17
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12V fans query
msg wrote: James Sweet wrote: Indeed this is true for modern versions, but DC Muffin fans from the 1960s had brushes (electronic comutation would have been large and of prohibitive expense). They had DC muffin fans in the 60s? I don't recall ever seeing one, what were they used in? I've seen AC muffin fans powered by shaded pole motors, and a few DC fans that were just a fan blade stuck on the end of a little DC motor, but I've never come across one I'd call a muffin fan. I knew you'd ask My recollections are from govt. contract gear that used 24 or 28 VDC fans. These may not have been "Muffin" brand fans but I am unable to inspect one any more as the gear is long gone. Anyone else with these recollections? I had one out of a military radio or test set that was 24 VDC. It was about 1.5" square, and about 2.75" deep. It was a regular brush motor, about the size of the early dust buster with a regular fan blade. One remarkable fan that I wish I still had was the 400 Hz "Minicube" blower; about one inch on a side, it could easily levitate or blow itself off of the bench under power. These were used on F111A avionics boards (and no doubt other platforms as well) The GRC-106 used them, too. I had a handful of ones pulled for noisy bearings at the CE plant where we built the 106. -- aioe.org is home to cowards and terrorists Add this line to your news proxy nfilter.dat file * drop Path:*aioe.org!not-for-mail to drop all aioe.org traffic. http://improve-usenet.org/index.html |
#18
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12V fans query
Jim Yanik wrote:
snip I salvaged and ratholed some 12V fans from PC power supplies,and after Hurricane Charlie knocked out power,I used two of them with a 12V/20 A-H SLA battery to give me some quiet air circulation at night so I could sleep in the 90+ deg temps. It was just enough to make me comfortable. I also had a 8-AA cell 12v fluorescent lamp that I made an ext.power cable to connect to a 12v SLA or car battery for lighting. When I lost power some many years ago, I got six 200 AH deep cycle 12V marine batteries (factory cosmetic seconds) to power a Sola 2.5KVA UPS which I wired into the breaker panel, first disconnecting the utility service. To charge the batteries I mated a 10 HP Briggs horiz. shaft engine to an old military DC generator set; it's duty cycle was governed by the batteries' specific gravity. The power was cleaner than what I normally had and the UPS was continuous duty rated Michael |
#19
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12V fans query
Deep cycle batteries are not suppose to be drained more than half way
down.More than that shortens the life span of those batteries. cuhulin |
#20
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12V fans query
As an experiment with no load other than DVM , neg to neg, 12V dc , 0.2A fan
, 1 foot from the nozzle of a 1KW fan then 17volt output from the fan I tried.. Must have contained segmented magnets. Turnuing the fan the other way in the airstream still produced "positive" voltage. I didn't try it any closer. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#21
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12V fans query
wrote in message ... Deep cycle batteries are not suppose to be drained more than half way down.More than that shortens the life span of those batteries. cuhulin That rather depends on the construction of the plates in the battery, which determine whether or not it is a genuine deep cycle battery, which is good to 20%, or a sponge plated hybrid which is labelled "deep cycle", but is only good, as you say, to 50% if you want a long life. Genuine marine quality deep cycle batteries, as Michael suggested he was using, should be of the former variety. The latter tend to be general leisure batteries, as far as I know. Arfa |
#22
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12V fans query
On 3ÔÂ25ÈÕ, ÏÂÎç10ʱ47·Ö, "N Cook" wrote:
Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list onhttp://home..graffiti.net/diverse:graffiti.net/ Do you want access to China's massive pool of electronic manufacturers... but lack the time to contact suppliers, negotiate contracts, arrange shipping or monitor product quality? Don't worry - Let seriouswholesale deal with all that for you. *Check out the huge range of Gadgets, MP3 / MP4 Players, Car DVD / Audio, and Computer Accessories now by visiting the online wholesale catalog at seriouswholesale. com You'll have peace of mind thanks to the seriouswholesale Quality Control, 12-month Warranty on all products, and easy secure payment by credit card through Paypal. Selling on eBay or your own online store? Send products direct from our warehouse to your customers using our unique drop-shipping service. You can profit by selling hundreds of different products, without holding any of your own inventory! Any questions you have will be answered by the seriouswholesale English-speaking customer support team... Their aim is to make your China electronics importing business easier to run than ever before. Welcome to http://www.seriouswholesale.com. seriouswholesale - Buy from the source, profit without the hassle. - 12 Months Warranty - No minimum order restrictions - Drop-shipping with no additional fee - Pay by safely by PayPal seriouswholesale Wholesale Co., Ltd.: Chinas original and best online electronics wholesaler & drop-shipper: seriouswholesale. com |
#23
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12V fans query
On 3ÔÂ25ÈÕ, ÏÂÎç10ʱ47·Ö, "N Cook" wrote:
Just as I was blowing out, with a 1KW Martindale, the crud of ages from an amp and its fans. Thought - these fans act as DC generators if blown forcefully. Presumably you could damage, if driving negative volts into ps or fan contol circuit. Next time I will jam something in the blades before zapping one with 1KW of draught. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list onhttp://home..graffiti.net/diverse:graffiti.net/ Do you want access to China's massive pool of electronic manufacturers... but lack the time to contact suppliers, negotiate contracts, arrange shipping or monitor product quality? Don't worry - Let seriouswholesale deal with all that for you. *Check out the huge range of Gadgets, MP3 / MP4 Players, Car DVD / Audio, and Computer Accessories now by visiting the online wholesale catalog at seriouswholesale. com You'll have peace of mind thanks to the seriouswholesale Quality Control, 12-month Warranty on all products, and easy secure payment by credit card through Paypal. Selling on eBay or your own online store? Send products direct from our warehouse to your customers using our unique drop-shipping service. You can profit by selling hundreds of different products, without holding any of your own inventory! Any questions you have will be answered by the seriouswholesale English-speaking customer support team... Their aim is to make your China electronics importing business easier to run than ever before. Welcome to http://www.seriouswholesale.com. seriouswholesale - Buy from the source, profit without the hassle. - 12 Months Warranty - No minimum order restrictions - Drop-shipping with no additional fee - Pay by safely by PayPal seriouswholesale Wholesale Co., Ltd.: Chinas original and best online electronics wholesaler & drop-shipper: seriouswholesale. com |
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