another tenuously linked question |
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Dave P.
Senior Member Joined: 12 Jan 2015 Location: Northants Status: Offline Points: 5573 |
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To be honest I don't understand what determines the different value requirements of a condenser. Obviously there are reasons for the varying specifications, I just don't know what they are. Going back to the rusty Honda CG 125,I replaced its' condenser with one from a Triumph T'Bird. It worked fine. Will somebody enlighten me please. Thanks.
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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.
1971 V7 Special. 1972 850GT. 1970 T120 Bonnie. 2009 500 Bullet. |
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Mike H
Senior Member Joined: 21 May 2014 Location: East Anglia Status: Offline Points: 8733 |
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The insulation on normal auto wiring is good enough for 1kV. So is the heatshrink sleeving that you could put on over the solder joints. I have so-called bell-wire for wiring up electronic circuits which looks quite thin but actually is spec'd at 1 kV. I have used it in lots of things including valve amplfiers.
No they're not, not at that small value. This is patently obvious by looking at Google pictures. Please do some research before spreading mis-infornation. |
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"Chicken nuggets don't dance on a Tuesday."
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jpc
Senior Member Joined: 06 Oct 2016 Location: Belgium Status: Offline Points: 651 |
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While claiming total ignorance of things electrical, I operate a '71 Fiat 500with a Marelli distributor similar to that on loops, and condenser problems are a regular topic on that other forum.
Posters regularly swear by and recommend this as a much better quality condenser: Edited by jpc - 16 Sep 2018 at 06:33 |
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Jerry atric
Senior Member Joined: 24 Nov 2014 Location: Wiltshire Status: Offline Points: 3367 |
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Thats interesting. Obviously worth paying a bit more and knowing you wont have a problem. I don't understand why Honda bolted the condenser under a cylinder head nut, one of the hottest places surely? Regarding it not being important which way they are connected, does that mean it doesn't matter which wire goes where? (The Jap condensers mostly have 2 wires, 1 to coil, 1 to points) I really wish I understood wiggly amps but I've been trying for fifty years and nothing is sinking in
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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All these "special" or "competition" condensers are merely decent spec condensers which are marketed as "special". If Maplin was still around you could buy one there for pennies and it would probably last far longer than a special automotve one costng far more. To start with they fail due to age, and my guess is that most automotive ones are fairly old stock these days, whereas electronic components will be new. And no, they are not electrolytic.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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jpc
Senior Member Joined: 06 Oct 2016 Location: Belgium Status: Offline Points: 651 |
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Same here, like ballet dancing, if you don't get it by then, I guess you're not meant to All the condensers I've seen are connected to points, and to earth directly via mounting or a wire. |
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jefrs
Senior Member Joined: 12 Aug 2018 Location: West Berkshire Status: Offline Points: 333 |
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You're quite missing the point here. The insulation is not the amount of plastic wrapped around it but the distance the high voltage can jump, which is needs a 'stand off'. If you're building or repairing valve amplifiers as I do with guitar amps, you may well have 450VDC, and the exposed solder contacts have to be separated far enough that the current doesn't jump across. A tiny 1/8 watt resistor cannot take 4kV because the volts will jump and track from one end to the other but a 1/2W resistor is about 13mm long and can. In an amp we have dry air, in the distributor there is usually an oil mist which can lower the spark gap by a factor of between two and ten fold, depending on how messy the distributor is. The coil primary can induce a high voltage at the points, we see a good spark there, the condenser is there to quench the spark, to stop the discharge there so the coil secondary imparts full energy to the spark plug. I've only been messing about with vehicles since the 60s. I've seen and handled hundreds of these things, I so do not need Google. The old school condenser is a small electrolytic, the tin can is a bit of a give away, and the fact that old ones leak the waxy oil out. Back in the day the only type that could take high voltage was an electrolytic, nowadays we have other options, possibly better too. Negative earth is normal now but on really old vehicles you may well find positive earth, which requires a different polarity condenser. Don't try to re-use their condensers.
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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I've only been doing this since the 60s too. Searching around various websites, I have yet to find any reference to an electrolytic being used in this situation, all references being about foil and insulation rolled up. An explanation found. It also contains a method of checking (roughly) that a capacitor is good, but you do need an analogue multimeter.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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iansoady
Senior Member Joined: 23 Jul 2017 Location: Redditch Status: Offline Points: 2402 |
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I still have my old analogue meter and that's about the only thing I use it for. I'm never quite convinced by the test however, and usually play safe with substitution (a bit tricky with a magneto!)
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Ian
1952 Norton ES2 1986 Honda XBR500 1958-ish Greeves/Triumph in progress |
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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The other thing an analogue meter is very good for is checking the tracking of a TPS. Watch the resistance increase or decrease smoothly. Can't do that with digital.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Jerry atric
Senior Member Joined: 24 Nov 2014 Location: Wiltshire Status: Offline Points: 3367 |
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This has gone WAY beyond my understanding now. I just hope my sparking points were down to the condenser. I'm not even going to Google electroiitic
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jefrs
Senior Member Joined: 12 Aug 2018 Location: West Berkshire Status: Offline Points: 333 |
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I have the dubious advantage of being a professional physicist-engineer. I have even had 11kV high capacitance value capacitors made for me for work, operated at 6kV. I can recognise the capacitor type from the construction. Somewhere in a drawer I have a capacitor test meter. The difference here is that it not only tests the leakage but also tells us the capacitor value. Such a meter is a bit specialised use and they tend to be expensive. Surprisingly perhaps, and coming from the physics, the coil itself stores electrical charge, as when the magnetic field collapses that energy is sent down the coil secondary; it's not held in the capacitor. The capacitor only charges up when the points open and stops the points from arcing too much and draining the energy away to ground. When the current stops flowing in the primary coil, high voltage is developed in the secondary coil, which causes the spark at the spark plug. |
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BobV7
Senior Member Joined: 20 Nov 2014 Location: W. Sussex Status: Offline Points: 2740 |
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Another Duracell
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V7 Classic Black and gold was the best. But green & black was nice too. Now blue is in!
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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I really don't need a lecture on how an ignition coil works, that was more than adequately covered in A level physics.. And by the way, I remember making a capacitance tester when I was a teenager. Remember Heathkit?
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Tony-C
Falcone Joined: 18 Aug 2017 Location: Lancashire Status: Offline Points: 67 |
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Remember Heathkit..? I certainly do. . . .It,s me, Ah Cathy, I,ve come ho..ome, I,m so co..o..o..ld. Let me in your window oh.. oh.. oh .." What a great song ..!! Regards, Tony PS, does this qualify as a "tenuous link ..?
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Tony
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