| Author |
Message |
    
miro forest
Senior Member
Username: miro
Post Number: 521
Registered: 11-2001
| | Posted on Saturday, November 06, 2010 - 06:58 pm: | 
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Here's a video note about an inductor for the M&B ignition.
I tried it out on a 12 V battery and you get a whopping blue spark. I think it could probably work OK for much lower voltage batteries eg 6 V
http://www.youtube.com/watch?v=Wv2fjppXUT0
Miro |
John Davis
Senior Member
Username: johnny
Post Number: 360
Registered: 03-2006
| | Posted on Sunday, November 07, 2010 - 07:55 am: |
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Miro,
Thanks for posting the video very informative. You are using this as a low tension coil for a ignitor engine correct?
I have been using the clutch coils out of old automotive air conditioning compressors. They are small compact and do not weigh much. This is the coil located inside the pulley on the air conditioning compressor. The pulley can be difficult to remove but once you have done a few it's not to bad. The coils normally check around 3 or 4 ohms and give a good blue spark. If you know someone that works on cars or trucks they probably have a few old worn out air conditioning compressors laying around they will give you. I'll post some photos when I get a chance. |
John Davis
Senior Member
Username: johnny
Post Number: 361
Registered: 03-2006
| | Posted on Sunday, November 07, 2010 - 11:08 am: |
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Here's a few photos of the air-conditioner compressor clutch coils and also the type of rechargeable battery I like to use. The battery works fine for running engine at the shows but not sure how long it would last on marine engine in a boat running all day. You can charge the battery with a regular 12 volt DC, 2 amp trickle charger. The photos of the coils are very close to actual size of the coils. Easy to mount anywhere just put a steel plate or bar over the front with a small hole for a long wood screw. One thing I have learned over the years with the ignitor engines and low tension coils. If you use a coil that has to low of resistance or Ohms the points on the ignitor will not last very long (Burn-up). I like to have at least 3 Ohms or higher.
First coil checks 4.5 ohms.
second coil checks 4 ohms.
12 volt DC, 7 amps
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miro forest
Senior Member
Username: miro
Post Number: 523
Registered: 11-2001
| | Posted on Sunday, November 07, 2010 - 05:49 pm: |
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I have checked several of the primary coils on the microwave oven transformer.
They are around 0.5 Ohms.
That means, based on John's note, that running these coils on 12V wouldn't be good for the points.
So, either use a lower voltage battery (3 V might still work OK), or put a 2 or 3 Ohm resistor in series with the coil.
The resistor should have a power rating of 10 watts, so it will likely be a wire wound resistor.
The advantage of using the resistor, is that you could remove it from the circuit as the battery voltage declines, and thus get home.
miro |
Ernie
Senior Member
Username: ernie
Post Number: 1287
Registered: 01-2002
| | Posted on Monday, November 08, 2010 - 08:08 am: |
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Just use a small alternator rotor and 12 volts.
Low amp draw and a huge arc.
7 amps is really kind of high for ignitor points.
The one I use draws 3 amps. There are pics and specs on here somewhere. Also the A/C clutch would work a lot better if it had a soft iron core. |
John Davis
Senior Member
Username: johnny
Post Number: 364
Registered: 03-2006
| | Posted on Monday, November 08, 2010 - 11:27 am: |
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The A/C clutch coil is in-cased in steal. We have been using them for years now with no problems. I think most of the old original ignitor coils had nothing more then a wooden dowl or block in the center. |
John Archibald
Senior Member
Username: john_archibald
Post Number: 155
Registered: 08-2006
| | Posted on Monday, November 08, 2010 - 11:47 am: |
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Yah, and they were wound with wooden wire, too.
Archibald
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Ernie
Senior Member
Username: ernie
Post Number: 1289
Registered: 01-2002
| | Posted on Monday, November 08, 2010 - 08:52 pm: |
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Old make and break coils have a soft iron core made of many strands of iron wire about 16 awg. They also were NOT made to operate on 12 volts. They draw about 9 amps which is way too much for a set of ignitor points. They were made to operate on 6 volts from dry cells. Also if the engine stops with the points closed with 12 volts things get pretty hot real quick. I use my old coils for display.
The soft iron core helps create a large arc. Just for kicks why don't you try putting some kind of iron core in the center if one of your A/C clutch coils.
Hope this helps
Ernie |
John Davis
Senior Member
Username: johnny
Post Number: 365
Registered: 03-2006
| | Posted on Monday, November 08, 2010 - 09:53 pm: |
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Sorry, I was wrong about the wooden dowel. some were made with a iron or steel pipe with a bolt through the middle with wood end caps. Copper wire around the pipe. I never claimed to be an electronic coil expert. Just thought that someone might like to know about using the air conditioning clutch coils to run their engine. |
Ernie
Senior Member
Username: ernie
Post Number: 1290
Registered: 01-2002
| | Posted on Tuesday, November 09, 2010 - 07:40 am: |
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John,
Any way to get a good easy to use M&B coil is good. Like I said I keep my old coils for display as it is hard to find a good one. The wood parts split easily. Also using a tall short coil like an A/C clutch magnet or alternator rotor that will work good on 12 volts and is easy on the ignitor points seems to me to be a good thing.
As to tall and short the magnetic field colapses much quicker in this type of coil. (more efficient and better arc) Note how most of the old stationary generators and alternators were made.
The old M&B coils are long and thin which isn't an issue due to low engine RPM but still not as efficient as a tall short one.
I am curious if you get a chance what putting an iron core in one does to the intensity of the arc.
Hope this helps
Ernie |
