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Searcher
Senior Member
Username: searcher
Post Number: 414
Registered: 10-2004
| | Posted on Wednesday, February 10, 2010 - 02:27 pm: | 
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Can someone provide me with a reference that would indicate the output voltage of a high tension buzz coil (Ford, Detroit, Jefferson, Mesco, etc.) and the output voltage of the low tension coil from the Edison type? |
Paul Gray
Senior Member
Username: paulgray
Post Number: 72
Registered: 05-2003
| | Posted on Wednesday, February 10, 2010 - 07:03 pm: |
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On the high tension coils, you can figure a turn ratio of 50:1. So for a 12 volt input, you'd get 6000 volts out. The low tension ones I believe it depends on the current and number of turns but I have seen 5-600 volts batted about at peak output. Sparks + Flames book may have some specifics in it. Your mileage will vary considerably with the type of coil and input voltage.... |
Richard A. Day Jr.
Senior Member
Username: richardday
Post Number: 846
Registered: 11-2003
| | Posted on Wednesday, February 10, 2010 - 07:42 pm: |
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One of the less understood aspects of the Model T Ford coil was the fact every owner quickly learned Henry put a battery in to start but a magneto to run. This gave little point migration and saved a lot of wear on the points as the magneto put out about 16 volt AC and the points hardly moved as the low tension side of the coil was tranformer coupled to the high voltage side to put it in layman's terms. |
Searcher
Senior Member
Username: searcher
Post Number: 416
Registered: 10-2004
| | Posted on Wednesday, February 10, 2010 - 08:36 pm: |
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Paul, thanks for the information on voltage. |
miro forest
Senior Member
Username: miro
Post Number: 428
Registered: 11-2001
| | Posted on Thursday, February 11, 2010 - 10:11 am: |
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The voltages vary quite a bit.
Recently I measured 3 different coils.
1) JB's coil using a relay as a trembler
2) the coil I described using a slightly different design for the trembler - The trembler is the mechanism to interrupt the current on the low voltage side of the circuit
3) a traditional Model T type coil where the trembler points is activated by the iron core of the primary coil winding
The results:
1) JB's coil was beyond the scale - so it was over 25,000 volts. The primary DC current was just over 2.1 Amps at 12 V - total power input just over 20 Watts
2) my coil design was about 18,000 volts. The primary DC current was 1.1 Amps at 12 V or slightly less than 15 Watts input power.
3) the traditional coil was about 12,000 volts. The current draw was 0.9 Amps or about 10 Watts input power.
On these old engines, especially when getting them started cold, I have found you need every ounce of oomph at the spark plug to get 'er to fire.
Once the engine is warmed up, it isn't so needed.
On the Model T car, the engine had an in-built alternator on the flywheel which put out about 14-16 volts at 300 to 400 Hz. The alternating current helped prevent the erosion of the points.
For boat engines the simple trick is to reverse the battery connections from time to time.
The remaining question is how long will the charge on the battery last?
Clearly, the more you draw the less time you have to run the engine. At shows, that's not a big problem, but when you're out in a boat, you really want to have enough oomph to get back home.
More on these measurements later.
Miro
ps I think I've figured out why JB's coil is so powerful |
B Millar
New member
Username: bcm
Post Number: 3
Registered: 11-2009
| | Posted on Thursday, February 11, 2010 - 11:20 am: |
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Historical Information about Ford/KW ignition coils in 3 parts.
Part 1 The Ford/KW Ignition Company Story
http://www.funprojects.com/pdf/The%20Model%20T%20Ignition%20Coil%20-%20Part%201. pdf
Part 2 The Ford Motor and K-W Ignition Companies
http://www.funprojects.com/pdf/The%20Model%20T%20Ignition%20Coil%20-%20Part%202. pdf
Part 3 Chronology of the Ford/KW Coil Unit
http://www.funprojects.com/pdf/The%20Model%20T%20Ignition%20Coil%20-%20Part%203. pdf |
Ernie
Senior Member
Username: ernie
Post Number: 1162
Registered: 01-2002
| | Posted on Thursday, February 11, 2010 - 11:42 am: |
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I am using a 12 volt 18 amp hour sealed emergency light battery. I charge it every spring and that lasts the whole season |
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