nitro joe

My Feedback: (2)

I see the "Ignition loads current verses input voltage"has been locked down seemingly at the request of the author.

Personally,I would have voted that as thread of the month.
Mr.Norton was obviously,and understandably frustrated with the way his thread had veered off it's intended simple course.Many thanks to him,and his efforts.

However... a "new thread" as was suggested by Ladyflyer in her post#109 would be sweet.There seems to be a population of electronic minded modeler's in here.

Partial quote:
"With battery/coil ignition circuits there are many elements outside the simple DC resistance of the coil that will affect the actual operating load. Those factors, like the Ohm's law debate are probably beyond the scope of this topic. Perhaps we could start a new thread ?"

"Current Draw in Pulsed Coils At The Point of Magnetic Saturation" Anyone ?
We could discuss how voltage engine speed ,crankshaft dwell angle etc affect the saturation point as well."


I only wish that I could personally make a meaningful contribution.
I am fascinated,and eating this stuff up with a spoon.

w8ye

My Feedback: (16)

Fifty pages of this thread may get you started?

http://www.rcuniverse.com/forum/m_4344316/tm.htm

bcchi

Go ahead and start a new thread about ignitions. I will muddy up the water and then jump out.
BCCHIAMA 2500

Tired Old Man

My Feedback: (1)

I can make it muddier still with altered timing curves, benefits and drawbacks.

bcchi

You start with a battery and you end up with a big spark. What could be simpler

Tired Old Man

My Feedback: (1)

Eliminating the battery by using a mag?

JNorton

My Feedback: (2)

I know lets use points and a coil hooked in series to a battery. No more arguring about the affects of solid state mutlivibrators or state of the art switching ignition systems. You'll never see a hall effect sensor or an output SCR fail. No worry about dwell either its built into the cam that drives the points.
John
EDIT-> Forgot the smiley.

av8tor1977

My Feedback: (6)

Well, in the spirit of the name of this thread....

I know the Hall Effect sensor is really just a magnetic switch, but how exactly does it work?

Three wires:

Red = + 4.8 volts?
Black = ground?
White = what? Continuity to the red wire when activated??

(To clarify, I am asking about the CH Ignitions, RC EXL, and Ralph Cunningham systems.)

AV8TOR

tkg

My Feedback: (1)

Well not that simple, a typical Hall chip has about 15 electronic parts in it. IT IS NOT a magnet reed switch.
Google Hall Effect and go to the Honeywell site for an excess of details

gkamysz

My Feedback: (19)

You can't count on the wire colors matching the logical value. The typical ignition hall sensors are shorted to ground when a south magnetic field is facing the marked side of the sensor. Of course other systems use different arrangements.

Ladyflyer

My Feedback: (2)

Ed Vollmer

My Feedback: (14)

Matchlocks were the bees knees too - until Flintlocks came along.

Truckracer

My Feedback: (19)

Simple explanation ..... think of a hall effect sensor as simply a magnet controlled transistor. In the presence of the correct polarity magnetic field, the transistor goes into saturation acting as an electronic switch.

w8ye

My Feedback: (16)

And like one guy said - The signal wire is taken to ground

The spark occurs when the signal wire is released from ground

av8tor1977

My Feedback: (6)

Thanks.

That was interesting reading; the Hall Effect .pdf from Honeywell. That is a good analogy, it is quite like a "magnet controlled transistor".

So, if I am understanding correctly, in these ignition systems two of the wires are "hot" and the third wire is grounded when the Hall Effect sensor is actuated, completing a circuit for the control box. (I imagine the circuit charging the CDI capacitor.) Is that correct? (Don't have a loose ignition system here to "play with" right now, but I would like to understand the circuit.)

Any chance of a simple schematic of just the Hall Sensor and it's three wires with their relation to the CDI box?

AV8TOR

w8ye

My Feedback: (16)

On one of mine -

The red wire is + voltage
The black wire is GRND
The white wire is the signal wire. As the magnet passes under the sensor, the white wire is taken to the ground potential of the black wire, and as the magent passes the white wire goes back above ground potential.

av8tor1977

My Feedback: (6)

Ok, thanks W8YE, now that makes sense.

Thanks again,
AV8TOR

gkamysz

My Feedback: (19)

Two wires provide power to run the electronics in the sensor. When conditions are met the sensor output is grounded, and when the conditions cease the signal line is released. What the ignition does with that signal is not related at all, and depends on the design of the ignition unit. The circuit probably begins charging the cap as soon as possible after firing in order to handle as much RPM as possible. The signal line should actually be held high (+5V) and the sensor is sinks current when on to drop the line to (~0V, logic).