Ignition updates to the Unofficial FAQ

awesome! that one without capacitor is /real/ ugly...

 

It reminds me of my Mazda rotary with points. I could see the dwell begin
to take up too much time as the RPM got higher.

 

It reminds me of my Mazda rotary with points. I could see the dwell begin
to take up too much time as the RPM got higher.

 

The diode is INTERNAL to the transistor package.
Probably on the same substrate as the xstr.

I found ICs that were specifically designed for ignition control and
driving the Darlingtons,but none with the same pin count of the IC
pictured,nor any similarity to its part number.
I do not believe it's an optocoupler,but a full control IC.Probably with
circuitry to square up(shape) the drive pulse,and provide enough drive
current,and IIRC,the ICs monitored and regulated coil current.(that would
enable faster switching)

 

The diode is INTERNAL to the transistor package.
Probably on the same substrate as the xstr.

I found ICs that were specifically designed for ignition control and
driving the Darlingtons,but none with the same pin count of the IC
pictured,nor any similarity to its part number.
I do not believe it's an optocoupler,but a full control IC.Probably with
circuitry to square up(shape) the drive pulse,and provide enough drive
current,and IIRC,the ICs monitored and regulated coil current.(that would
enable faster switching)

 

So then it wouldn't make much sense to try and show it.

Randolph, I'm having trouble understanding the current path through the
transistor. I found this page:
http://nobelprize.org/physics/educational/transistor/function/thegame.html

It helps me understand more, but I don't get which way the current goes
through the base electrode. I have a suspicion that my diagrams show the
current going the wrong way through the transistor.
http://www.tegger.com/hondafaq/igniter-operation/index.html

 

So then it wouldn't make much sense to try and show it.

Randolph, I'm having trouble understanding the current path through the
transistor. I found this page:
http://nobelprize.org/physics/educational/transistor/function/thegame.html

It helps me understand more, but I don't get which way the current goes
through the base electrode. I have a suspicion that my diagrams show the
current going the wrong way through the transistor.
http://www.tegger.com/hondafaq/igniter-operation/index.html

 

I had a '74 RX-4 Coupe!

You guys...I swear...

If the subject gets any more high-flown, it's gonna head for outer space.

This is excellent info. Now I've got to make another page: More detail for
the Electronics Whiz.

 

I had a '74 RX-4 Coupe!

You guys...I swear...

If the subject gets any more high-flown, it's gonna head for outer space.

This is excellent info. Now I've got to make another page: More detail for
the Electronics Whiz.

 

There's two current paths;the B-E path and the C-E path(main path).
Current flows the opposite direction of the emitter arrow,for both base and
collector currents.

 

There's two current paths;the B-E path and the C-E path(main path).
Current flows the opposite direction of the emitter arrow,for both base and
collector currents.

 

I'm having trouble getting my mind around this.

I am aware that "flow" is _commonly_ considered to be from the positive to
negative terminals of the battery, but the electrons themselves go in the
OTHER direction.

http://www.tegger.com/hondafaq/igniter-operation/index.html
http://www.tegger.com/hondafaq/igniter-operation/badigniter.html
On these two pages, is the current flow through the transistors correctly
depicted? Nobody has answered that question yet.

 

I'm having trouble getting my mind around this.

I am aware that "flow" is _commonly_ considered to be from the positive to
negative terminals of the battery, but the electrons themselves go in the
OTHER direction.

http://www.tegger.com/hondafaq/igniter-operation/index.html
http://www.tegger.com/hondafaq/igniter-operation/badigniter.html
On these two pages, is the current flow through the transistors correctly
depicted? Nobody has answered that question yet.

 

The electrons are what's doing the moving,and they flow from neg to pos.

 

The electrons are what's doing the moving,and they flow from neg to pos.

 

The electrons flow from POSITIVE TO NEGATIVE. The electrons go from where
they are (-) to where they're not: The "holes" (+).
http://nobelprize.org/physics/educational/transistor/function/forward.html

It's the actual everyday signal that's commonly perceived to go from
negative to positive.

But we have THREE paths in a transistor ("transfer resistor"). For a non-
techie, this is non-intuitive. I do not get how TWO terminals can have
THREE paths.

Please try to understand that I am not trying to be difficult, but that
this is not at all making sense to me.

I am hoping that someone, somewhere, will post with an explanation that
makes sense to my mind. In my professional life I have taught and trained
many, many individuals, and most have had certain things that just would
not "click" until the information was presented a certain way. I am seeking
that way, and I will persist until I find it. This is driving me crazy.

This graphic:
http://nobelprize.org/physics/educational/transistor/function/amplification
..html
(all on one line; copy-and-paste as necessary)
shows the signal path from base electrode to collector.

This one:
http://nobelprize.org/physics/educational/transistor/function/pointsymbol.h
tml
(again, all on one line)
appears to show the path from emitter to collector.

I do not get this and I am trying madly to understand. Graham W would be
able to correct me in an instant. He has been the most persnicketly
critical observer and the most productive from my point of view. Graham,
where aaaaaare you?...

Graham was the ONLY one to suggest alterations to the Main Relay function
graphics. Graham was the ONLY one to inform me of certain HTML errors, the
correction of which make it easier for browsers to display the intended
information.

Ah, but wait. I just thought of something: alt.electronics. Back soon...

 

The electrons flow from POSITIVE TO NEGATIVE. The electrons go from where
they are (-) to where they're not: The "holes" (+).
http://nobelprize.org/physics/educational/transistor/function/forward.html

It's the actual everyday signal that's commonly perceived to go from
negative to positive.

But we have THREE paths in a transistor ("transfer resistor"). For a non-
techie, this is non-intuitive. I do not get how TWO terminals can have
THREE paths.

Please try to understand that I am not trying to be difficult, but that
this is not at all making sense to me.

I am hoping that someone, somewhere, will post with an explanation that
makes sense to my mind. In my professional life I have taught and trained
many, many individuals, and most have had certain things that just would
not "click" until the information was presented a certain way. I am seeking
that way, and I will persist until I find it. This is driving me crazy.

This graphic:
http://nobelprize.org/physics/educational/transistor/function/amplification
..html
(all on one line; copy-and-paste as necessary)
shows the signal path from base electrode to collector.

This one:
http://nobelprize.org/physics/educational/transistor/function/pointsymbol.h
tml
(again, all on one line)
appears to show the path from emitter to collector.

I do not get this and I am trying madly to understand. Graham W would be
able to correct me in an instant. He has been the most persnicketly
critical observer and the most productive from my point of view. Graham,
where aaaaaare you?...

Graham was the ONLY one to suggest alterations to the Main Relay function
graphics. Graham was the ONLY one to inform me of certain HTML errors, the
correction of which make it easier for browsers to display the intended
information.

Ah, but wait. I just thought of something: alt.electronics. Back soon...

 

Just checked message counts.
sci.electronics.misc
sci.electronics.repair
and
alt.home.repair
seem better choices, in case anyone wants to follow along...

I'm hoping to elicit responses from somebody like Sam Goldwasser.

 

Just checked message counts.
sci.electronics.misc
sci.electronics.repair
and
alt.home.repair
seem better choices, in case anyone wants to follow along...

I'm hoping to elicit responses from somebody like Sam Goldwasser.

 

There is a big part of the confusion - electrons flow from [-] to [+].

The entire "hole" thing never helped me, either. I got a lot farther when I
started thinking of where the "positives" flowed, because both vacuum tubes
(which were still common when I was learning electronics) and NPN
transistors (which are the most common now but least common originally, both
for technical reasons) use negative ground. Trying to follow electron flow
distorts the idea of the ground, while thinking of "positives" flowing from
the power supply to ground worked great. (Also the "positives" flow in the
direction of the arrow on the emitter.)

For NPN transistors, here is the simple view. The emitter is grounded and
the collector has positive voltage applied to it. The transistor doesn't
conduct because the collector-base junction is reverse biased. Now positive
voltage is applied to the base. Below about 0.7 volts on the base nothing
much happens. As 0.7 volts is approached the base-emitter junction starts
drawing current, just like any other ordinary silicon diode. The
base-emitter current causes tens to hundreds of times that much current to
flow from the collector to emitter. As the base voltage rises to about 0.8
or 0.9 volts, the base-emitter current is so high that the collector current
can't go any higher - the voltage at the collector has dropped to only
0.1-0.2 volts, and the entire supply voltage (like the 12V battery) is
across whatever load is between the power supply and the collector. In the
ignition circuit, the collector has grounded the primary of the coil. This
condition is called "saturation" because increasing the base current doesn't
do anything to the collector any more.

It is important in switching circuits like the ignition to saturate the
transistor. If the collector voltage doesn't go very near ground, the
transistor has to dissipate the current times whatever voltage is left. If
the voltage is only twice the saturation voltage (say, 0.3 instead of 0.15)
the transistor has to dissipate twice the power.

Mike