Re: Johnson 150 Fast Strike rev limiting @3000 (video link!)! New boat please help!!
Re: Johnson 150 Fast Strike rev limiting @3000 (video link!)! New boat please help!!
I can't answer your question without paragraphs and paragraphs of electronic technobabble.
I also would need to be able to draw circuits out, and I cannot do that here.
But, no, the diode is not detecting ground, and no, grounding one side of a diode does not "send 12v+- to the diode".
No, the signal voltages do not vary as in your example of 3.3v to 12v. Doesn't work that way.
You will have to know how a diode works, specifically, the "cathode negative with respect tothe anode" aspect of diode operation.
If the lead with the silver band (cathode) is negative with respect to the other lead (anode) the diode will conduct current.
Consider a diode with the anode (no band lead) connected to the positive terminal of a battery. The cathode is connected to the negative terminal.
So, the diode is forward biased, as the "cathode is negative with respect to the anode". Current will flow. If the battery is sufficient, and almost all are (even the AA cells), the diode will burn up. It will fail, either shorting internally, or opening up completely internally. Depends on how much current, the diode rating, and any huge number of factors as to which way it will fail. Most OPEN up.
But reverse the leads. Now the diode is reverse biased, with the cathode on the positive battery terminal, and the anode on the negative battery terminal. It will now pass no current. And it will exist there indefinitely, happily, unless certain specs are exceeded.
The major one is PRV, peak reverse voltage. If the diode is rated 1000v like the one you suggest to use, then a voltage spike of 1,500 volts will fry the diode. But a voltage spike of 900v will not do any damage.
There is much more to it, terms like floating voltage, and virtual ground, but the whole deal centers around the fact that the pack "sees" a ground when the affected sensor triggers. Whatever the floating voltage was on the tan line from the pack, now it is ground because the sensor switched. So the pack does it's thing....SLOW. Or if the "no oil sensor" switches to ground, the horn sounds.
Play around with your electrical system. Put your meter on volts 20v DC range, and measure the voltage on the tan wire from the pack. I have no idea what it will be. The pack electronics will be determining that. It could very well be 12v, floating. Then short the tan wire to ground. Horn will sound, and engine will go into SLOW. It is all in the pack, not the diode. Diode is a dumb component.
If you look at the wiring diagram, you will see that in the case of the blocking diode, the way the other sensors are wired, if one of them goes to ground, (negative with respect to), the diode will not conduct, allowing the tan wire to stay at it's floating level.
It is very hard to explain. I wish I could draw it out. Just remember "cathode negative with respect to anode" turns a diode on.
That's what you do with your meter when you reverse the leads. You swap that "negative with respect to" factor.
One other factor to consider is the voltage drop across the diode. Most all diodes have a 0.7vdc voltage drop across them when forward biased. So, if the cathode was grounded, you will measure .7 volts on the anode, in a properly designed electronic circuit.
In my example above with a diode and battery, you would always have a load in the circuit to limit the current.
That load is provided inside the pack. The pack itself limits the current on the tan line to ground when the sensor switches.
I think you are assigning functionality to the diode when you should consider the pack as the driving electronic device here.
Sorry for the technobabble.
Re: Johnson 150 Fast Strike rev limiting @3000 (video link!)! New boat please help!!
I can't answer your question without paragraphs and paragraphs of electronic technobabble.
I also would need to be able to draw circuits out, and I cannot do that here.
But, no, the diode is not detecting ground, and no, grounding one side of a diode does not "send 12v+- to the diode".
No, the signal voltages do not vary as in your example of 3.3v to 12v. Doesn't work that way.
You will have to know how a diode works, specifically, the "cathode negative with respect tothe anode" aspect of diode operation.
If the lead with the silver band (cathode) is negative with respect to the other lead (anode) the diode will conduct current.
Consider a diode with the anode (no band lead) connected to the positive terminal of a battery. The cathode is connected to the negative terminal.
So, the diode is forward biased, as the "cathode is negative with respect to the anode". Current will flow. If the battery is sufficient, and almost all are (even the AA cells), the diode will burn up. It will fail, either shorting internally, or opening up completely internally. Depends on how much current, the diode rating, and any huge number of factors as to which way it will fail. Most OPEN up.
But reverse the leads. Now the diode is reverse biased, with the cathode on the positive battery terminal, and the anode on the negative battery terminal. It will now pass no current. And it will exist there indefinitely, happily, unless certain specs are exceeded.
The major one is PRV, peak reverse voltage. If the diode is rated 1000v like the one you suggest to use, then a voltage spike of 1,500 volts will fry the diode. But a voltage spike of 900v will not do any damage.
There is much more to it, terms like floating voltage, and virtual ground, but the whole deal centers around the fact that the pack "sees" a ground when the affected sensor triggers. Whatever the floating voltage was on the tan line from the pack, now it is ground because the sensor switched. So the pack does it's thing....SLOW. Or if the "no oil sensor" switches to ground, the horn sounds.
Play around with your electrical system. Put your meter on volts 20v DC range, and measure the voltage on the tan wire from the pack. I have no idea what it will be. The pack electronics will be determining that. It could very well be 12v, floating. Then short the tan wire to ground. Horn will sound, and engine will go into SLOW. It is all in the pack, not the diode. Diode is a dumb component.
If you look at the wiring diagram, you will see that in the case of the blocking diode, the way the other sensors are wired, if one of them goes to ground, (negative with respect to), the diode will not conduct, allowing the tan wire to stay at it's floating level.
It is very hard to explain. I wish I could draw it out. Just remember "cathode negative with respect to anode" turns a diode on.
That's what you do with your meter when you reverse the leads. You swap that "negative with respect to" factor.
One other factor to consider is the voltage drop across the diode. Most all diodes have a 0.7vdc voltage drop across them when forward biased. So, if the cathode was grounded, you will measure .7 volts on the anode, in a properly designed electronic circuit.
In my example above with a diode and battery, you would always have a load in the circuit to limit the current.
That load is provided inside the pack. The pack itself limits the current on the tan line to ground when the sensor switches.
I think you are assigning functionality to the diode when you should consider the pack as the driving electronic device here.
Sorry for the technobabble.
