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#21
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Randolph > wrote in :
> > "TeGGeR®" wrote: >> >> Got a URL or a pic? I'd like to add that diode. >> >> The pics I found showed resistors, but no diodes. > > I have looked long and hard at the photos of the ignitor. The darlington > device is definitely from STM (http:/www.stm.com). The part number is > hard to decipher, but I am quite certain the first line of the part > number is BUxy41. I can't for the life of me see if "x" is actually a > character or just picture noise. The "y" looks like an "8" or a "9". The > second line of the part number almost certainly is "ZT". This is > consistent with "BU941ZT", which is an actual STM part number with a > package type like the one in the ignitor photo. The description is "HIGH > VOLTAGE IGNITION COIL DRIVER NPN POWER TRANSISTOR". See > http://www.st.com/stonline/books/ascii/docs/5288.htm for details. The > data sheet is at http://www.st.com/stonline/books/pdf/docs/5288.pdf. The > data sheet shows the diode between emitter and collector. The diode is INTERNAL to the transistor package. Probably on the same substrate as the xstr. > > The IC in the photo looks like it has part number U2226B, and a good > guess is that the TFK in the first line stand for Telefunken, a German > semiconductor manufacturer later renamed TEMIC and eventually bought by > Vishay. I have not found any data sheet for the U2226B, but I believe it > is an opto-coupler. > 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) -- Jim Yanik jyanik at kua.net |
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#22
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Randolph > wrote in :
> The > data sheet shows the diode between emitter and collector. 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/educat...n/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/ignit...ion/index.html -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
#24
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"TeGGeR®" > wrote in
: > Randolph > wrote in > : > >> The >> data sheet shows the diode between emitter and collector. > > > 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/educat...tion/thegame.h > tml > > 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/ignit...ion/index.html > > > 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. -- Jim Yanik jyanik at kua.net |
#25
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Jim Yanik .> wrote in
: > "TeGGeR®" > wrote in > : > >> Randolph > wrote in >> : >> >>> The >>> data sheet shows the diode between emitter and collector. >> >> >> 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/educat...nction/thegame. >> h tml >> >> 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/ignit...ion/index.html >> >> >> > > 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/ignit...ion/index.html http://www.tegger.com/hondafaq/ignit...adigniter.html On these two pages, is the current flow through the transistors correctly depicted? Nobody has answered that question yet. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
#26
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"TeGGeR®" > wrote in
: > Jim Yanik .> wrote in > : > >> "TeGGeR®" > wrote in >> : >> >>> Randolph > wrote in >>> : >>> >>>> The >>>> data sheet shows the diode between emitter and collector. >>> >>> >>> 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/educat...nction/thegame >>> . h tml >>> >>> 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/ignit...ion/index.html >>> >>> >>> >> >> 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/ignit...ion/index.html > http://www.tegger.com/hondafaq/ignit...adigniter.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. -- Jim Yanik jyanik at kua.net |
#27
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Jim Yanik .> wrote in
: >> > > 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/educat...n/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/educat.../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/educat.../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... -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
#28
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"TeGGeR®" > wrote in
: > 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. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
#29
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"TeGGeR®" > wrote in message
... > Jim Yanik .> wrote in > : > 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/educat...n/forward.html > 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 |
#30
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In article >,
"TeGGeR®" > wrote: > Jim Yanik .> wrote in > : > > > "TeGGeR®" > wrote in > > : > > > >> Randolph > wrote in > >> : > >> > >>> The > >>> data sheet shows the diode between emitter and collector. > >> > >> > >> 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/educat...nction/thegame. > >> h tml > >> > >> 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/ignit...ion/index.html > >> > >> > >> > > > > 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. Most materials have an electron flow, which goes from negative to positive. I've heard that some materials can have a proton flow. Both may exist in a vacuum. Current flow arrows on diagrams go from positive to negative. Bipolar transistors are current amplifiers. When a current flows through the base-emitter diode junction, a stronger current is allowed to flow from the collector to the emitter. The C-E junction is .2 to .4 volts when the B-E junction is saturated (~.65 V). The current gain for a power transistor is usually 10 to 100. Darlington pairs have that gain squared. Gains are not at all consistent so they're usually specified as a range. MOSFETs are tiny voltage controlled amplifiers. Absolutely zero static current is required to turn them on or off; just the capacitance current. Because of their infinite current gain, millions may be paralleled on a single chip to satisfy any current load. Their voltage gain is very low - a typical gate threshold voltage is 4V and a typical gate saturation voltage is 10V. There's no voltage drop between the source and drain, only resistance. High voltage capability makes each MOSFET junction larger and dramatically increases resistance. IGBTs are similar to bipolar transistors but with an insulated gate like a MOSFET. They have the high voltage capacity of bipolars but need no driving current like a MOSFET. They're very slow so they're usually limited to controlling industrial motors. (Honda hybrid cars use them for their motors.) > http://www.tegger.com/hondafaq/ignit...ion/index.html > http://www.tegger.com/hondafaq/ignit...adigniter.html > On these two pages, is the current flow through the transistors correctly > depicted? Nobody has answered that question yet. |
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