What does B+ in FSM
Thread Starter
Instructor
Joined: Sep 2002
Posts: 156
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From: North Aurora IL
What does B+ in FSM
I am trouble shooting some electrical stuff and see B+. It is listed as "positive terminal" in the acronym portion of the FSM. I assume it means "battery positive", is that correct?
-Dave
-Dave
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Joined: Jun 2008
Posts: 610
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Yeah. I think this nomenclature dates back to the early days of electricity. Nowadays it is often used to denote the main power source in general, not necessarily just a battery. For example it could also be referring to the alternator.
Instructor
Joined: May 2009
Posts: 118
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From: Alexandria Kentucky
Yes. That's what it means.
B+ is a holdover term from back in the days of tube type radios, particularly the portable radios. A+ was for the lower filament voltage - anywhere from 3 to 6 volts usually and B+ was the higher voltage that the tube's plate circuits required - in those days usually 67 volts. There was also a "C" voltage which was for a portion of the circuitry called the Grid circuit. The early tube portable radios had three batteries in them and were the size of a mail box due to the need for the three batteries.
Now that things are solid state and require just one voltage, the designator is Vcc which is anywhere from 3.3 volt (cell phones for instance) up several hundred volts for the MOSFET solid state devices used in the electric cars.
But the automobile service manuals for regular cars still use the B+ designator for the voltage levels -- probably because there are still enough old farts like me around who remember the old designations.
B+ is a holdover term from back in the days of tube type radios, particularly the portable radios. A+ was for the lower filament voltage - anywhere from 3 to 6 volts usually and B+ was the higher voltage that the tube's plate circuits required - in those days usually 67 volts. There was also a "C" voltage which was for a portion of the circuitry called the Grid circuit. The early tube portable radios had three batteries in them and were the size of a mail box due to the need for the three batteries.
Now that things are solid state and require just one voltage, the designator is Vcc which is anywhere from 3.3 volt (cell phones for instance) up several hundred volts for the MOSFET solid state devices used in the electric cars.
But the automobile service manuals for regular cars still use the B+ designator for the voltage levels -- probably because there are still enough old farts like me around who remember the old designations.
