The Electronics Universe

This is a work in progress, and as such is subject to change, so i will be editing this post as i think of more detail and better ways of presenting it, but if i'm gonna do this then i've got to start somewhere, so for now here goes,

How it Works:

as illustrated in the figure below of an NPN transistor, if we apply a small amount of base current it will cause a much larger amount of collector current to flow, this is how a transistor is able to amplify a signal, and the ratio of base to collector current is called the current gain, symbolized by the greek letter beta "β", the current gain is also sometimes called "Hfe",

in the example below, lets assume that we have a base current of 1 milliamp, and a collector current of 100 milliamps, the ratio would be 100:1 so the current gain of this transistor would be 100, so in this case β = 100, here's the formula:

β = I_c / I_b

where:
β = current gain
I_c = collector current
I_b = base current

ok now lets apply 2 milliamps base current, with a current gain of 100 that would yield a collector current of 200 milliamps,

so now it can be seen how it is able to amplify a signal, because that a small amount of base current causes a much larger amount of collector current to flow, just a 1 milliamp increase in base current caused a 100 milliamp increase in collector current,



β = I_c/I_b

V_cc = Collector Supply Voltage
V_bb = Base Bias Supply Voltage
I_b = Base Current
I_c = Collector Current
I_e = Emitter Current
V_be = Base Emitter Voltage, or Voltage measured across the Base and Emitter
V_ce = Collector Emitter Voltage, or Voltage measured across the Collector and Emitter
V_cb = Collector Base Voltage, or Voltage measured across the Collector and Base
R_b = Base Bias Resistor, used to limit the base current
R_L = Load Resistor, used to limit the collector current
β = Current Gain, or HFE

The Exclusive NOR Gate,

The Exclusive NOR Gate is simply an Exclusive OR Gate with its output inverted, so its output goes low when either of its its inputs are high, but not both,

The NOR Gate,

The NOR Gate is simply an OR Gate with its output inverted, so its output goes low when either or both its inputs are high,

The NAND Gate,

the NAND Gate is simply an AND Gate with its output inverted, so its output goes low when both its inputs are high,

The NOT Gate,

also called an Inverter, or Inverting Buffer,

The NOT Gate does exactly the same thing as the Buffer except its output is inverted,

This thread is for discussing the topics raised in the: Digital 101, digital numbering systems, thread, i am keeping that thread locked to keep it neat and orderly,

BCD, or Binary Coded Decimal:

in BCD, 4 binary digits or bits represent a single decimal digit, and 4 more binary digits or bits are required for the next decimal digit, and 4 more for the next and so on, it is almost like hexadecimal except the binary values higher than 9 representing A through F for any given digit are either ignored, or considered illegal or garbage, or skipped entirely, because in decimal a single digit does not go any higher than 9, here is a short example of 2 digit BCD counting from 00 to 20,

0000,0001 = 01
0000,0010 = 02
0000,0011 = 03
0000,0100 = 04
0000,0101 = 05
0000,0110 = 06
0000,0111 = 07
0000,1000 = 08
0000,1001 = 09
0001,0000 = 10
0001,0001 = 11
0001,0010 = 12
0001,0011 = 13
0001,0100 = 14
0001,0101 = 15
0001,0110 = 16
0001,0111 = 17
0001,1000 = 18
0001,1001 = 19
0010,0000 = 20


now to give some contrast here, the channel selector in a cobra 29 LTD Classic uses 1 and 1/2 digit BCD for its channel code going into the PLL chip, whereas in a typical EPT 3600-xxx chassis like the galaxy 33, and practically every other radio using an MC145106 PLL chip, its channel selector uses 8 bit binary for its channel code, and the two are not interchangeable, BCD and Binary are two very different numbering systems,

Binary:

in Binary, each digit has only two possible values, 0 and 1, the first digit goes from 0 to 1, before the next digit advances, Binary can have any number of digits although it is usually limited to 8, and these digits are often called bits, this is called base 2, or binary, here is an example using 4 digits, or 4 bit binary,

0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111

At this point I think it prudent to mention that, a 1 is usually equal in voltage to the power supply voltage supplied to the system, and a 0 is equal to ground potential or 0v, in most CB Radios the PLL system is powered by +8Vdc, therefore in such a system, a 1 = 8v, and a 0 = 0v,

up next: Hexadecimal,