How to calculate base resistance of a transistor?
Therefore, with simple transposition of the above formula, the following formula provides the base resistance: Rb = (Vi – Vbe) / Ib. To guarantee that the transistor operates in the saturation region, we multiply the base current by a factor of three.
What’s the maximum collector rating of a transistor?
Usually, a general-purpose transistor such as the PN2222 has maximum collector rating (Ic) of 600-mA DC. If your load requires more current, then it is common sense to consider transistors with a larger Ic rating.
What happens when you use a transistor as a switch?
Transistors that are fully “ON” are said to be in their Saturation region. Transistors that are fully “OFF” are said to be in their Cut-off region. When using the transistor as a switch, a small Base current controls a much larger Collector load current.
What kind of resistor do I need for a switching calculator?
For switching applications, a ¼-watt resistor with 5-% tolerance usually works fine. In order to use this calculator, you will need to know the input switching voltage (Vi), supply voltage Vcc, and the load current iL. Use the Standard Resistor Values chart to find the nearest standard resistor value.
How is the base of a transistor connected to the ground?
Because when the open collector is ‘high’ then the base of the transistor is at 12 V and it appears the 1 kohm resistor didn’t affect anything, and then when the open collector goes ‘low’ then the base is connected to ground through the output of the SN7407. So basically, what would the difference be if there was no 1 kilo-ohm resistor at all?
What should the base resistor be for a bipolar transistor?
For hard saturation, engineers usually choose a value of 10. Remember that a bipolar transistor is a current amplifier, because a small amount of current “Ib” through the base controls a larger amount of current “Ic” flowing through its collector.