Open Collector Outputs
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Open Collector Outputs

Open Collector Outputs are increasingly common in digital chip design, operational amplifiers and micro-controller (Arduino) type applications, for either interfacing with other circuits or for driving high-current loads such as indicator lamps and relays which maybe incompatible with the electrical characteristics of the control circuit. But what does “open-collector” mean, and…

MOSFET as a Switch
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MOSFET as a Switch

We saw previously, that the N-channel, Enhancement-mode MOSFET (e-MOSFET) operates using a positive input voltage and has an extremely high input resistance (almost infinite) making it possible to interface with nearly any logic gate or driver capable of producing a positive output. We also saw that due to this very…

The MOSFET
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The MOSFET

As well as the Junction Field Effect Transistor (JFET), there is another type of Field Effect Transistor available whose Gate input is electrically insulated from the main current carrying channel and is therefore called an Insulated Gate Field Effect Transistor. The most common type of insulated gate FET which is used…

Bipolar Transistor
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Bipolar Transistor

In the diode tutorials we saw that simple diodes are made up from two pieces of semiconductor material to form a simple pn-junction and we also learnt about their properties and characteristics. If we now join together two individual signal diodes back-to-back, this will give us two PN-junctions connected together…

PNP Transistor
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PNP Transistor

Basically, in this type of transistor construction the two diodes are reversed with respect to the NPN type giving a Positive-Negative-Positive type of configuration, with the arrow which also defines the Emitter terminal this time pointing inwards in the transistor symbol. Also, all the polarities for a PNP transistor are reversed which means…

NPN Transistor
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NPN Transistor

In the previous tutorial we saw that the standard Bipolar Transistor or BJT, comes in two basic forms. An NPN (Negative-Positive-Negative) type and a PNP (<b”>Positive-Negative-Positive) type.</b”> The most commonly used transistor configuration is the NPN Transistor. We also learnt that the junctions of the bipolar transistor can be biased in one of three different ways – Common…