Silicone compounds are used in thousands of electronic systems to seal, bond, coat, and encapsulate components, enabling them to perform reliably under challenging conditions. Formulators continue to improve silicones to make them easier to use and to offer a wider variety of properties.
In the Diode articles we saw that simple diodes are made up from two pieces of semiconductor material, either silicon or germanium 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 in series that share a common P or N terminal.
Bypass Diodes which in electronics we know as free-wheeling diodes, are wired in parallel with individual solar cells or panels, to provide a current path around them in the event that a cell or panel becomes faulty or open-circuited. This allows a series (called a string) of connected cells or panels to continue supplying power at a reduced voltage rather than no power at all.
Spencer Kent stands nervously in front of Team D.R.A.D.I.S.' booth at Rice University's annual Engineering Design Showcase. Judging begins in about 10 minutes, and his teammate Galen Schmidt is frantically typing computer code into a laptop beside the team's custom-made radar system.
When used as an AC signal amplifier, the transistors Base biasing voltage is applied in such a way that it always operates within its “active” region, that is the linear part of the output characteristics curves are used. However, both the NPN & PNP type bipolar transistors can be made to operate as “ON/OFF” type solid state switches by biasing the transistors base differently to that of a signal amplifier.
Light Emitting Diodes or LED´s, are among the most widely used of all the different types of semiconductor diodes available today. They are the most visible type of diode, that emit a fairly narrow bandwidth of either visible light at different coloured wavelengths, invisible infra-red light for remote controls or laser type light when a forward current is passed through them.
Now that we know what is an LED, we need some way of controlling it by switching it “ON” and “OFF”. The output stages of both TTL and CMOS logic gates can both source and sink useful amounts of current therefore can be used to drive an LED. Normal integrated circuits (ICs) have an output drive current of up to 50mA in the sink mode configuration, but have an internally limited output current of about 30mA in the source mode configuration.