Your friend who works for Photons 'R Us wants help with a circuit to drive the new LED his company has developed. He wants to turn on the LED based on a digital signal which swings between VDD and OV. Unfortunately the LED when it is on drops a voltage VD across of it and requires a current of IL to flow through it to produce light. You ask your 10A Professor for help and he shows you two circuits shown in figure 5, of course in his usual absent-minded self does not tell you how each one works, he only cryptically says one inverts and the other does not.

Question in the photo attached please

Light-emitting diodes (LEDs) are diodes made with III-V compound semiconductor materials such as aluminum gallium arsenide (AlGaAs), aluminum indium gallium phosphide (AllnGaP) or indium gallium nitride (InGaN), instead of silicon. The LEDs emit light when the device is operated under forward bias. LEDs of different colors have different turn-on voltages VD(on). For example: Color VD(on) Red ~ 1.6 V Yellow ~ 1.7 V (a) Model these five LEDs with a simplified piecewise linear model. (b) A rule of thumb is that it takes about 1 mA of current to "light" an LED while~ 10 mA is needed for it to appear bright. Use the piecewise linear model for the LEDs, for the over-voltage indicator circuit to the right, find the values of Vin which will cause D₁ or D₂ to light (i.e. when ID1 or ID2 exceeds 1 mA). Green ~ 1.8 V Blue ~ 2.8 V loks o mu Vin Red LED Red LED White ~ 3.8 V + lov 21 D₁ D2 -10V o t Vout 오

#4(a) An 8.2 V (8.2 V at 25 °C) has a positive temperature coefficient of 5.4 mV/°C. What is the output voltage if the temperature rises to 90° C? Page | 4 b) Name two applications of the Zener Diode