If the gate-channel junction of a JFET was not reverse biased the JFET would just act as a forward biased diode across that junction and the gate would cease to have any control over the channel conductance. For the same reason in a MOSFET the substrate-source/channel/drain junction must remain reverse biased. The MOSFET could not act as a MOSFET.
no we not use resistance in place of diode.
Backward diode
you want to keep the channel electrically isolated from the gate (jfet) or substrate (mosfet) so that it operates as a fet, don't you? if it was forward biased it would just be a diode with no field effect.
It depends. If you only want to turn the motor in one direction, then you could simply use a medium power mosfet (eg:IRF530) connected to an output pin on the PICAXE, and with a backward diode around the motor. If you need to change direction, it's best to use an L293D, which allows independent bidirectional control of two motors.
the current in mosfet is controlled by electric field where as in poto diode is controlled by intensity of light
tel me the devices like diode,mosfet,bjt....etc.
If the gate-channel junction of a JFET was not reverse biased the JFET would just act as a forward biased diode across that junction and the gate would cease to have any control over the channel conductance. For the same reason in a MOSFET the substrate-source/channel/drain junction must remain reverse biased. The MOSFET could not act as a MOSFET.
AC chopper is also called AC voltage controller. In AC voltage controller, we use 2 thyristors as switching element. In AC chopper we use MOSFET or IGBT as switching element with diodes in bridge rectifier for bidirectional flow of current. This use of mosfet switch has the following advantages over thyristor: * no separate firing circuit are needed for Mosfet ( it can be driven directly by interfacing it with MC) whereas firing circuits are needed for SCR. *when the line current drops to zero SCR turns off due to natural commutation( when it reaches 172 deg) ; mosfet- user control - we can turn on and off as per our requirement. * snubber circuit is needed for thyristor phase control method. By using mosfet in diode rectifier provides internal snubber
Use a mosfet driver instead of a simple resistor. Using a resistor to control the mosfet is a bad idea anyways because you will have terrible control (mosfets are voltage controlled. Take a look at the response curve for your mosfet). If your mosfet is fully on, its ratings may be too low for continuous operation or the power dissipation is too low for the transition between off an on an that is killing your mosfet.
what is a mosfet amplifier
The use of the pn diode is for rectification. It can also be used as a switch.
no we not use resistance in place of diode.
Backward diode
MOSFET is an acronym standing for Metal Oxide Semiconductor Field Effect Transistor.
Diode is a two terminal semicon. Diode is a Switching device
not yet