Hi everyone,
I was thinking through a problem involving a chain of diodes. I assumed a model of the diode that, below 0.7V, the diode does not conduct, and above this voltage, it behaves as a resistor (with a 0.7V voltage drop).
Now, the circuit in question is a 9V DC source with a load resistor and 3 diodes in a row. I postulated that there would be values of the load resistor which would result in a non-conducting circuit, as the value of the load resistor effects the voltage drop over the diodes.... if the load resistor is of such a large value, then *if* the circuit was conducting, the voltage drop over the resistor would be so large that the resulting voltage drop over the chain of diodes would mean that the diodes would not have enough bias. Is this correct?
+9v ----- load resistor ------- ||> ---- ||>----||>----- ground
I tried to check this in spice, but found that the voltage drop over the diodes only decreases with increased values of the load resistor... I assume this is because spice is using a more accurate model than in my hypothetical example.
Thanks
Taras
I was thinking through a problem involving a chain of diodes. I assumed a model of the diode that, below 0.7V, the diode does not conduct, and above this voltage, it behaves as a resistor (with a 0.7V voltage drop).
Now, the circuit in question is a 9V DC source with a load resistor and 3 diodes in a row. I postulated that there would be values of the load resistor which would result in a non-conducting circuit, as the value of the load resistor effects the voltage drop over the diodes.... if the load resistor is of such a large value, then *if* the circuit was conducting, the voltage drop over the resistor would be so large that the resulting voltage drop over the chain of diodes would mean that the diodes would not have enough bias. Is this correct?
+9v ----- load resistor ------- ||> ---- ||>----||>----- ground
I tried to check this in spice, but found that the voltage drop over the diodes only decreases with increased values of the load resistor... I assume this is because spice is using a more accurate model than in my hypothetical example.
Thanks
Taras