We know that the voltage drop across a rectifier diode like 1N4001 is 0.7V in forward bias. What about the voltage drop across a 1N4148? Is a 1N4148 diode in silicon family or it is a germanium diode?
The last question is what If I need to use a high speed diode like 1n4148 but with a current capability of 400mA and a MAX voltage of say 200V? Any diode? Actually I have a switching power supply which originally uses a 1N4148, Now I want to replace the said 1N4148 with a more powerful similar diode, Any suggestion please?
The 1N4148 is silicon, so .7V. For a high speed diode in a switcher, I would use a Schottky. For instance, a CSD01060A diode has ZERO recovery time, and way higher voltage and current ratings than you need.
He is talking switching power supply. The MUR120 is a good diode for that. 45nS.
A 1N4002 is rated at 60hz. Typically does not have a Trr rating because it is so slow. Should never be used in a switcher.
Also try uF4002. Also ten times slower but a good power supply diode.