Hey guys! Let's look at the specs for these diodes -
The 1N400x series of diodes is rated at 1 Amp max. current.
The maximum reverse voltage for the 1N4001 is 50 Volts.
1N4002 - 100 V
1N4003 - 200 V
1N4004 - 400 V
1N4005 - 600 V
1N4006 - 800 V
1N4007 - 1000 V
There is no difference now between the 1N4148 and the 1N914 diode. Manufacturers now just make the 1N4148 and when somebody orders some 1N914 diodes, they just change the part number marked on the diode and raise the price. The 1N914 is obsolete. The only difference was the reverse current leakage rating - which won't generally affect hobbiests.
The 1N4148 "generally" can handle 0.2 to 0.3 Amp - depending on who made the diode. Specs are all over the place.
The maximum reverse voltage rating for a 1N4148 "generally" runs from 75 to 100 volts.
The 1N4148 diode is a "signal" diode and can respond up into the MHZ region.
The 1N400x series of diodes is a "power" diode", with higher internal capacitance, and slower response time. But for the average relay, etc. it will be just fine - (and cheap, too.)
If you are using the 1N4148 diodes as a spike snubber across a relay, please be sure it is a SMALL (physical coil size) relay, such as a plug-in molded DIP relay.
If you are using something with a large coil, such as a 12-volt automotive relay, or starter relay - the spike coming back at the diode will likely have sufficient energy to destroy it.
I would suggest for the larger relays, that you use a 1N4004 or better.
Bruce - KK0S