Well only ones I have on had are as stated:
only diodes I have enough of (8) are the following:
-- IN194 . IN4148 (switching diode)
-- IN4004 (rectifier diode)
So I'll have to make the trip anyways. So I'll focus on the 1N4001 series as my goal. 
Thanks everyone!
That is as good as a 1N4001 for this application, if you have one then you should use it.
Actually I only have 7.. (I need minimum of 8.. and I usually get a few extras).
3 are silicon types... 4 are 'glass' type? (make any difference? except to my OCD for not being uniform? lol)
I do have 2 x 1N4001's as well though (in hand).. so I guess technically.. with all the above it can work out. Any difference (except voltage max) in using a 4004 vs 4001?
I do have a 10 pack of 1N914 . 1N4148 (switching diodes).. I know you said that is just how they are implemented, but it does stated it on the bag, where the other do not. (FYI)
Is there a preference between silicon vs glass if you have a choice? (why the different bodies anyways?)
Not in this application.
Normally these are lower current, I tend to use these for just switch matrices.
It looks like they're jellybean components, especially on-line. Grab a hundred pack & you can probably forget about buying any more for quite a while.
1N4004 will work.
I am surprised that 1N4001 or 1N4002 are actually manufactured any more! Would they not represent a semi-reject product of a production line which should have improved over time? 
Possibly they actually mark them as lower spec just to suit a market. 
They could be designed with lower breakdown so they can charge a premium for the higher rated part.
That was my point. That would be a totally absurd way to run a business. 
The 1N4001's have been secured (25pk)
Along with the only other diode that have in stock/on the shelf.. (400v, 3A / 1N5404).. just for the archives.
Anywho.. I want to ask about -how- these can be wired for my current project.
I know the above example image is very direct/clear:
but my project is a bit more involved obviously..since it has 8 of them and a relay board..etc.
Current layout:
because my solenoids are currently mounted, and the wiring hidden/routed behind panels..etc..
I just want to be clear how far I need to dig down to do this correctly.
Q1.) Can I just solder wires to each end of the diodes, and connect one side to the GND terminal block, and the other end to each relay terminal where the solenoid wire connects as well?
** Not sure that this even matters.. but there will never be more than on relay/solenoid on at one time. (so would never exceed the 500mA pull anywhere.
** because the solenoids do not care which wires (it stated) were connected to GND or +V.. I just labeled the 'pairs' as1, 2, 3, 4, and routed the wires through the projects physical area(s)..
so if they can not be set up as questioned above.. I will have to pull all them out and again to make sure I know which wire is going to the GND terminal and which wire is going to the relay board in order ensure I connect the diode in the proper alignment.
Thanks
Yes.
Thanks.
I'm going to plug in one end of the diode into each screw terminal (not the common [middle] screw, the screw that is connected to the solenoid wire)
and each other end of the diode will connect to the common GND terminal block all solenoids are connected to.
Shouldnt take more than 15 minutes wish me luck! lol
It is a common misconception that it is desirable to mount the diode close to the solenoid itself.
This turns out to be quite wrong - the diodes should actually be mounted at the relay and power supply connections.
PERFECT!
I have them mounted @ the relay screw terminals.... and the other ends connected to the GND terminal block that all the other solenoid wires connect to. The solenoids themselves are not close..and the wire is even further.
Anyways.. I wired them in as described above, and it works great!.. I am no longer getting any resets when the relays turn off the solenoids.
Thank you everyone for the diode education, and advice on re-wiring/correcting the relay approach.
But in practice they are all the same price
1N4001
1N4002
1N4003
1N4004
OK for some odd reason the 1N4003 is slightly more expensive in small quantities. Maybe, as they are out of stock on this one, it reflects the new price to come for all.
Hi,
1N4007 is all you basically need.
All the 1N400X series the same size, and basically the same price.
Tom.... 
I repeat from #67.
I rather suspect they may actually be all the same batches, and sold under different numbers to suit manufacturers' ordering practices.
I could be wrong.
Well the way to find out is to buy a bunch of 1N4001s and measure the reverse breakdown voltage, but I no longer have access to the equipment that would measure that. It was a very large Tetronics network analyser that you had to push round on a trolly. In my undergraduate days in the late 60s.
Wouldn't a current limiting resistor, an oscilloscope, and some line current be enough?
Well given that the spec is to measure the actual breakdown of a rated 400V diode, you would have to be capable of having a variable drive of about 500V, which while doable is not simple. I think you would at least need some sort of step up transformer to do this from the mains.
