I read atleast 3 or 4 topics about diodes but in none of them actually I found something useful.
I just want to have a diode. Common diode 
I will be using it sometimes for rectification (max 24V), as a flywheel (for reverse motor shitty things) and for similar things that just require something to prevent for wrong placed "+" and "-" wires. I read about 1N4001 and did a google search plus I viewed its datasheet, but it says that there are "stronger" diodes - 1N4002 to 1N4007... And I got confused...
So would you please suggest me a proper diode? Thanks in advance.
The difference types are all 1amp diodes but have different reverse breakdown voltages .
There is little price difference so buy IN4007 - 1000v
The two most important specs are forward current and reverse voltage. I usually buy a higher voltage version (1N4007) since they don't cost much more and I'm usually buying more than I need so I don't know what I'll be using them for.
As a flyback (or flywheel) application the (peak) current through the diode will be the same as the current through the motor/coil, and the reverse voltage will be the applied voltage.* (So, in most low-voltage applications, voltage isn't an issue and you just have to check the current.)
I will be using it sometimes for rectification (max 24V)
When I'm building a power supply I usually use a [u]bridge rectifier[/u] which is 4 diodes in one package. I may have made a bridge from 4 1N4001's, but I don't remember. With a single diode, the power is "off" for half of the AC cycle which means you get more ripple (or you have to use a bigger capacitor) and you can only get half the current.
Or, if you have a center-tapped transformer you can get full-wave rectification with two diodes.
The forward voltage across a standard silicon diode is about 0.7V (depending on current) and in some applications where you want a smaller voltage drop, you can use a Schottky diode. Schottky diodes also switch faster than standard silicon diodes so they are sometimes used in high-frequency circuits.
- When you disconnect an inductor/coil you get a high-voltage kick (back EMF). But, since the diode is "backwards", that back EMF becomes the forward voltage across the diode. That "kills" the high-voltage kickback, and your diode never sees high voltage.
Forward voltage is also important. As a rule of thumb more rated current means less forward drop for fixed current (i.e. 1A rated diode has lesser forward drop than one rated for 200mA when you pass 100mA). Schottky diodes have smaller forward drop but higher leakage current - they are better in low voltage "power" applications than normal diodes. Examples are BATxx diodes (BAT85).
So should I buy Schottky or normal one?
It depends what you want to do. Most of the time it is probably not so important. If you have supply voltage 20V or more it is not so important if the diode drops 0.7 or 0.3V. If motor needs 1A you don't care if diode leakage is 1mA or 10uA. If you want something more delicate such as reverse voltage protection difference between normal and Schottky diode may be more important if the battery voltage is close to your intended operating voltage. OTOH if you build some analog circuit "large" leakage current of Schottky may cause problems.
Another important spec - diodes rated for large current are also large - they have thick leads and they are difficult to stick into solderless breadboard. I even got diodes too thick to fit into hole in protoboard.
These three through-hole diodes will cover most low voltage low current needs.
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1N4148
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1N4004
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1N5819
Leo..
Smajdalf:
Another important spec - diodes rated for large current are also large - they have thick leads and they are difficult to stick into solderless breadboard.
Is the 1N4007 too thick or i should go for 1n4001?
The through-hole versions of the 1N4001 to 1N4007 are all the same size.
They are all rated for 1Amp continuous.
Only the reverse voltage is different.
I suggest you buy the 1N4004 instead of the 1N4001.
The xxx5 to xxx7 should only be used for high voltage (mains), since they have a slightly higher forward voltage.
That is however not a big issue in 'most' applications.
The bigger (3Amp) version of the 1N4xxx starts with a '54'.
e.g. 1N5404.
Leo..