IN4001 Question.

Mohrenberg · Jan 20, 2011

Alright so today i went to build my own test load.
through some sort of miracle i actually remembered that it calls for in4001 diodes. So i was grabbing them and noticed on the packing that they list the voltage drop as 1.6v
So why is it we use 4 of them for a red diode? that comes to 6.4v when a red diode only requires 3v.

Am i missing something? did i pick up the wrong diodes?
If someone could explain this to me it would put my mind at ease.

rhd · Jan 20, 2011

Are they from RadioShack?

I seem to remember a thread on here about RadioShack in4001s having different specs on the packaging.

Mohrenberg · Jan 20, 2011

Yes they are.
So are they still good?
is the packaging mislabeled or what. I guess i should just buy a test load from jeffrey.....

AUTO XX · Jan 20, 2011

If you are doing high power builds I'd recommend the 1N540* diodes as well as a 2W resistor.
Mine handle the heat with ease, the 1N400* one heat up in a few seconds with my 1st 445nm build

*I also wouldn't trust anything radio shack (the source) says in the spec sheet.

LarryDFW · Jan 20, 2011

Mohrenberg;

The voltage across the 1N4001 should be ~0.75 VDC at the current of the test load.

Voltage is dependent on temperature.

Even the Radio Shack 1N4001's should be OK.

LarryDFW

rhd · Jan 20, 2011

I've got a ton of in4001s that I know work in a test load. I'd be happy to drop some in an envelope and send them in your direction.

AUTO XX · Jan 20, 2011

Goes up when you apply a higher current.
I don't know the specs but I think it's around 1V at 1.5A+

Coherent Light · Jan 20, 2011

Matt I just metered 10 Rat Shack 1N4001's and They all come in around .5v-.6v. I would just put them in series and meter them until you get the right voltage drop.

Kookapeli · Jan 20, 2011

I thought that any 1N400* diodes the voltage drop was .7 bu the higher the last number the more V's it can withstand ???

Coherent Light · Jan 20, 2011

The package says 1.5v but We all know the drop should be around .7v. I don't know why these meter low, but they are consistent. I'll run more tests on them tomorrow as I have 25 to play with.

HIMNL9 · Jan 20, 2011

Dropout in diodes is dependent from the current that you flow through them.

1N400X serie is 0.7V AT 30mA, approximatively, 0.75V AT 50mA, and so on, it become around 1V at 1A.

LaserAdct · Jan 20, 2011

If I recall correct the 1N4001 diodes can handle a max of 1A, so if higher current is needed go for the 3A diodes - I think they are 1N4007 but not sure if my memory is correct

HIMNL9 · Jan 20, 2011

No, sorry, all the 1N400x serie can handle only 1A (and dissipate 1W max), the difference is in the maximum reverse voltage (from 100V of 1N4001 to 1000V of the 1N4007)

for 3A, you need the 1N540X serie, or equivalents.

Benm · Jan 21, 2011

HIMNL9 said:
Dropout in diodes is dependent from the current that you flow through them.

1N400X serie is 0.7V AT 30mA, approximatively, 0.75V AT 50mA, and so on, it become around 1V at 1A.

That sounds about right

There will be a slight increase in forward drop between tn4001 and 1n400, but that is really marginable.

rhd · Jan 21, 2011

The takeaway - we should be using 5x of these diodes instead of 6x in test loads for 445nm builds (assuming around 1A).

Here's a graph (also attached in case the URL dies):

From this extremely complicated explanation that I'm not going to read

1N400x Diode Family Forward Voltage

Benm · Jan 22, 2011

It depends a bit, but at these currents i usually count 1n400x diodes as 1 volt each, and in540x ones as 0,8 volts or so.

All of these are intended as rectifier diodes though, not as voltage references, so they exact drop at a given current can and will vary between manufactureres. I'd look at the typical values stated to get idea, those are usually better than stated maximum voltage drops.

IN4001 Question.

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