Author Topic: 1N4148 / 1N914 Diode difference?  (Read 5647 times)

dustbro

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1N4148 / 1N914 Diode difference?
« on: September 17, 2006, 05:27:13 AM »
Looking for some 1n4148 diodes to finish off my Gssl... I noticed that Radio Shack has their diode box labeled as "1N914/1N4148-type diodes case DO-35".  Are both of the these the same thing? or is this something I should stay away from?
thanks
Dan


Samuel Groner

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1N4148 / 1N914 Diode difference?
« Reply #1 on: September 17, 2006, 07:07:31 AM »
A search is as always pretty helpful:
http://www.groupdiy.com/index.php?topic=14422
starts at page 3, bottom.

Samuel

dustbro

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1N4148 / 1N914 Diode difference?
« Reply #2 on: September 17, 2006, 12:47:12 PM »
Thanks Samuel,
I have already read thru that post, but to me it doesnt make it clear if  they are interchangable... or what the specific effect will be on the GSSL. although looking at the specs of the 914/4148 package from Radio Shack  it says it operates at 75V, which doesnt meet the required 80V listed on the ssl, so I'm going to have to assume that these cannot be used.
thanks
Dan

gyraf

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1N4148 / 1N914 Diode difference?
« Reply #3 on: September 17, 2006, 01:07:20 PM »
Why would you request 80V for the SSL? As I see it, the maximum voltage - anywhere in the circuit - won't exceed some 35V?

Jakob E.
..note to self: don't let Harman run your company..

dustbro

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1N4148 / 1N914 Diode difference?
« Reply #4 on: September 17, 2006, 01:39:06 PM »
Quote from: "gyraf"
Why would you request 80V for the SSL?

I believe that was listed as a requirement on the parts list I downloaded.... but I'm very new at this, so I wouldnt know how to figure out the maximum voltage on my own yet. thanks for clearing that up. So now, the 914 can handle between 10mA and 75mA (500mA peak) and the 1n4148 can handle between 100-200mA. Anyone know what difference this would cause in the ssl circuit? I've read on other forums that you can swap out the 4148 for a 914 in MOST applications... would this be one?
thanks for all
Dan

gyraf

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1N4148 / 1N914 Diode difference?
« Reply #5 on: September 17, 2006, 01:52:26 PM »
It's not a voltage requirement - it's the component's spec...
..note to self: don't let Harman run your company..

Samuel Groner

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1N4148 / 1N914 Diode difference?
« Reply #6 on: September 17, 2006, 03:14:24 PM »
Quote
But to me it doesn't make it clear if they are interchangable...

Yeah, they are, in fact it is the same part.

Samuel

bcarso

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1N4148 / 1N914 Diode difference?
« Reply #7 on: September 17, 2006, 04:49:09 PM »
Agree; the vast majority of nominal small-signal fast Si diodes are tested and selected from the same chip.  National Semi called it their process D1.  

Exceptions:  the low-leakage types (FDH300 and others), really fast low voltage (FD700), and a few others.

Bear in mind, though, that if you meet JEDEC specifications you can sell something as a JEDEC numbered part, even if the construction and other characteristics not listed in the spec are different.

tommypiper

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1N4148 / 1N914 Diode difference?
« Reply #8 on: September 17, 2006, 06:54:52 PM »
I've also been wondering about these diodes.  They are clear glass.  Are they affected by light?
Imagine a wet, slightly chilled from its gas release and decompression, with water droplets condensing, sucking surface tension, slowly sliding down the side, capped by a healthy virgin froth on top..

bcarso

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1N4148 / 1N914 Diode difference?
« Reply #9 on: September 17, 2006, 09:26:07 PM »
Quote from: "tommypiper"
I've also been wondering about these diodes.  They are clear glass.  Are they affected by light?


Yes, glass diodes are photosensitive.  They are not terribly good photodiodes but depending on the circuit it can become important.

LEDs are also photosensitive, appreciably less so.  The shorter-wavelength emitters are a good deal less sensitive to visible light than the longer; blue LEDs are essentially blind to everyday anthropogenic sources, from what I've measured.  Red emitters I've actually tried using as cheap photodetectors, otoh.

(EDIT: corrected a misused word)


Gus

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1N4148 / 1N914 Diode difference?
« Reply #10 on: September 17, 2006, 10:04:23 PM »
In the Mims books there are circuit using leds as detectors IIRC.

PRR

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1N4148 / 1N914 Diode difference?
« Reply #11 on: September 17, 2006, 10:46:52 PM »
> you can swap out the 4148 for a 914 in MOST applications...

I remember when the 4148 was the "improved" 914, and cost more.

As bcarso says, today any diode costs less than a grain of rice, so they probably don't make 914 parts any more, just the 4148 part.

I'm not sure the 60V spec on 914 was ever "real". Back when there were "real" 914s cheaper than 4148, I needed some 80V-90V Zeners. I had heaps of 914s. I started testing then for Reverse Breakdown: at 0.5mA, they all zenered at 110V to 130V. OK, maybe the leakage rose at 60V, I didn't test that. But the uniformity told me they were doped for 100V +20% safety factor, even though sold as 60V parts.

I don't see where any of the GSSL's diodes sees even 10V reverse voltage (some less than 1V), or where a microamp of leakage would bother anything. You can use about any hunk of silicon. If you happened to have a sack of transistors in hand, you could use their C-B junctions.

dustbro

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1N4148 / 1N914 Diode difference?
« Reply #12 on: September 17, 2006, 11:30:06 PM »
Thanks for the great info guys!  I feel that I'm am much more schooled in this subject than I was a week ago. great thread
Dan

techguy56

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Re: 1N4148 / 1N914 Diode difference?
« Reply #13 on: January 19, 2014, 03:49:06 PM »
In the 914/1n4148 topic, here in 2014, while doing new manufacturing and repairing, we have been using the 1n914 and 1n4148 diodes in the same spots. Only "Supply" determining which one we put in. We would request 1n4148 and get it but if they were out... we get 1n914. 


 

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