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ArcticMyst Security by Avery

Diode difference please advise

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Dec 18, 2009
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I built a LM317 based driver for my PHR bluray diode. Now the circuit I am following requires a 1N5817 silicone diode. Will the 1N4001 work in place of it? I can't find these 1N5817 diodes locally, but I do have plenty of the 1N4001 diodes. Any input is appreciated. Thanks.
 





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Sep 6, 2009
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A 1N5817 has a Vf of about 0.4v, whereas a 1N4001 drops about 0.7v. Depending on how the diode is used in your circuit, the 0.3v Vf difference might not matter, or it could prevent the circuit from functioning entirely. If you are using the diode as reverse polarity protection in a LM317 circuit, it shouldn't matter which diode you choose (as long as it can handle the reverse bias and current). If you are using the diode as an ESD suppressor then you cannot substitute a 1N4001.
 
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Thanks that makes sense. I am only using it in the LM317 circuit for reverse polarity protection.(I think.)
 
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For reverse polarity it will not matter as long as your diode can take the voltage and current, the less forward voltage it drops the less power it will take from the ckt, this is why mosfets are used for reverse polarity protection you might think about using one of them in it's place.

Flaminpyro...
 
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Well that kind of confused me. I have built plenty of red burning lasers with Daedal's LM317 circuit with no problem. My concern was when I saw a revised circuit using a blu-ray LD instead. The difference was the silicone diodes used. For blu ray it is calling for a 1N5817 diode, whereas the red LD calls for a 1N4001. Sorry if I sound as if I am repeating myself, I just want to know if I can use the 1N4001 in my blu-ray build instead of the 1N5817 diode?
 
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So can anyone please confirm weather or not I can use the 1N4001 diode instead of the 1N5817 for my blu-ray build?
 
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Like I mentioned above, if you are using the diode for reverse polarity protection, substituting a 1N4001 should be okay. If you are using it for something else then I cant say for sure whether a substitution is possible.
 
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Jul 26, 2009
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1n4001 should work make a test load first then test your driver with it. good luck
 
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Here is the circuit I am referring to....
 

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That doide is used for reverse current protection. The 1N5817 is a Schottky diode which are high speed. For that reason it is better than the 1N4001 for this purpose. I don't have the experience hooking up drivers backwards so it's hard to say if the higher speed is necessary. I did use a Schottky diode in my http://laserpointerforums.com/f51/make-your-airsoft-tracer-ready-blu-ray-44775.html#post596171 because it was hooked up to the same circuit as the guns motor which sends revise current down the line as the fields collapse around the motor when power is cut off.
 
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Yes, I found it locally. Last one in stock.:yh: It is in fact a Schottky Barrier Diode that is fast switching. Thanks for your help though.
 




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