How to tell diodes apart

Discussion in 'General Electronics Chat' started by cheddy, Oct 19, 2007.

  1. cheddy

    Thread Starter Active Member

    Oct 19, 2007
    Hi I went to the store today and was looking to buy some diodes according to a book I am studying. The book mentioned three specific diodes

    1N4001 diode
    OA47 diode
    3v0 zener diode type BZY88

    I went to the store and couldn't find anything resembling the names of the first two diodes. I have no idea what diode specifications are and I guess it doesn't help the book doesn't mention anything about the difference between any two diodes besides their names. Of all the diodes I looked at none were labeled "diodes" they were all either "zener diodes" or rectifiers or some other names I don't remember, none of them resembled the book text.

    What is a good replacement for the diodes prescribed in the book. I'll be making my 4th trip to the store in 4 days hoping to find something but as of now i'm completely lost. Thanks...

    Also how come there are like 50 different types of diodes which all look about exactly the same, how can they all be different, I didn't see any electrical specifications on them that I could understand.
  2. cumesoftware

    Senior Member

    Apr 27, 2007
    The 1N4001 diode is a classical rectifier diode. It is a black diode with a silver strip at one side. Normally these diodes have markings saying 1N4001. It stands a current up to 1A, and a reverse voltage up to 50V. The others I don't know for sure.
  3. cheddy

    Thread Starter Active Member

    Oct 19, 2007
    Thanks cumesoftware. I appreciate you trying to help but that only answered one very small part of my question and doesn't help me at all with the other diode. Are you saying that all black diode with a silver strip will all work the same and they aren't really different?
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    Not at all. The 1N4001 is a rectifier. The last diode on the list is a zerer, that operates under reverse breakdown and acts as a voltage regulator. It will not make a rectifier.

    I have no idea about the OA47, but some searching on Google will bring up some information, as it would have about the other two.
  5. Elektronster

    New Member

    Oct 19, 2007
    The 1N4001 is a common 50 volt rectifier diode. Most suppliers should have them--even Radio Shack! '4002, '4003 and '4004s are all good substitutes if you can't find the real thing. The OA47 is a British germanium diode, very similar to a 1N34. It has a forward voltage drop of around 0.3 V and a peak reverse voltage rating of 75 volts or so. The BZY88 is also European, I think. A US equivalent would be a 1N5226B or 1N4728A, although both of those are rated at 3.3 volts zener voltage. It would be a good idea to start a cross-reference notebook to keep this kind of information handy, in case you ever need to refer to it again in the future.
  6. Papabravo


    Feb 24, 2006
    Sadly for you, in your current situation, there are as many different types of diodes as there are cross ties on the railroad tracks. The good news is that Google is your friend. Try the following searches"
    1. "1N4001 datasheet"
    2. "Oa47 datasheet"
    3. "BZY88 datasheet"
    It may help to restrict the results to the Adobe PDF format since most all manufacturers post their datasheets in this format. Then you need to start understanding what the numbers on the datasheet mean. Pay no attention to the size and the color, they mean nothing. I have a batch of 1N4001 in green plastic with no stripe. They are cone shaped on one end however.

    If you are really in a hot bother to mess about with diodes buy a hand full and characterize them yourself. This requires a some resistors, a power supply and two meters. Take a set of current and voltage readings and plot them up. Use a different color for each diode and plot the results so you can see, that even members of the same family have noticeable differences.
  7. SgtWookie


    Jul 17, 2007
    Try these websites for datasheets:

    There are a number of other search sites as well - one of the forums has a resource thread stuck to the top; many are listed in there.

    Just knowing where to look is a good part of the battle. ;)

    BTW, Radio Shack sells an assortment of 1n400x-type rectifiers; 25 of them for a couple of bucks. The assortment I bought came with 1N4001's, 1N4002's 1N4004's and 1N4007's; 10 of the 4001's and 5 of each of the others.

    You might want to start out by building yourself a regulated power supply. You will ALWAYS have a use for it!
  8. cumesoftware

    Senior Member

    Apr 27, 2007
    No. There are several rectifier diodes that use the same design, but have different markings. For example, the 1N5400 diode. So they are really different. As I said, you have to see it they have markings on them. But if you can't get a 1N4001, you can replace it by any diode of the 1N400X series. They are not exacly the same, since they have different voltage ratings, but they won't be inferior to the 50V reverse peak voltage of the 1N4001 diode.

    Also, I didn't replied to the rest of your question because I'm not sure about the other diodes. It is rather preferable than answering wrong. The forum guidelines infere that I don't have even the obligation to answer your question. You should read them since they really give you useful tips on how to adress to people.

    "Irrespective of the egos on the board, it’s not someone else’s privilege to troubleshoot your circuit or your misunderstanding of the theories. The members here are doing you a favor. If no one answer’s your inquiry very fast, consider this is a worldwide resource and some may be sleeping or at work.

    Being snippy or rude will only stop people from responding and lead to your query being flamed."

    I guess that aplies to partial answers too.
  9. Nomad

    Active Member

    Oct 21, 2007
    woah. um, i didn't see anything disrespectful or demanding there, and they did say thank you. maybe someone had a long day? mis understood? (old animals song, please dont let me be mis understood. ok i'll spare you all my singing) Did i miss something? lol