Transistor Replacement Help Needed

Discussion in 'General Electronics Chat' started by Leckyuk, Feb 3, 2011.

  1. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Have you tried Farnell UK?
    Fairchild Semiconductors' KSB1151 looks pretty much equivalent; Vce=60v, Ic=5A. The original 2SB1161 claims a low saturation voltage for low power dissipation in the transistor; it's rated for 1.3 Watts, TO-126 (similar to) package.
    A ZBD953 is somewhat similar, but has less collector current rating. (4A vs 5A)
    You might check RS Components, too.

    Is this to fix something, or a new project?
     
    Last edited: Feb 3, 2011
  3. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    Hi and thanks for the reply. This is part of an ongoing project. I have posted a few other threads regarding my digital jukebox project which is now complete. The only thing is I set up a circuit to use a coin acceptor but the output pulse that the acceptor gives off when a coin is inserted is absolutely tiny. It runs at 5volts and 65mA so cannot activate the solenoid in the smallest mini relay I can buy. I knew nothing about electronics until i had some help on here. In the end I set up a second loop from a 5volt feed on a PC PSU and just attached a transistor that I ripped out of an old Ipod dock. Unbeleivably the transistor was perfect, once the 65mA pulse hits the transistor it switches on the larger Ampered 5volt circuit and is plenty strong enough to activate the relay.

    The only problem is it was all done a bit cheaply and all just attached to the end of lon wires which are everywhere. I have completed a small project box with circuit board inside but I had trimmed the pins on the old transistor to get them to fit the old circuit and now they are not long enough to get through the circuit board.

    Ideally I just want to walk into maplin and pick up something that does exactly the same job as the transistor I have here. The only thing I have changed though on suggestion from some people on here is that the 5volt circuit which powers the relay has now been changed to 12volt. I was running two supplies into the project box at 5 and 12 volt as the coin acceptor runs off 12 volt. For simplicities sake i just used the one supply and bridge it over.

    If someone could point me in the right direction I would really appreciate it.
     
  4. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    Would anyone know if one of the following would be suitable for replacing the transistor?

    Specifications:
    Type VCEO IC PTOT Case
    V A W Style
    BD442 -80 -4 36 TO126
    BD912 -100 -15 90 TO220
    TIP2955 -60 -15 90 TO218
     
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    As I said in post #18, here, 5V@ 65ma is more than enough to drive your relay. It only requires 5V/Rcoil=5V/180Ω=28mA.
     
  6. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    Thanks again for your post Ron. First thing I should mention is the spec of the coin acceptor is roughly estimated at best! It's from hong kong soothe amperage I'm quoting may well be the working amperage of the acceptor it's self, not the pulse it emits. Most importantly the first thing I tried was to see if the pulse is enough to drive the relay and it is not. Secondly, after hours of trying to get it to work in various configurations, it now works perfectly with the transistor circuit in place.

    As I don't understand all the figures that are on the data sheet, I just simply don't know what duplicate transistor to buy. I hope one of the ones I've mentioned previously would be suitable. What do you think??
     
  7. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    If anyone gets a chance, could you have a look at the transistors on this page and tell me if any are suitable. I have also inculded the Diagram of the circuitry kindly ammended by some members on here.

    http://www.maplin.co.uk/search?criteria=transistors

    If there is anything on there that you think might work then can you kindly make a post.

    Many Thanks.
     
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