Can this work ok as SPDT relay?

Discussion in 'The Projects Forum' started by StupidPig, Jan 6, 2010.

  1. StupidPig

    Thread Starter Member

    Jun 5, 2009
    12
    0
    I'm working on a LED project which require me to seperate an input1 to two different paths based on input2. I been using SPDT relay and it works ok, but I could like to get rid of the relay. I searched the internet and didn't found anything, so I tried with 1 NPN and 1 PNP and it seems working, but I have two questions hoping experts here can answer:

    1. Anything wrong in my circuit which will cause it failed in long run?
    2. At the begining, I'm using a small NPN (2n2222, TO-92) from RadioShack instead of the TIP31 but it didn't work. The NPN flow about 4v even input#2 is open. Why?

    [​IMG]
     
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
    1,758
    98
    What is the load?
     
  3. StupidPig

    Thread Starter Member

    Jun 5, 2009
    12
    0
    For the upper path, it will be split to
    1. drive one 2n6488 npn, which will futher drive 2x 9V Voltage Regulator (2A each max) for superflux LED serials, a 1A Buck driver for two Cree high power LED, and 2 inverter for CCFL.
    2. connect to the base of a PNP (2n4403) and a 10K resistor to GND, to stop the flow of the PNP in a PWM circuit for the Buck driver.

    For the lower path, it will be used to drive the same 2n6488 in #1 above.

    The project is used in the car, so when I say 12v, it is actually between 10v to 15v. I will try to update the schematics with all components to make it clear. Any opinion on which is the easiest software to use for drawing schematics? Drawing with Paint is just pain.

    Thanks.
     
  4. StupidPig

    Thread Starter Member

    Jun 5, 2009
    12
    0
    Does anyone able to answer Q2? I really like to know is it normal for the 2n2222 to allow current flow from collector to emitter even I left the base open. Or it just the small NPN I got from Radioshack are faulty?
     
Loading...