voltage selector for microcontroller

Discussion in 'The Projects Forum' started by mik3ca, Jul 16, 2009.

  1. mik3ca

    Thread Starter Active Member

    Feb 11, 2007
    189
    0
    I want to make a programmer for my microcontroller (at89c2051) that can program the chip and verify the code that is on the chip. Until now, I made a basic programmer that does not verify data.

    According to the docs, I will need three voltage levels on the reset pin to take advantage of everything. 0v, 5v and 12v.

    I learned from this circuit:

    [​IMG]

    that I can easily make an inverter from transistors, and I think the transistors can also switch between two voltage levels, But I want to be able to somehow switch between three voltage levels. Is there a simple circuit I can make with the transistors that can accept two digital inputs of about 5V (logic high) or 0V (logic low) that can produce an output of 0V, 5V or 12V that the microcontroller requires based on the input?

    thanks.
     
  2. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    You can get that by using two transistors.

    [​IMG]
     
  3. mik3ca

    Thread Starter Active Member

    Feb 11, 2007
    189
    0
    I will experiement with your posted circuit. thanks.
     
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