Connect with us

Solid state SPDT?

Discussion in 'Electronic Basics' started by EROMLIGNOD, Aug 2, 2003.

Scroll to continue with content


    Hi guys:

    What is the best way to get an SPDT effect using transistors/chips?

    Here's my problem. I have over 200 little circuits to address. They are all
    hooked to the same square wave output. I poll them one-at-a-time and switch
    them from the square wave line to a common input line to my MPU and measure a
    wave coming FROM them. Then I switch them back and go on to the next circuit.
    Think of it like an SPDT switch with the common leg connected to the circuit,
    one leg connected to the output bus and one leg connected to the input bus.

    I realize there are ways to do this with discreet transistors, or single switch
    circuits. Isn't there an economical way to do the 219 circuits with a
    transistor array, or some type of off-the-shelf chip?

    All replies are greatly appreciated.

  2. Do you have development control of the 200 circuits themselves?
    If so, design them such that their outputs can be tristated (hiz) and a
    control input and a control output on each along with a common clock. Wire
    the circuits up bucket brigade style (like a serial shift register). You can
    then clock in a serial bit stream to select which device you want driving
    its output. A single d-type FF and a tristate buffer circuit per device can
    do this.

    There's a lot of ways to implement this including the control scheme.

    Hope this helps.
    Dana Raymond
  3. MAG

    MAG Guest

    It would help to know about the voltages and currents you expect to see.
    But here are some chips you can look at.
    4066 & 4016- are Quad Bilateral switches [ 4 spst]
    4051- is a Single 8-channel analog Multiplexer/Demultiplexer [like a 8 pole
    rotary switch]
    How do you want to pole each switch? Do you want to do it randomly or in
    sequence with a count down/up circuit?

Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day