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What the latch?

Discussion in 'General Electronics Discussion' started by BeagleFaceHenry, Jan 16, 2017.

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  1. Pyramid

    Pyramid

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    Jan 17, 2017
    Please see post #11 above. If I read the OP correctly, he wanted a simple set/reset type flip-flop which this circuit provides. It may be simpler to use a octal latch i.e. 74273 types, but they don't have individual sets/resets.

    The 74 series has higher current variants (AC), but they are limited to 5V supplies (I think the OP was looking for 9/12V capability). The 4049 or 4069 is a hex inverter, but w/o schmitt trigger inputs. AFAIK, the 40106 is the only version that meets his requirements.
     
  2. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    I think perhaps they were thinking of wiring pairs of them as RS latches. See @Pyramid's post #11. I've done this many times, usually for de-bouncing SPDT switches... and you don't need the resistors shown in the schematic.
     
  3. BeagleFaceHenry

    BeagleFaceHenry

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    Nov 11, 2016
    May I ask, what's the functional difference (or similarity) between a flip flip and a hex inverter?
     
  4. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    A flip-flop (NOT a flip flip, whatever that is) retains either of two stable output states and thus exhibits memory.

    A (hex) inverter responds in real time to an input logic state by inverting that state without any memory of previous states: Thus if input = 1, output = 0; if input = 0, output = 1. In a hex inverter there are six of these logic elements, all acting independently.
     
  5. BeagleFaceHenry

    BeagleFaceHenry

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    Nov 11, 2016
    Ok, I'm still working on this one, thanks to anyone who is still hanging on.
    Great catch Hevans, thanks for the info. A hex inverter is nothing like a flip flop.

    I have another question. I have a 9v wall wort that I'm using as a power supply. Most of the flip flops I see are rated for only 5v. I've seen a little 5v regulator (3 pin chip) at Radio Shack for a couple dollars. Is that 5v regulator chip what I need to protect my 5v flip flops from my 9v supply, or am I deluding myself once again?
    Thanks!
     
  6. Minder

    Minder

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    Apr 24, 2015
    I have a flip-flop circuit using one P.B., two relays 3 diodes and a cap.
    M.
     
  7. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    Yes. I frequently use one for just that purpose when prototyping with 5 V TTL logic devices. If you use CMOS logic devices, they can be powered directly from your 9 V wall wart. Or you can "roll your own" flip-flop from discrete components as Minder suggested.
     
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