Counter

Discussion in 'General Electronics Chat' started by NM2008, Jan 10, 2012.

  1. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
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    Hi there.
    Just wondering could somebody give me name/code for a counter ic.

    What i am looking to do is to count to 5. But the counter must remember where it is in the count once power is removed from the ic.

    For example, say 5 leds, each led lights on a single pluse. So if it has 3 leds lighting and power is removed, once power is reapplied it must relight the 3 leds and continue the count from where it stopped.


    Thanks for the help.
    Regards NM
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    This is like a bargraph? Count 1 lights the first LED, count 2 the second LED (while the first remains ON) and so on. Is that correct?

    In that case you can use a 40174 FF similar to what I posted here, with a few modifications though.

    Tell us the exact sequence you want and where the pulses come from and on what edge you want to trigger.

    The CMOS IC itself needs to have a small lithium backup battery.
     
  3. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
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    Yes is that is correct.

    The counter is for a project that will be in use for a few years. I was trying to keep away from battery backup, to avoid having to build a complicated recharge circuit.

    It can trigger on either rising or falling edge it is not critical for this application.

    Is there any ic that can store the count in a memory without the need for external power?

    Regards NM
     
  4. BillB3857

    Senior Member

    Feb 28, 2009
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  5. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
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    BillB3857

    Thanks for the link, but its a little over my head, (im from a mechancial eng background and have a limited knowlegde in electronics.)

    Basically I need to know is there a counter out there that remembers/records its count, and is capable of remembering it when power is removed, preferable all in the one package.

    For example an 8 pin/leg ic where say pin 4 is the remember function. So when in the middle of a count and is powered off pin 4 goes low and records the count. Once power is reapplied pin 4 goes high and the count continues.

    Is there such an ic?


    Regards NM
     
  6. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    That looks more like as if it would involve a uC and a non-volatile memory, not a single IC.

    Battery backup for years for a CMOS IC is possible without problem, they draw very little power.
     
  7. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
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    praondevou

    How would I impliment a battery backup. Are you referring to a rechargable battery and circuit, or a just a single non rechargable button cell?

    Thanks
     
  8. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    A single non rechargeable button lithium cell. I can draw something up later.
     
    JCOX likes this.
  9. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
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    praondevou

    One more qeustion, I take it that this battery would need to be switched out each time the external power is applied to the circuit to avoid the external power from trying to charge it. Would that be correct?

    Thanks
     
  10. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    One way to do it is to have a Schottky diode between the battery and the IC to run the IC counter value. CMOS IC's pretty much only use power when switching. Sometimes more elegant solutions such as a MOSFET are used to switch to battery power, but for your simple app, and only one IC that needs to be "kept alive", that should do, as long as the minimum voltage is 2.5V.

    When power is applied, the battery would be out of the circuit since the diode would be reverse biased. The main power would also connect to the LEDs, etc.
     
  11. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    The flipflop in the middle is actually 5 single flipflops. I don't have single FFs in my simulator. Their clocks are tied together, that's the CP input.

    1st pulse, the 1st output goes HIGH, next pulse the 1st remains ON, the second goes HIGH too. and so on.

    I looked up some components on digikey which I think would be suitable.
    The circuit should be good for 2 to 3 years with the battery I indicated.

    The input can of course not remain open when not in use. It needs to be tied to Gnd via a resistor or the component you get your trigger signal from. You also didn't say what will be the power supply voltage and how you want to reset the circuit.

    The LED resistor values depend on the LED you choose.

    schottky
    http://search.digikey.com/us/en/products/NSR0140P2T5G/NSR0140P2T5GOSCT-ND/1967249

    flipflop
    http://search.digikey.com/us/en/products/SN74LVC1G79DBVR/296-9849-1-ND/380105

    battery
    http://search.digikey.com/us/en/products/CR2430/N603-ND/704860

    MOSFET
    http://search.digikey.com/us/en/products/IRLML2803GTRPBF/IRLML2803GTRPBFCT-ND/2354247

    [​IMG]
     
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  12. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Does the OP know how to etch a PCB?

    All the parts listed are surface mount.

    It can be done with through hole as well, for a little bit more, then use perf board to wire it up.

    If the OP wants to make his own board, surface mount is the easiest if you have a flux pen and a fine tipped soldering iron. There are no holes to drill!

    If you use perfboard, they can get ugly looking, but work.
     
  13. praondevou

    AAC Fanatic!

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    Unfortunately he didn't say. :)
    Nowadays SMDs are so much easier to get. He could also use SMD protoboards... I thought this would be a mobile application with space limitations... He will tell us.
     
  14. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
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    Hi,

    He is back! :)

    praondevou
    Thanks for taking time to list the components and drawing the schematic, very helpful I can now see arrangement that thatoneguy was referring to previously.

    Out of curiosity, how do you calculate the battery size for an application like this? Is it almost like a rule of thumb with respect to component size and power consumption. Can it even be calculated without knowing cycle times?

    Thanks
     
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