Frequency divider (divide by 100)

Discussion in 'Electronic Basics' started by sck0006, Mar 26, 2006.

  1. sck0006

    sck0006 Guest

    I need to make a phase stable divide by 100 frequency divider. The
    input signal is 10Mhz, and I need 100kHz output. Phase shift isn't
    important, as long as it is stable. Should a 74HC390 do the job?

    If so, the 10MHz input is around 2-3VRMS, and I need to get a TTL
    level square wave to input to the ripple counter, correct? Any
    suggestions about how to do that?

    Is there another EASY way to go about doing this (i.e., no assembly
    language, I'm pretty poor at writing code).

    If it helps, I'm trying to check the accuracy of the variable phase
    portion of a 3325b. In the manual it calls for another signal
    generator at 100kHz, and measure time interval between the uut and
    other std. The problem I'm having is none of our signal geneartors go
    down that low, besides the 3325b. I'd like to just divide the 10MHz
    reference and use it as the other signal, but frequency must be exact,
    and there can't be any phase drift. There should be no frequency
    error (negligable would be more proper) with a divider, should there?

    All suggestions appreciated.

    Thanks,
    Steve
    sck0006, Mar 26, 2006
    #1
    1. Advertising

  2. <sck0006> schreef in bericht
    news:...
    >I need to make a phase stable divide by 100 frequency divider. The
    > input signal is 10Mhz, and I need 100kHz output. Phase shift isn't
    > important, as long as it is stable. Should a 74HC390 do the job?
    >
    > If so, the 10MHz input is around 2-3VRMS, and I need to get a TTL
    > level square wave to input to the ripple counter, correct? Any
    > suggestions about how to do that?
    >
    > Is there another EASY way to go about doing this (i.e., no assembly
    > language, I'm pretty poor at writing code).
    >
    > If it helps, I'm trying to check the accuracy of the variable phase
    > portion of a 3325b. In the manual it calls for another signal
    > generator at 100kHz, and measure time interval between the uut and
    > other std. The problem I'm having is none of our signal geneartors go
    > down that low, besides the 3325b. I'd like to just divide the 10MHz
    > reference and use it as the other signal, but frequency must be exact,
    > and there can't be any phase drift. There should be no frequency
    > error (negligable would be more proper) with a divider, should there?
    >
    > All suggestions appreciated.
    >
    > Thanks,
    > Steve


    A 74HC390 will do, but you'll need a high speed comparator to obtain a good
    logic clock signal. Consider an NE529 or a MAX975. A circuit like this will
    have no drift but you may encounter jitter. This will mainly depend on the
    quality of your input signal but may be influenced by the comparator
    circuit.

    petrus bitbyter
    petrus bitbyter, Mar 27, 2006
    #2
    1. Advertising

  3. sck0006

    Chris Guest

    petrus bitbyter wrote:
    > <sck0006> schreef in bericht
    > news:...
    > >I need to make a phase stable divide by 100 frequency divider. The
    > > input signal is 10Mhz, and I need 100kHz output. Phase shift isn't
    > > important, as long as it is stable. Should a 74HC390 do the job?
    > >
    > > If so, the 10MHz input is around 2-3VRMS, and I need to get a TTL
    > > level square wave to input to the ripple counter, correct? Any
    > > suggestions about how to do that?
    > >
    > > Is there another EASY way to go about doing this (i.e., no assembly
    > > language, I'm pretty poor at writing code).
    > >
    > > If it helps, I'm trying to check the accuracy of the variable phase
    > > portion of a 3325b. In the manual it calls for another signal
    > > generator at 100kHz, and measure time interval between the uut and
    > > other std. The problem I'm having is none of our signal geneartors go
    > > down that low, besides the 3325b. I'd like to just divide the 10MHz
    > > reference and use it as the other signal, but frequency must be exact,
    > > and there can't be any phase drift. There should be no frequency
    > > error (negligable would be more proper) with a divider, should there?
    > >
    > > All suggestions appreciated.
    > >
    > > Thanks,
    > > Steve

    >
    > A 74HC390 will do, but you'll need a high speed comparator to obtain a good
    > logic clock signal. Consider an NE529 or a MAX975. A circuit like this will
    > have no drift but you may encounter jitter. This will mainly depend on the
    > quality of your input signal but may be influenced by the comparator
    > circuit.
    >
    > petrus bitbyter


    And if you're using a single supply comparator like the MAX975, you may
    want to use the HP3325B auxillary Sync Output (square wave output, HI
    >=1.2V, LO >= 0.2V), and be sure to terminate using a 50 ohm resistor. That square wave has great rise and fall times for your comparator conversion to TTL and then the HC390 (remember, /2 last if you want a 100KHz square wave).


    Don't worry, it's digital -- there will be _no_ frequency error from
    the /100 section. Your propagation delays should be consistent too.

    Good luck
    Chris
    Chris, Mar 27, 2006
    #3
  4. sck0006 wrote:
    > I need to make a phase stable divide by 100 frequency divider. The
    > input signal is 10Mhz, and I need 100kHz output. Phase shift isn't
    > important, as long as it is stable. Should a 74HC390 do the job?


    Yes indeed.

    > If so, the 10MHz input is around 2-3VRMS, and I need to get a TTL
    > level square wave to input to the ripple counter, correct? Any
    > suggestions about how to do that?


    Correct. You need a comparator to give you a square wave for your 390.
    I've done exactly that with a MAX4212, but there are plenty of others
    that will work fine.

    > Is there another EASY way to go about doing this (i.e., no assembly
    > language, I'm pretty poor at writing code).


    You already have the easiest way.

    > If it helps, I'm trying to check the accuracy of the variable phase
    > portion of a 3325b. In the manual it calls for another signal
    > generator at 100kHz, and measure time interval between the uut and
    > other std. The problem I'm having is none of our signal geneartors go
    > down that low, besides the 3325b. I'd like to just divide the 10MHz
    > reference and use it as the other signal, but frequency must be exact,
    > and there can't be any phase drift. There should be no frequency
    > error (negligable would be more proper) with a divider, should there?


    Correct.
    There should be no frequency error, no phase error, and no drift error.
    You will however get a small amount of jitter on top of what your 10MHz
    source signal already has, but that won't be an issue in your case.

    I have done this to characterise the long term drift of a DTCXO
    oscillator module using a 10MHz sine wave Rubidium frequency standard.
    Email me if you want the circuit.

    Dave :)
    David L. Jones, Mar 27, 2006
    #4
  5. sck0006

    sck0006 Guest

    On 26 Mar 2006 16:19:18 -0800, "Chris" <> wrote:

    >
    >petrus bitbyter wrote:
    >> <sck0006> schreef in bericht
    >> news:...
    >> >I need to make a phase stable divide by 100 frequency divider. The
    >> > input signal is 10Mhz, and I need 100kHz output. Phase shift isn't
    >> > important, as long as it is stable. Should a 74HC390 do the job?
    >> >
    >> > If so, the 10MHz input is around 2-3VRMS, and I need to get a TTL
    >> > level square wave to input to the ripple counter, correct? Any
    >> > suggestions about how to do that?
    >> >
    >> > Is there another EASY way to go about doing this (i.e., no assembly
    >> > language, I'm pretty poor at writing code).
    >> >
    >> > If it helps, I'm trying to check the accuracy of the variable phase
    >> > portion of a 3325b. In the manual it calls for another signal
    >> > generator at 100kHz, and measure time interval between the uut and
    >> > other std. The problem I'm having is none of our signal geneartors go
    >> > down that low, besides the 3325b. I'd like to just divide the 10MHz
    >> > reference and use it as the other signal, but frequency must be exact,
    >> > and there can't be any phase drift. There should be no frequency
    >> > error (negligable would be more proper) with a divider, should there?
    >> >
    >> > All suggestions appreciated.
    >> >
    >> > Thanks,
    >> > Steve

    >>
    >> A 74HC390 will do, but you'll need a high speed comparator to obtain a good
    >> logic clock signal. Consider an NE529 or a MAX975. A circuit like this will
    >> have no drift but you may encounter jitter. This will mainly depend on the
    >> quality of your input signal but may be influenced by the comparator
    >> circuit.
    >>
    >> petrus bitbyter

    >
    >And if you're using a single supply comparator like the MAX975, you may
    >want to use the HP3325B auxillary Sync Output (square wave output, HI
    >>=1.2V, LO >= 0.2V), and be sure to terminate using a 50 ohm resistor. That square wave has great rise and fall times for your comparator conversion to TTL and then the HC390 (remember, /2 last if you want a 100KHz square wave).


    I haven't checked, but will the sync output vary when you change the
    phase on the 3325b? If it doesn't, then I don't need the circuit at
    all, and just can compare phase of the sync to the output. I'll have
    to check tomorrow.

    >
    >Don't worry, it's digital -- there will be _no_ frequency error from
    >the /100 section. Your propagation delays should be consistent too.
    >
    >Good luck
    >Chris
    sck0006, Mar 27, 2006
    #5
  6. sck0006

    sck0006 Guest

    <clip>

    > >And if you're using a single supply comparator like the MAX975, you may
    > >want to use the HP3325B auxillary Sync Output (square wave output, HI
    > >>=1.2V, LO >= 0.2V), and be sure to terminate using a 50 ohm resistor. That square wave has great rise and fall times for your comparator conversion to TTL and then the HC390 (remember, /2 last if you want a 100KHz square wave).

    >
    > I haven't checked, but will the sync output vary when you change the
    > phase on the 3325b? If it doesn't, then I don't need the circuit at
    > all, and just can compare phase of the sync to the output. I'll have
    > to check tomorrow.
    >

    Just checked today, the sync varies in phase w/ the output signal, so I
    can't use it for the reference phase. Thanks for the idea though. The
    reference signal is a 10MHz sine wave from an HP 58540A gps receiver,
    do you think this will be adequate to drive a comparator for a stable
    square wave out?

    Thanks for all your help everyone.

    Steve

    <clip>
    sck0006, Mar 27, 2006
    #6
  7. sck0006

    Chris Guest

    sck0006 wrote:
    > <clip>
    >
    > > >And if you're using a single supply comparator like the MAX975, you may
    > > >want to use the HP3325B auxillary Sync Output (square wave output, HI
    > > >>=1.2V, LO >= 0.2V), and be sure to terminate using a 50 ohm resistor. That square wave has great rise and fall times for your comparator conversion to TTL and then the HC390 (remember, /2 last if you want a 100KHz square wave).

    > >
    > > I haven't checked, but will the sync output vary when you change the
    > > phase on the 3325b? If it doesn't, then I don't need the circuit at
    > > all, and just can compare phase of the sync to the output. I'll have
    > > to check tomorrow.
    > >

    > Just checked today, the sync varies in phase w/ the output signal, so I
    > can't use it for the reference phase. Thanks for the idea though. The
    > reference signal is a 10MHz sine wave from an HP 58540A gps receiver,
    > do you think this will be adequate to drive a comparator for a stable
    > square wave out?
    >
    > Thanks for all your help everyone.
    >
    > Steve
    >
    > <clip>


    Hi, Steve. I'm not familiar with the HP58540A -- you might want to
    glance at the manual.

    Petrus' original idea is a good one. Just make sure you terminate the
    signal properly, and try it. If you get clean logic transistions at
    the comparator output, you should be done. If not, please feel free to
    post back.

    Good luck
    Chris
    Chris, Mar 27, 2006
    #7
  8. sck0006

    sck0006 Guest

    Chris wrote:
    <clip
    >
    > Hi, Steve. I'm not familiar with the HP58540A -- you might want to
    > glance at the manual.
    >
    > Petrus' original idea is a good one. Just make sure you terminate the
    > signal properly, and try it. If you get clean logic transistions at
    > the comparator output, you should be done. If not, please feel free to
    > post back.
    >
    > Good luck
    > Chris


    I'm having troubles. I want to use this whole circuit at a single +5V
    supply to simplify things. The only two comparators I have handy are
    an LM219D and an LM360. It appears (though I haven't actually
    experimented), that the LM360 won't run off that low a voltage on a
    single supply (the datasheet states minimum -4.5/+4.5). The LM219D
    seems to run fine off the single 5V, but I can't get good logic output
    above around 250-300kHz. At 10MHz, I can't get anything out besides
    either pegged at +5 or 0 w/ 10MHz noise (based on how I bias the
    comparator/input amplitude, etc...). Is this based on the fact that
    it's only rated for 80ns at +-15V, and that I'm using a sine wave
    input? Is there a better comparator that's readily avaliable in small
    quantities (<5), in a dip package, will run off of single +5V, and work
    well at 10MHz? The MAX975 looks nice, but I really don't want to get
    into surface mount parts. This is just a one time project I'm building
    on veraboard. I suppose I could implement a positive/negative supply,
    but I was just trying to keep it to minimum parts and maximum
    simplicity.

    Thanks for all your help, and I will clarify anything if necessary.

    Steve
    sck0006, Mar 28, 2006
    #8
  9. sck0006

    Chris Guest

    sck0006 wrote:
    >
    > I'm having troubles. I want to use this whole circuit at a single +5V
    > supply to simplify things. The only two comparators I have handy are
    > an LM219D and an LM360. It appears (though I haven't actually
    > experimented), that the LM360 won't run off that low a voltage on a
    > single supply (the datasheet states minimum -4.5/+4.5). The LM219D
    > seems to run fine off the single 5V, but I can't get good logic output
    > above around 250-300kHz. At 10MHz, I can't get anything out besides
    > either pegged at +5 or 0 w/ 10MHz noise (based on how I bias the
    > comparator/input amplitude, etc...). Is this based on the fact that
    > it's only rated for 80ns at +-15V, and that I'm using a sine wave
    > input? Is there a better comparator that's readily avaliable in small
    > quantities (<5), in a dip package, will run off of single +5V, and work
    > well at 10MHz? The MAX975 looks nice, but I really don't want to get
    > into surface mount parts. This is just a one time project I'm building
    > on veraboard. I suppose I could implement a positive/negative supply,
    > but I was just trying to keep it to minimum parts and maximum
    > simplicity.
    >
    > Thanks for all your help, and I will clarify anything if necessary.
    >
    > Steve


    Hi, Steve. Could you describe a little more about your situation?
    There are many ways to square up a 2-3VRMS sine wave into a stable
    digital logic signal, particularly if you're not too picky about 50%
    duty cycle.

    For one thing, it's fairly easy to do the level translation with a
    diode, transistor, and a couple of resistors if you have a low
    impedance signal source (view in fixed font or M$ Notepad):

    |
    | VCC
    | +
    | |
    | |
    | .-.
    | 1K| |
    | |
    | '-
    | |
    | o--------->
    | |
    | ___ |/
    | o------o->|-o-|___|-| 2N4401
    | | | 220 |>
    | 50 ohm| | |
    | .-. .-. |
    | | | | |220 |
    | | | | | |
    | '-' '-' |
    | | | |
    | | | |
    | o------o----o---------o
    | |
    | ===
    | GND
    |
    (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

    You may have to tweak the resistors a bit to be sure you get a good
    1-0-1-0 logic level here. This depends on the amplitude of your signal
    (you may need an additional gain stage if the level varies by a lot.
    Now if you had a veritable panoply of HC ICs available, you would then
    just use a 74HC14 to give you a squared off logic signal for your
    comparators. The 15ns propagation delay is sufficient for a 10MHz
    pulse.

    But actually, that probably isn't necessary. As long as your clock
    pulse width exceeds 30ns (check!), you should be OK. The HC390 is
    fairly forgiving on clock rise and fall times, at least on this time
    scale.

    Good luck
    Chris
    Chris, Mar 28, 2006
    #9
  10. sck0006

    Chris Guest

    Chris wrote:
    > |
    > | VCC
    > | +
    > | |
    > | |
    > | .-.
    > | 1K| |
    > | |
    > | '-
    > | |
    > | o--------->
    > | |
    > | ___ |/
    > | o------o->|-o-|___|-| 2N4401
    > | | | 220 |>
    > | 50 ohm| | |
    > | .-. .-. |
    > | | | | |220 |
    > | | | | | |
    > | '-' '-' |
    > | | | |
    > | | | |
    > | o------o----o---------o
    > | |
    > | ===
    > | GND
    > |
    > (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)


    Oh, yes -- diode 1N914 or equivalent signal diode -- don't use a 1N4001
    here.

    Chris
    Chris, Mar 28, 2006
    #10
  11. sck0006

    sck0006 Guest

    I'm probably getting confusing at this point. I'll try to clairfy. I
    have a 10MHz oscillator reference (the GPS receiver) feeding into a
    5087a distribution amplifier which is our main timebase for all the
    equipment. Therefore I can adjust the amplitude of the signal
    relitavely easily, but I would rather design the circuit to input a
    range of around 2-3VRMS, that way I can use any of the outputs from the
    amplifier because they are all adjusted within that range at this
    point, and we change around our equipment from different outputs often.
    I need to convert this 10MHz signal into a 100kHz signal. The shape
    of the 100kHz signal isn't necessarily important, as long as it is
    stable (no phase or frequency drift). That's pretty much it. I was
    going to use the HC390 for the divider, of course, and that part seems
    fine. I'm just working on the 10MHz TTL clock. That circuit you have
    looks promising. I had just input the sine directly into the
    comparator with the inverting input at a level of around 1VDC, and the
    sine wave of a level of appx 4VPK, (8VP-P). I'm not much of a design
    engineer, as you can tell, I mostly work on repair & cal of avionics.

    Thanks for all your help, I'll build up that circuit tonight and post
    back.

    Steve
    sck0006, Mar 28, 2006
    #11
  12. sck0006 wrote:
    > Chris wrote:
    > <clip
    > >
    > > Hi, Steve. I'm not familiar with the HP58540A -- you might want to
    > > glance at the manual.
    > >
    > > Petrus' original idea is a good one. Just make sure you terminate the
    > > signal properly, and try it. If you get clean logic transistions at
    > > the comparator output, you should be done. If not, please feel free to
    > > post back.
    > >
    > > Good luck
    > > Chris

    >
    > I'm having troubles. I want to use this whole circuit at a single +5V
    > supply to simplify things. The only two comparators I have handy are
    > an LM219D and an LM360. It appears (though I haven't actually
    > experimented), that the LM360 won't run off that low a voltage on a
    > single supply (the datasheet states minimum -4.5/+4.5). The LM219D
    > seems to run fine off the single 5V, but I can't get good logic output
    > above around 250-300kHz. At 10MHz, I can't get anything out besides
    > either pegged at +5 or 0 w/ 10MHz noise (based on how I bias the
    > comparator/input amplitude, etc...). Is this based on the fact that
    > it's only rated for 80ns at +-15V, and that I'm using a sine wave
    > input? Is there a better comparator that's readily avaliable in small
    > quantities (<5), in a dip package, will run off of single +5V, and work
    > well at 10MHz? The MAX975 looks nice, but I really don't want to get
    > into surface mount parts. This is just a one time project I'm building
    > on veraboard. I suppose I could implement a positive/negative supply,
    > but I was just trying to keep it to minimum parts and maximum
    > simplicity.
    >
    > Thanks for all your help, and I will clarify anything if necessary.
    >
    > Steve


    Use the Maxim parametric guide on the website to find a suitable device
    rated for single rail operation, and then order some free samples ;-)
    Start here: http://para.maxim-ic.com/index.mvp?tree=comparators&ln=en

    Dave :)
    David L. Jones, Mar 28, 2006
    #12
  13. sck0006

    John Fields Guest

    On 28 Mar 2006 11:08:42 -0800, "sck0006" <> wrote:

    >I'm probably getting confusing at this point. I'll try to clairfy. I
    >have a 10MHz oscillator reference (the GPS receiver) feeding into a
    >5087a distribution amplifier which is our main timebase for all the
    >equipment. Therefore I can adjust the amplitude of the signal
    >relitavely easily, but I would rather design the circuit to input a
    >range of around 2-3VRMS, that way I can use any of the outputs from the
    >amplifier because they are all adjusted within that range at this
    >point, and we change around our equipment from different outputs often.
    > I need to convert this 10MHz signal into a 100kHz signal. The shape
    >of the 100kHz signal isn't necessarily important, as long as it is
    >stable (no phase or frequency drift). That's pretty much it. I was
    >going to use the HC390 for the divider, of course, and that part seems
    >fine. I'm just working on the 10MHz TTL clock. That circuit you have
    >looks promising. I had just input the sine directly into the
    >comparator with the inverting input at a level of around 1VDC, and the
    >sine wave of a level of appx 4VPK, (8VP-P). I'm not much of a design
    >engineer, as you can tell, I mostly work on repair & cal of avionics.
    >
    >Thanks for all your help, I'll build up that circuit tonight and post
    >back.
    >
    >Steve


    ---
    From:

    http://groups.google.com/support/bin/answer.py?answer=12348&topic=250

    "Summarize what you're following up.

    When you click "Reply" under "show options" to follow up an existing
    article, Google Groups includes the full article in quotes, with the
    cursor at the top of the article. Tempting though it is to just
    start
    typing your message, please STOP and do two things first.
    Look at the quoted text and remove parts that are irrelevant.
    Then, go to the BOTTOM of the article and start typing there.
    Doing this makes it much easier for your readers to get through your
    post. They'll have a reminder of the relevant text before your
    comment, but won't have to re-read the entire article.
    And if your reply appears on a site before the original article
    does,
    they'll get the gist of what you're talking about."



    --
    John Fields
    Professional Circuit Designer
    John Fields, Mar 29, 2006
    #13
  14. sck0006

    sck0006 Guest

    On Tue, 28 Mar 2006 17:28:27 -0600, John Fields
    <> wrote:

    >On 28 Mar 2006 11:08:42 -0800, "sck0006" <> wrote:
    >
    >>I'm probably getting confusing at this point. I'll try to clairfy. I
    >>have a 10MHz oscillator reference (the GPS receiver) feeding into a
    >>5087a distribution amplifier which is our main timebase for all the
    >>equipment. Therefore I can adjust the amplitude of the signal
    >>relitavely easily, but I would rather design the circuit to input a
    >>range of around 2-3VRMS, that way I can use any of the outputs from the
    >>amplifier because they are all adjusted within that range at this
    >>point, and we change around our equipment from different outputs often.
    >> I need to convert this 10MHz signal into a 100kHz signal. The shape
    >>of the 100kHz signal isn't necessarily important, as long as it is
    >>stable (no phase or frequency drift). That's pretty much it. I was
    >>going to use the HC390 for the divider, of course, and that part seems
    >>fine. I'm just working on the 10MHz TTL clock. That circuit you have
    >>looks promising. I had just input the sine directly into the
    >>comparator with the inverting input at a level of around 1VDC, and the
    >>sine wave of a level of appx 4VPK, (8VP-P). I'm not much of a design
    >>engineer, as you can tell, I mostly work on repair & cal of avionics.
    >>
    >>Thanks for all your help, I'll build up that circuit tonight and post
    >>back.
    >>
    >>Steve

    >
    >---
    >From:
    >
    >http://groups.google.com/support/bin/answer.py?answer=12348&topic=250
    >
    >"Summarize what you're following up.
    >
    >When you click "Reply" under "show options" to follow up an existing
    >article, Google Groups includes the full article in quotes, with the
    >cursor at the top of the article. Tempting though it is to just
    >start
    >typing your message, please STOP and do two things first.
    >Look at the quoted text and remove parts that are irrelevant.
    >Then, go to the BOTTOM of the article and start typing there.
    >Doing this makes it much easier for your readers to get through your
    >post. They'll have a reminder of the relevant text before your
    >comment, but won't have to re-read the entire article.
    >And if your reply appears on a site before the original article
    >does,
    >they'll get the gist of what you're talking about."


    Sorry, I suppose I cut too much text out (all of it in this case,
    oops) and the original conversation was lost. Apologies to all for
    the confusion.

    Steve
    sck0006, Mar 29, 2006
    #14
  15. sck0006

    sck0006 Guest

    On 28 Mar 2006 14:44:58 -0800, "David L. Jones" <>
    wrote:

    >sck0006 wrote:
    >> Chris wrote:
    >> <clip
    >> >
    >> > Hi, Steve. I'm not familiar with the HP58540A -- you might want to
    >> > glance at the manual.
    >> >
    >> > Petrus' original idea is a good one. Just make sure you terminate the
    >> > signal properly, and try it. If you get clean logic transistions at
    >> > the comparator output, you should be done. If not, please feel free to
    >> > post back.
    >> >
    >> > Good luck
    >> > Chris

    >>
    >> I'm having troubles. I want to use this whole circuit at a single +5V
    >> supply to simplify things. The only two comparators I have handy are
    >> an LM219D and an LM360. It appears (though I haven't actually
    >> experimented), that the LM360 won't run off that low a voltage on a
    >> single supply (the datasheet states minimum -4.5/+4.5). The LM219D
    >> seems to run fine off the single 5V, but I can't get good logic output
    >> above around 250-300kHz. At 10MHz, I can't get anything out besides
    >> either pegged at +5 or 0 w/ 10MHz noise (based on how I bias the
    >> comparator/input amplitude, etc...). Is this based on the fact that
    >> it's only rated for 80ns at +-15V, and that I'm using a sine wave
    >> input? Is there a better comparator that's readily avaliable in small
    >> quantities (<5), in a dip package, will run off of single +5V, and work
    >> well at 10MHz? The MAX975 looks nice, but I really don't want to get
    >> into surface mount parts. This is just a one time project I'm building
    >> on veraboard. I suppose I could implement a positive/negative supply,
    >> but I was just trying to keep it to minimum parts and maximum
    >> simplicity.
    >>
    >> Thanks for all your help, and I will clarify anything if necessary.
    >>
    >> Steve

    >
    >Use the Maxim parametric guide on the website to find a suitable device
    >rated for single rail operation, and then order some free samples ;-)
    >Start here: http://para.maxim-ic.com/index.mvp?tree=comparators&ln=en
    >
    >Dave :)


    Good idea, I guess I'm just not too well versed at desigining circuits
    and selecting products. I'm more used to building pre-engineered
    circuits, but I really would like to expand my knowledge and
    experience. Thanks for the advice.

    Steve
    sck0006, Mar 29, 2006
    #15
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