Loading ...
Sorry, an error occurred while loading the content.

Re: [Electronics_101] LED Displays

Expand Messages
  • Gordon Tulloch
    Thanks for the advice guys - I ll check out the TIL-311. There s some on eBay for $6 a unit so I ll grab one and see if I can build a circuit around it. FYI
    Message 1 of 15 , May 31, 2004
    • 0 Attachment
      Thanks for the advice guys - I'll check out the TIL-311. There's some on
      eBay for $6 a unit so I'll grab one and see if I can build a circuit
      around it.

      FYI Dave the scope will be bartels driven with the Dave Ek encoder
      circuits - I'm leaning towards having the laptop send data to the
      display via the serial port...

      Thanks again!

      Regards,
      Gord

      JanRwl@... wrote:
      > Gord:
      >
      > The TIL-311 is a "neat" 7-segment (LED) readout with INCLUDED driver and
      > 4-bit latch. That is, you only need to feed it with BCD bits 0-3 (it
      > will also correctly display all-16 hexadecimal numerals, including
      > A,B,C,D,E, and F!
      >
      > When you go to the store to purchase these, take money!
      >
      > *Yahoo! Groups Sponsor*
      > ADVERTISEMENT
      > <http://rd.yahoo.com/SIG=1294s58ht/M=295196.4901138.6071305.3001176/D=groups/S=1706058037:HM/EXP=1086130476/A=2128215/R=0/SIG=10se96mf6/*http://companion.yahoo.com>
      >
      >
      > ------------------------------------------------------------------------
      > *Yahoo! Groups Links*
      >
      > * To visit your group on the web, go to:
      > http://groups.yahoo.com/group/Electronics_101/
      >
      > * To unsubscribe from this group, send an email to:
      > Electronics_101-unsubscribe@yahoogroups.com
      > <mailto:Electronics_101-unsubscribe@yahoogroups.com?subject=Unsubscribe>
      >
      > * Your use of Yahoo! Groups is subject to the Yahoo! Terms of
      > Service <http://docs.yahoo.com/info/terms/>.
      >
      >
    • Dave Mucha
      ... some on ... Very interesting program Mel has, microstepping in the hundreds and all that. I designed a large worm gear for a platform, but never got the
      Message 2 of 15 , Jun 1, 2004
      • 0 Attachment
        --- In Electronics_101@yahoogroups.com, Gordon Tulloch <gtulloch@s...>
        wrote:
        > Thanks for the advice guys - I'll check out the TIL-311. There's
        some on
        > eBay for $6 a unit so I'll grab one and see if I can build a circuit
        > around it.
        >
        > FYI Dave the scope will be bartels driven with the Dave Ek encoder
        > circuits - I'm leaning towards having the laptop send data to the
        > display via the serial port...
        >
        > Thanks again!
        >
        > Regards,
        > Gord

        Very interesting program Mel has, microstepping in the hundreds and
        all that.

        I designed a large worm gear for a platform, but never got the impetus
        to make the thing.


        Do you plan on putting your findings on a web site ?

        Will you announce it on scope-drive ?

        I am not an astromomer, but more in the CNC end of the mechanics and
        the boards.

        Also, do you run a dual voltage stepper for fast slews ? or how do you
        handle the speeds needed ?

        And, yes, this is E-101 related as the dual speed to which I spoke is
        a simple as a parallel port pin connected to an opto that in-turn
        drives a relay that then switches the voltage to the motor that spins
        the scope.

        Dave
      • mpdickens
        Speaking of gears and such, I ve been working on a project that uses the allegro a3967lsb microstepping driver. This driver is apparently the replacement for
        Message 3 of 15 , Jun 1, 2004
        • 0 Attachment
          Speaking of gears and such, I've been working on a
          project that uses the allegro a3967lsb microstepping
          driver. This driver is apparently the replacement for
          the ULN series of drivers from allegro (They state no
          new designs should be made with the ULN series and you
          should use the 3967). There is a lot of functionality
          built into the chip: It will do full, half, quarter
          and eighth steps.

          So far, it's been easy to impliment. However, there
          was a slight learning curve regarding the use of fast,
          slow and mixed decay modes and how these modes affect
          the behavior of the pwm current control.

          Regards

          Marvin Dickens

          =====
          Registered Linux User No. 80253
          If you use linux, get counted at:
          http://www.linuxcounter.org




          __________________________________
          Do you Yahoo!?
          Friends. Fun. Try the all-new Yahoo! Messenger.
          http://messenger.yahoo.com/
        • Paul Davis
          You might be able to use a pic. I ve successfully driven a four digit 1/4 LED display directly from the pic. Hooked up each segment s anode to a pin on one
          Message 4 of 15 , Jun 1, 2004
          • 0 Attachment
            You might be able to use a pic. I've successfully driven a four digit 1/4" LED display directly from the pic. Hooked up each segment's anode to a pin on one bus and then the common cathode of each digit to another port. I did not add a current limiting resistor as the pics current limit to about 25mA per pin. I then just did all the decoding and multiplexing in software. You could easily use the USART built into most pics to get serial data from the laptop or bit-bang it if you use a pic without a USART. I won't, however, promise you that it'll work forever as this setup may exceed the absolute maximum ratings of the pic. I have, however, not had a problem.

            Paul Davis


            On Mon, 31 May 2004 16:28:24 +0000, gordtulloch wrote:
            > Hi there:
            >
            >
            > I'm working on setting up the electronics for an automated
            > telescope project, and would like to have a display of the current
            > coordinates on the telescope itself rather than having to look at a
            > computer screen while trying to position the scope (plus I
            > eventually want to embed the computer in the scope with no other
            > display). Note that LEDs are preferred to LCDs since they freeze
            > pretty quick :)
            >
            > All of the encoders etc. are already taken care of, what I probably
            > need is some form of serially driven display module to mount on the
            > scope. Coordinate data that needs to be display is 2 displays of
            > three pairs of numbers each ie.
            >
            > 00 00 00
            > 00 00 00
            >
            >
            > Size of each number would be 1/2" or so. Can anyone refer me to a
            > kit or project that would fit the bill? Thanks!!
            >
            > Regards,
            > Gord
            >
            >
            > ------------------------ Yahoo! Groups Sponsor --------------------
            > ~--> Yahoo! Domains - Claim yours for only $14.70
            > http://us.click.yahoo.com/Z1wmxD/DREIAA/yQLSAA/1EGslB/TM -----------
            > ---------------------------------------------------------~->
            >
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
          • Steve
            ... digit 1/4 LED display directly from the pic. Hooked up each segment s anode to a pin on one bus and then the common cathode of each digit to another
            Message 5 of 15 , Jun 2, 2004
            • 0 Attachment
              --- In Electronics_101@yahoogroups.com, Paul Davis <paul_davis@s...>
              wrote:
              > You might be able to use a pic. I've successfully driven a four
              digit 1/4" LED display directly from the pic. Hooked up each
              segment's anode to a pin on one bus and then the common cathode of
              each digit to another port. I did not add a current limiting resistor
              as the pics current limit to about 25mA per pin. I then just did all
              the decoding and multiplexing in software. You could easily use the
              USART built into most pics to get serial data from the laptop or
              bit-bang it if you use a pic without a USART. I won't, however,
              promise you that it'll work forever as this setup may exceed the
              absolute maximum ratings of the pic. I have, however, not had a problem.
              >
              > Paul Davis
              >

              The PICs "current limit" is not meant to be used as a current limit,
              though. It is a max output rating. It's like flooring the gas at every
              light, and saying "don't worry, my car can only do about 140Km/hr
              before it shakes apart." Why risk the PIC and the project over four 3
              cent resistors?

              Since this -is- the Electronics_101 list, not Advanced-Electronics,
              I'll say that I think it's a bad idea to suggest to beginners that
              they take that particular short cut. What if a new variety of that PIC
              comes out that can put out more current?

              Alien Steve
            • Dave Mucha
              ... problem. ... PIC = $8.00 resistors = 4 cents lesson learned - priceless !
              Message 6 of 15 , Jun 2, 2004
              • 0 Attachment
                --- In Electronics_101@yahoogroups.com, "Steve" <alienrelics@y...> wrote:
                > --- In Electronics_101@yahoogroups.com, Paul Davis <paul_davis@s...>
                > wrote:
                > > You might be able to use a pic. I've successfully driven a four
                > digit 1/4" LED display directly from the pic. Hooked up each
                > segment's anode to a pin on one bus and then the common cathode of
                > each digit to another port. I did not add a current limiting resistor
                > as the pics current limit to about 25mA per pin. I then just did all
                > the decoding and multiplexing in software. You could easily use the
                > USART built into most pics to get serial data from the laptop or
                > bit-bang it if you use a pic without a USART. I won't, however,
                > promise you that it'll work forever as this setup may exceed the
                > absolute maximum ratings of the pic. I have, however, not had a
                problem.
                > >
                > > Paul Davis
                > >
                >
                > The PICs "current limit" is not meant to be used as a current limit,
                > though. It is a max output rating. It's like flooring the gas at every
                > light, and saying "don't worry, my car can only do about 140Km/hr
                > before it shakes apart." Why risk the PIC and the project over four 3
                > cent resistors?
                >
                > Since this -is- the Electronics_101 list, not Advanced-Electronics,
                > I'll say that I think it's a bad idea to suggest to beginners that
                > they take that particular short cut. What if a new variety of that PIC
                > comes out that can put out more current?
                >
                > Alien Steve


                PIC = $8.00
                resistors = 4 cents
                lesson learned - priceless !
              • Stefan Trethan
                ... i basically agree, and i would use resistors. however, a teacher of mine used a diode in series with 8 leds (one diode for all leds, in the common ground
                Message 7 of 15 , Jun 2, 2004
                • 0 Attachment
                  >
                  > PIC = $8.00
                  > resistors = 4 cents
                  > lesson learned - priceless !


                  i basically agree, and i would use resistors.
                  however, a teacher of mine used a diode in series with 8 leds (one diode
                  for all leds, in the common ground connection) on the output port of a
                  micro
                  for years. this was a system meant for education, and hundreds were built
                  and used
                  over the years. there was not a single problem with that setup as far as i
                  know.

                  What i want to say is if you know what you are doing, and carefully test
                  things
                  you can cut corners. the forward voltage of diode and led was enough to
                  limit the current,
                  through the inner reistance of the port output.

                  use resistors ;-)

                  st
                • Paul Davis
                  Will if you really want to make sure you don t exceed maximum ratings you d have to use fets on the segment commons as it has to sink the current from 7
                  Message 8 of 15 , Jun 2, 2004
                  • 0 Attachment
                    Will if you really want to make sure you don't exceed maximum ratings you'd have to use fets on the segment commons as it has to sink the current from 7 segments so you could only do 3.5mA/segment if you limit to 25mA. Since you also have each digit on for only 1/4 of the time the effective current is less than a milliamp which is probably going to result in a display which is far too dim.

                    Paul Davis

                    On Wed, 02 Jun 2004 19:07:35 +0000, Steve wrote:
                    > --- In Electronics_101@yahoogroups.com, Paul Davis
                    > <paul_davis@s...> wrote:
                    >
                    >> You might be able to use a pic. I've successfully driven a four
                    >>
                    > digit 1/4" LED display directly from the pic. Hooked up each
                    > segment's anode to a pin on one bus and then the common cathode of
                    > each digit to another port. I did not add a current limiting
                    > resistor as the pics current limit to about 25mA per pin. I then
                    > just did all the decoding and multiplexing in software. You could
                    > easily use the USART built into most pics to get serial data from
                    > the laptop or bit-bang it if you use a pic without a USART. I
                    > won't, however, promise you that it'll work forever as this setup
                    > may exceed the absolute maximum ratings of the pic. I have,
                    > however, not had a problem.
                    >
                    >>
                    >> Paul Davis
                    >>
                    >
                    > The PICs "current limit" is not meant to be used as a current
                    > limit, though. It is a max output rating. It's like flooring the
                    > gas at every light, and saying "don't worry, my car can only do
                    > about 140Km/hr before it shakes apart." Why risk the PIC and the
                    > project over four 3 cent resistors?
                    >
                    > Since this -is- the Electronics_101 list, not Advanced-Electronics,
                    > I'll say that I think it's a bad idea to suggest to beginners that
                    > they take that particular short cut. What if a new variety of that
                    > PIC comes out that can put out more current?
                    >
                    > Alien Steve
                    >
                  Your message has been successfully submitted and would be delivered to recipients shortly.