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8 TRACES ON A SINGLE CHANNEL CRO

simon christoforidis
Prodigy 200 points

Hello from Sydney Australia!

I have tried a circuit that 'Ramps' eight traces on a single channel CRO.

I have tested it and it 'Strobes' 4 traces quite well but 8 traces looks to be a little harder.

Without trial and error ,in theory how do you work out the Clock Frequency needed to display the

full 8 traces at about 10-25 frames per second without noticeable 'flicker'?

It is a Digital Cro , and therefore the need for a variable Clock as the Digital Cro's don't seem to

have a Variable Time Base.

In order to continue pursuing this circuit the Display part of the circuit has to work first.

If it is 'Out of Sync' with the 'Test Circuit' a 'Memory Buffer' will sort out this problem , even if it doesn't

display it in 'Real Time'.

Thankyou-Simon

  • 0
    TI__Mastermind 24205 points

    Hi Simon,

    We do not have a good understanding of your system to be able to recommend a clocking solution. Have you tried looking on our website http://www.ti.com/lsds/ti/analog/clocksandtimers/clocks_and_timers.page to see if you can find any device that will meet your needs?

    Regards

    Arvind Sridhar

  • 0 in reply to Arvind Sridhar
    Prodigy 200 points

    Hello.I've made asynchronous Memory Buffer to display the 8 traces at it's own time.

    The Oscilloscope (Digital) has 'Persitance' in 1,2,5 seconds and 'infinite' which should help , although the signal Is

    quite 'noisy' and has to be improved to be worthwile.The 'strobing' has two problems;

    *1 If I trigger on each of the traces , the traces are good , but it doesn't  'syncronise' with the start (First Trace).

    *2 If I trigger on the First Trace , the display won't 'Reset' with each trace and therefore the display appears 'stepped'.

    Maybe if I start the circuit and reset the 'First Trace' with the 'First Frame' the circuit should remain in 'Sync' and

    then all I have to do is worry how the Oscilloscope Screen is Syncronised.-I'm still working on it.

    The Multiplexer is a simple circuit with the heart of the circuit being a 4051B.It is a 8 bit to 1 +/-7.5Volt with

    binary inputs to select the trace.I'm switching the traces at less than 1Mhz which should be more than fast

    enough.As mentioned before the output is quite noisy and that is probably the only drawback as I don't really

    mind if the display is 'asynconous' and only want to use the display as it is cheaper than using LEDS.

    With 'Persistance' it makes a ideal display for many circuits -but the noise and the fact that I made it on 'Vero-

    Board'-Strip Board, probably makes the noise worse

    I'll send a 'Screen Shot' in the near future of the Output Signal.

    Thankyou

    Simon Christo

    27/01/14