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Thread: User manual for Telequipment D54 oscope?

  1. #1
    Registered slp_prlzys's Avatar
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    User manual for Telequipment D54 oscope?

    I got me a vintage oscilloscope
    it seems alive, but I have no idea
    how to use one, so I'm not sure if
    it's really functional. I just thought
    it would be fun to learn how to
    use one

    TIA
    Mhel®

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    mhel
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    slp_prlzys:

    For the most part you probably do not need a manual for an ordinary conventional cathode-ray oscilloscope. Usually a 5" round face, masked to a rectangular area.

    Basically this is a three axis device, X, Y, Z. Where X is horizontal and most often used as a linear time base; Y is vertical (maybe more than one channel) and is the usual signal channel; and Z is the beam intensity. Z in an oscilloscope is not often used other than as a fixed level, or in some cases to identify a certain time region.

    When X is used as a time base, the usual case, it is usually generated internally by a saw tooth generator with adjustable rates and sync capability. This might range from 5 sec/cm to 0.1 microsec/cm. Sync may be selectable internally from one of the Y channels, or internally from line frequency, or external. In some scopes (Tektronix) since the 40's there has existed the ability to select slope (neg or positive ), and amplitude. Also AC or DC coupling.

    Both X and Y external usually have DC or AC coupling available. Range switches are usually in a 1, 2, 5 sequence.

    There will be an intensity and a focus control.

    If the X axis ( horizontal ) is switched to external, then you can do an X Y plot of one voltage vs another. In this mode if you plot one sine wave vs another you can genetrate Lissajous figures. For limited discussion see p 467 of "Basic Electrical Measurements" by Melville B. Stout, University of Michigan, 1950, Prentice-Hall. This is a good book for a study of bridge circuits. Two sine waves of the same frequency and phase produce a straight line at an angle. With one at 90 deg phase shift you get an ellipse. If deflection sensitivity is the same in both X and Y, then 90 deg produces a circle. Other phase angles can be estimated from the angle of the ellipse. Integral related frequencies produce interesting curves.

    Keep the intensity at a minimum for your purpose to avoid burning the screen.

    Experiment and find out what you can do.

    .



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    slp_prlzys:

    Some ways to get signals to play with.

    Lissajous:

    1. Use a 6 to 24 v filament transformer to feed the external input to the X (horizontal axis). On most scopes the X-axis has limited voltage ranges, and adjustment, if any. Feed this same signal to the Y-axis and you get a straight line. Adjust Y-axis gain as desired.

    2. Put a 1 microfarad capacitor across the Y input, not electrolytic. In other words paper, Mylar, oil, or ceramic. If I calculated correctly about 2700 ohms will produce a 45 deg phase shift. Put 2700 ohms from your X input to the Y input and adjust Y gain, an ellipse appears. If the resistance becomes close to infinite, then the phase shift is close to 90 deg, but the signal is near zero. To get 90 deg or approaching 180 deg use two RC circuits cascaded. Three will allow 180 deg with a reasonable signal output.

    This three stage RC phase shift circuit is what created the HP company. HP used a ganged air variable condenser, like those in radios, and switch slectable resistors for frequency adjustment. Also unique was use of a tungsten incandescent lamp as part of the feedback path for automatic gain adjustment. These oscillators produced relatively constant amplitude over frequency.

    3. Continue with the fixed frequency sine wave to the X input and conect a varaible frequency oscillator, such as the HP 200CD, to the Y input. Now you can produce Lissajous figures of different frequencies and phases.


    Other Waveforms:

    4. Now change to time base on X and play with different time bases, synchronization, and Y sine wave inputs of different frequencies from the oscillator. There are also function generators that produce different waveforms.

    5. Generate a sawtooth wavform with an NE55 neon bulb, a capacitor across the neon bulb, a resistor from neon bulb to a 100 to 170 v source. I have not experimented with this in a long time, but try 100,000 ohms and 0.1 microfarad.

    The time constant is T = R * C where T is in seconds for R in megohms and C in microfarads. Depending upon the source voltage you will be less than one time constant for the frequency of oscillation. The capacitor voltage rating should be 200 v or more. An electrolytic is ok if polarized correctly. There is never a reversal of voltage on the capacitor in this circuit.

    The neon bulb has the characteristic that the breakdown voltage is higher than the glow discharge voltage. The bulb is a high resiatance until it breaks down, then the voltage drops to about 50 v for the glow discharge voltage drop. I do not remember the breakdown voltage, but it is probably 70 to 90 volts. Never apply a voltage greater than the breakdown voltage to a gas discharge device without current limiting. Flourscent lamps as well as neon lamps.

    Maybe use 100 ohms in series with the neon bulb to limit peak discharge current from large capacitors.

    6. Use a NE555 timer chip to produce rectangular and sawtooth waveforms.

    7. A microphone and audio amplifier and look at your voice waveform or other signals like a tuning fork. Note tuning forks are very close to a high-Q damped sinusoidal waveform.

    .



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    That's a lot to digest.
    There's just too many knobs in it,
    the only knob that I'm sure is working
    is the position there seems to be a
    dot at one side of the screen and
    it moves up/down with that knob.
    does CM means centimeter? I'm used
    to seeing it in lowercase cm, I can't
    figure out what Volts/CM means.
    I guess the focus would be the intensity
    adjusment. Trig would be trigger( I think
    I read it somewhere) and there's the selector
    for the trigger.
    It didn't came with a probe, I guess
    there's no way I could do some experiment.
    (I won one from ebay HP-9060 for $10, waiting for now)

    I think the simplest experiment would be the #2 of the Lissajous
    (how's it pronounce anyway).
    I hope it's functional or it will be a huge enclosure for
    a PSU.

    thanks

    Attached Thumbnails Attached Thumbnails -d54-jpg  
    mhel
    "This is intentionally left blank."


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    Community Moderator Al_The_Man's Avatar
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    If your new to 'scopes, realize that what they are primarily for is to see wave forms etc that you cannot otherwise see on instruments like VOM's etc because of the fast changing nature of the waveform, try looking at simple things at first to get an idea, for example if you have a power supply, look at the secondary ac waveform and the rectified supply to see how the DC is processed rectified and smoothed.
    And measure the amplitude (Y) and also see the effect using the AC & DC switch, in the AC position the DC will be removed from the display, such as when the degree of ripple is required to be seen on a smoothing capacitor, if the switch is in the DC position the AC ripple will be seen riding on top of DC waveform.
    One precaution to observe is that the probe ground connection is usually at power ground potential and if using the 'scope on non-isolated equipment, can cause dramatic effects, as well as personal danger.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design (Skype Avail).

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    "One precaution to observe is that the probe ground connection is usually at power ground potential and if using the 'scope on non-isolated equipment, can cause dramatic effects, as well as personal danger."

    Thanks for the tip.
    I realize oscopes are use
    to look at waveforms.Actually when
    I got this thing the first thing I took was
    wallwart transformer in use by the telephone
    so I could view sinewave, but not knowing
    what knobs to turn the fun just fades slowly.

    mhel
    "This is intentionally left blank."


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    slp_prlzys:

    The fact that you have only a single spot means that there is no signal to the X axis, as well as none to the Y.

    Intensity and focus are two different things. Both affect the beam. Intensity controls the electron beam current level, and therefore brightness. Focus adjusts spot size. The independent effects will become more apparent when you get a horizontal sweep signal.

    Do not let the spot stay in one place very long.

    Probably the first thing to do is apply a vertical signal and at least get the spot to create a vertical line, if possible.

    To find out how to pronounce Lissajous go to www.dictionary.com then enter the word. You can also produce Lissajous patterns with a compund pendulum.

    A wall transformer cube in many cases includes a rectifier and filter capacitor. Look for one that is only an ac output.

    There should be two positioning controls, one vertical and one horizontal. See if these will move the spot around. If you can only get a spot it would be best to defocus it, and keep the intensity low.

    If the positioning controls work, then the above vertical axis signal test will tell you whether the amplifier is working. Positioning also probably comes thru the amplifier.

    Your scope is almost certainly electrostatic deflection. If no amplifiers worked and there was was no unbalance voltage on the deflection plates, then the spot should be near the center of the screen.

    If the vertical amplifier appears to work, then play with the controls for the horizontal. Set the horizontal sweep selector to Amplifier if such a position exists, or some other switch that might perform this function. Apply an external signal and see if you get horizontal deflection.

    .



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    Tektronics.com has some useful PDF's including 'the xyz of oscilloscopes' at ; http://www.tek.com/Measurement/cgi-b...opes_education

    look towards the bottom of the page....



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    slp_prlzys:

    I have printed a portion of your front panel photo.

    Brillance is intensity, focus is focus. Scale illumination controls the side lighting on the screen scale.

    Yes CM or cm is centimeters.

    You have two Y axis channels with independent adjustments. You have DC GND and AC. GND shorts the input. You can choose whether either or both channels are on. If both are on, then you need to select Chop or Alternate.

    On the right side is your time base generator and selection of external X. I can not read most of the pushbuttons. Set the time base switch to 2 ms/cm. Adjust stability to see if you can get a sweep. If there is a selection for line sync then select this.

    If the sweep oscillator won't work, then set time base selector to external and put a signal between GND and EXT X as I previously described.

    .



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    Thanks for the help, I manage to show
    me some wave YEEESSSS!
    both channels seems to be working.
    I only get signal when I press the HF button
    from the trigger selector(could be the line thingy)
    The horizontal position knob wasn't too obvious
    to me, 'cause it's not close to the vertical pos knob.
    Focus knob works, so is the trace rotation I can't
    see any effect of the brilliance knob, it's not easy
    to the eyes this greenish light that flashes across
    the screen . Timebase knob works, I don't see
    any effect of stability knob nor trig level.
    So far I'm glad that it works, now I need to
    realy learn how to use it, not 'till I actually
    have a need for it, but I'll try those experiment
    you posted it should be fun.

    gar: thanks again

    Attached Thumbnails Attached Thumbnails -acwave-jpg  
    mhel
    "This is intentionally left blank."


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    slp_prlzys:

    Can you mount the camera on a tripod and zoom to cover only the horizontasl sweep area of the front panel and shoot without flash. Then we might be able to read the details.

    HF may stand for high frequency reject, mean it uses a low pass filter at the trigger input.

    Horizontal width should be across the entire screen. With no vertical input you should be able to get a continuous horizontal scan line. You do not want to be in single trigger mode, if one exists on your scope. At the 2 ms/cm sweep rate I suggested you will get 20 ms across the screen. 1/60 second is 16 milliseconds.

    In non-single-shot mode the horizontial scan should continuously repeat. Thus, at the 2 ms/cm rate you would have a bright horizontal line with no flicker.

    .



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    Red face I got smoked!!

    gar:
    I played with it once more so
    I could get closeup view(no tripod tho).
    I found out it wasn't the HF button that makes
    the signal visible it was the Stability knob.
    If I got the knob turn fully CCW the dot disappear
    (BTW the only way I was able to see a dot before
    was when I had TIME knob set to EXT X).

    The xsweep.jpg was obtain following your instruction.
    I think I'm starting to get it, there are 10 squares in
    the horizontal grid setting the TIME to 2ms does makes
    makes the beam sweep 20ms accross( i actually measure
    the squares and it's 1 cm² and set the TIME to .5 sec
    ans see how long it takes to cross the screen, seems right),
    but it flickers tho, playing with the VARIABLE knob of
    TIME knob makes it a little bit stable but still flicker,
    with 1ms no flicker.

    The wave.jpg obtain using an 19Vac walwart transformer
    with an improvised probe that is. VOLT/CM set as 10V
    TIME set as 2ms. I took it after I got the smoke.
    After I took the first picture(xsweep) I unplug the oscope,
    then I decided to clean the screen, I found out that
    there's a green filter (not a monochrome green as I
    originally thought)in between the scale and the crt. I put
    everything back the way they are (I think). Fired it up
    again probed the transformer I got the wave, I was
    go'nna take picture of it when I notice it's dark so I
    turn the SCALE ILLUM knob nothing seems to be happening
    then I saw the smoke comin' out of the right side of
    the enclosure, I panicked and quickly turned it off ,
    tried opening it if there's any visible burnt nothing obvious.
    I fired it up again no smoke except for the Illumination
    of the scale everythings seems to be ok. Should I be worried?
    That' how I got the wave picture. Whew!!
    There's another pic I attached. how are trigger used?

    thanks

    Attached Thumbnails Attached Thumbnails -xsweep-jpg   -wave-jpg   -d54x-jpg  
    mhel
    "This is intentionally left blank."


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