Help on using Hitachi V-212 Oscilloscope

Thread Starter

DrCowiber

Joined Jul 15, 2021
16
You may not appreciate it at this point but your oscilloscope will be your #1 diagnostic tool right next to the DMM.

First step is to read the User Manual.
https://dcfa.exa.unicen.edu.ar/wp-content/uploads/sites/18/2019/02/Osciloscopio_hitachi_v-212.pdf

Second step is to become familiar with each control on the front panel. We will guide you with this.
Hello,

The booklet XYZ of oscilloscopes will give you hints on how to use an oscilloscope.

Bertus
thanks, I will go through these
 

MrChips

Joined Oct 2, 2009
24,134
1627239308780.png

There are three main sections of the oscilloscope:

1 - Vertical Amplifiers
2 - Horizontal Time Base
3 - Trigger Control

Let us take one section at a time.
1 - Vertical Amplifiers

These are your signal input channels, CH1 and CH2.
Set AC-GND-DC toggle switch to both channels to GND. We will discuss this in a minute.
Set MODE to ALT.
You should see two horizontal traces on your screen.
Adjust POSITION on each channel to move the traces up and down.
 

MrChips

Joined Oct 2, 2009
24,134
Leave the TIME/DIV control to 1ms for now.

1 - Vertical Amplifiers

Let us discuss the input BNC jack now.

CH1 and CH2 inputs are 1MΩ impedance with 25pF parallel capacitance. This is typical for oscilloscopes.
This means that when your input of the 'scope is connected to a circuit under test it will load your circuit with the equivalent of a 1MΩ resistor and a 25pF capacitor in parallel. This may or may not create a problem. In general we want the load impedance to be as large as possible.

That is the function of a x10 oscilloscope probe. Check your probe and see if it is x1 or x10. Some probes have a switch selectable x1 and x10 function. Let us know what you have and we will discuss this in more detail.

VOLTS/DIV

There is a red rotary knob on CH1 and CH2 controls.
Pull is knob out for x5 gain. Normally you will use this knob pressed in for x1 gain.
Turn the knob fully clockwise to the CAL position. These two settings are your usual settings.

Turn the VOLTS/DIV knob fully counter clockwise to 5V.
This means that your 'scope scale is now calibrated at 5V per division.
A span of four division (half the screen height) would reflect 20V input signal with a x1 probe.

Adjust the CH1 position to bring the horizontal trace to the mid-screen (scale with the fine tick marks).
 
The x10 scope probe will bring the input Z up to 10 meg-ohms.

Probe compensation and what it is will be discussed later, after you get a trace and then a trace using the calibrator output.
 

Thread Starter

DrCowiber

Joined Jul 15, 2021
16
Leave the TIME/DIV control to 1ms for now.

1 - Vertical Amplifiers

Let us discuss the input BNC jack now.

CH1 and CH2 inputs are 1MΩ impedance with 25pF parallel capacitance. This is typical for oscilloscopes.
This means that when your input of the 'scope is connected to a circuit under test it will load your circuit with the equivalent of a 1MΩ resistor and a 25pF capacitor in parallel. This may or may not create a problem. In general we want the load impedance to be as large as possible.

That is the function of a x10 oscilloscope probe. Check your probe and see if it is x1 or x10. Some probes have a switch selectable x1 and x10 function. Let us know what you have and we will discuss this in more detail.

VOLTS/DIV

There is a red rotary knob on CH1 and CH2 controls.
Pull is knob out for x5 gain. Normally you will use this knob pressed in for x1 gain.
Turn the knob fully clockwise to the CAL position. These two settings are your usual settings.

Turn the VOLTS/DIV knob fully counter clockwise to 5V.
This means that your 'scope scale is now calibrated at 5V per division.
A span of four division (half the screen height) would reflect 20V input signal with a x1 probe.

Adjust the CH1 position to bring the horizontal trace to the mid-screen (scale with the fine tick marks).
I have my line in the middle with the knobs where you specified. The probe I have is switchable between x1 and x10. it is set to x1 right now.
 

MrChips

Joined Oct 2, 2009
24,134
1 - Vertical Amplifiers

Oscilloscope Probes


The basic oscilloscope has an input impedance of 1MΩ.
It is desirable to have the least effect on the circuit being tested by having the highest 'scope impedance possible. Many DMM have impedance of 10MΩ when set to measure voltage.

It is generally a good habit to use an oscilloscope probe with x10 attenuation.
This has three effects.

1) It increases the input impedance to 10MΩ.
2) It extends the bandwidth of oscilloscope + probe system.
3) It attenuates the input signal by a factor of 10, in other words, it increases the voltage measurement range by a factor of 10. The VOLT/DIV scale is now changed by a factor of 10.

Set the oscilloscope probe to the x10 attenuation setting and leave it in that setting.
Mentally make a note of this and multiply the VOLT/DIV control knob by 10, e.g. 5V becomes 50V.
.2V becomes 2V.

Note: It is important that you adjust the frequency compensation trimmer capacitor found on the oscilloscope probe.
Before we can do this, let us complete the overview of the rest of the oscilloscope.
 

MrChips

Joined Oct 2, 2009
24,134
AC - GND - DC

This can be a bit confusing to newcomers.

The GND setting is easy. This is used to establish a 0V reference on the screen. Setting the toggle switch to GND does not ground the circuit being tested. It only affects the internal measurement within the oscilloscope.

You should get into the habit of always selecting the GND option and adjusting the CH1 horizontal line to the middle of the screen. In this manner, positive voltages are above the center line and negative voltages are below the center line.

For CH2, sometimes you may want to set the 0V reference on the center line when comparing CH1 and CH2 voltages. This will likely confuse you or obscure one of the lines. When you wish to compare two signals in time it may be preferable to offset CH2 0V reference to be below or above the center grid line. This is a user preference.

Someone may think that DC setting is for measuring DC signals and AC is for measuring AC signals. No so.
All signals can be considered to contain both DC and AC. For example, you may have a 1mV AC ripple superimposed on top of a 5V DC signal.

When you need to measure the absolute amplitude of a waveform, use DC option.
With a x10 probe, a 5VDC signal will appear 2½ divisions above 0V reference when VOLT/DIV is set to .2V.
If you attempt to view the 1mV AC ripple by setting VOLT/DIV to a lower setting you will move the trace beyond the top of the screen.

In order to view the AC ripple, select the AC option. This introduces a high-pass filter into the input of the amplifier and thus removes the DC component of the signal. In other words, the effect is the average value of the signal is shifted to appear about the 0V reference line on the screen grid. Now you can reduce the VOLT/DIV setting to a lower value.

You may continue to use the scope in the DC setting even when examining an AC signal. In this case you will be able to see the true voltages present in the signal, DC and AC.

In summary, DC setting is used to observe DC and AC.
AC setting is used to remove any DC offset.

CAUTION with using ground clip
While we are discussing ground, a word of caution is imperative.
Your oscilloscope is wired to the ground pin on your AC mains supply. This is directly connected to the ground clip on the oscilloscope probe. You may use the probe without connecting the ground clip in many situations. The ground clip is needed when measuring high frequency signals or when you want the best possible measurement free of noise and artifacts. Note the following:

1) If the circuit under test is not connected to ground or any reference, connect the ground clip to a common node in the circuit.

2) If the circuit under test is already connected to ground you can either not use the ground clip at all or connect the ground clip to a point in the circuit that you are certain is ground. Failure to confirm a correct ground node could result in damage to the circuit under test and/or the oscilloscope.

Ground isolation is another topic which we will leave for another time.
 
As Mr Chips said, be careful with the ground potential. Generally, don't use the ground clip. There is a ground binding post where you can ground an isolated circuit.

Where the ground can bite you big time is working on the mains side of a switching power supply.

Note on channel B, there is a "pull to invert" position?
This allows you to make a pseudo-differential measurement. You get A-B, BUT you must have a ground reference.

So it's more like (A-GND)-(B-GND)=A-B
 
Mode:
Cha1 - just channel 1
Cha2 - just channel 2
Alt - Sweeps A, then B
Chop - It does a piece of each channel alternately
Add - Adds two channels. When B is inverted A-B

ALT and CHOP depend on the frequencies involved.
 

Thread Starter

DrCowiber

Joined Jul 15, 2021
16
Mode:
Cha1 - just channel 1
Cha2 - just channel 2
Alt - Sweeps A, then B
Chop - It does a piece of each channel alternately
Add - Adds two channels. When B is inverted A-B

ALT and CHOP depend on the frequencies involved.
thanks for explaining these, I did not understand what chop and add meant at all.
 

MrChips

Joined Oct 2, 2009
24,134
Before moving on to the remaining two sections of the oscilloscope, let us finish off with the MODE settings.

CH1 - display trace on CH1 input only. Make sure INT TRIG is set to CH1 (or set to a channel with a valid signal)
CH2 - display trace on CH2 input only. Make sure INT TRIG is set to CH2 (or set to a channel with a valid signal)
ALT - the scope will sweep with CH1 on one valid trigger followed by a sweep of CH2 on the next valid trigger
CHOP - the trace will be time shared (chopped as it moves across the screen) between CH1 and CH2. This is useful at lower frequencies when you want to simultaneously view both channels
ADD - show the arithmetic addition of CH1 + CH2 on a single trace. If CH2 INVERT is invoked then it becomes CH1 - CH2.

INT TRIG (Internal Trigger)
CH1 - trigger the scope only on CH1 input signal even when viewing CH1 and CH2
CH2 - trigger the scope only on CH2 input signal even when viewing CH1 and CH2
VERT MODE - trigger the scope on CH1 and display CH1, followed by CH2 display on CH2 trigger while in ALT mode. This is used when CH1 and CH2 signals are of different frequencies and/or not synchronized.

NOTE: This is a single beam oscilloscope. It can only display one channel at a time.
In order to appear as if there are two traces, i.e. in order to display two channels simultaneously the beam is shared between the two channels. This is accomplished by either
1) ALT - alternate sweeps, where one sweep shows CH1 and the next sweep shows CH2
2) CHOP - the trace is rapidly switched between displaying each channel as the trace moves from left to right across the screen.
 
See if you can get a trace with the probe connected to the CAL pin on the face of the scope. Your on your own. The trace could drift. Don't worry about it yet. More knobs to twiddle.
==
You have a dual trace scope and not a dual trace, dual time-base scope which can be more complicated.
 
Last edited:

MrChips

Joined Oct 2, 2009
24,134
Moving on, you will notice that the red knobs have dual functions. Press the knobs in. Rotate fully clockwise for normal usage.

2 - Horizontal Time Base

TIME/DIV


This is the easy one. This controls how quickly the electron beam moves across the horizontal axis (X-axis).
The numbers are straight forward. There are 10 divisions across the screen. At a setting of 1ms it takes 10ms to traverse across the screen. A 1kHz square wave would show a full cycle at every division interval.

Set the TIME/DIV at longer times to view low frequency signals. Set to shorter times to view high frequency signals.

Set TIME/DIV to 1kHz.
Connect CH1 probe to the CAL .5V square wave test output.
Set MODE to CH1
INT TRIG to CH1
AC-GND-DC to DC

Experiment with VOLT/DIV and TIME/DIV settings.
Ignore X-Y option for now.

If you are having difficulties seeing a stable waveform, wait for the next post.
 
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