Test Equipment: Oscillocopes

[John.K1]

Thanks TK, guys .

Very educational this thread.
I have no much electro experience, so measuring principles are a pain in an ars for me. Some tutorial like yours TK are very helpful. There is not many of such on YouTube.
Tell me please, is there situation when you measure just with one probe-end connected- no ground connected and what does it actually show that way? I know when I connect some coil just on main probe-no ground, it shows me around 50-60Vpp amplitudes of whatever it catch from the air.
If I good understand , the correct measurement are performed if you exactly match the impedance of the probe/scope?  Would that my de-coupling 1pf cap work here in this case- ?  I guess it would as the ringing is the mater of the capacitance of the wire.

TK- just thinking to get this probe. What is your opinion?  http://www.ebay.com/itm/High-Voltage-5KV-5000V-300MHz-Oscilloscope-Scope-Passive-Clip-Probe-100X-P2300C/281598591049?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20131003132420%26meid%3Dfbc3c9e6d2d743809e66c027e2f7b290%26pid%3D100005%26rk%3D5%26rkt%3D6%26sd%3D301521247426&rt=nc  -this is what I do not understand- can my scope + this 5KV probe (100x)  withstand that 5KV voltage, or does my oscilloscope must also support some more higher voltage?

Thanks

[kEhYo77]

Good topic!
As for SG on the 'cheap' I have recently bought this type of DDS generator.
Very capable, small, handy and very affordable!

This is a complete DDS signal source, Adopts DC5V power supply, can output the sine wave, square wave
(Duty cycle Can be adjust from1% -99%) , triangle wave and sawtooth wave and various function wavefrom,
maximum output can reach up to 10 Vpp, frequency range from 0.01 Hz-5 MHz .
Resolution for 10 MHz, with TTL synchronization output and 60 MHz frequency meter.

[John.K1]

This is SG I use http://www.ebay.ie/itm/321157000855?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649. I am very happy with it.

I am also isolating it through the opto-couple.

[TinselKoala]

This is the kind of thing that scares me about scopes.  This is why I wanted to get a simple fg to produce known traces on the scope so I could see what they are supposed to look like.  I have learned here that most of the time, you use the 10x settings on the probes.  This is good info but...do we use that in our calculation of voltage and current when reading the traces?

In other words....I am on 1 volt/div. and the trace shows a peak of 3 divs.  I am on 10x probe setting.  Does this mean I am seeing 3 volts?  30 volts?  Or
.3 volts?  My scope (tek 2213) has the manual pouch bolted to the top of the case, which I did not like at first however, the manual did survive with the unit from the 80's so...it was a good idea.  I have read this many times but there are some simple things I can not figure out...the probe setting being one of them.

Bill, doesn't your 2213 have the same kind of vertical range knobs and markings as the 2213a? The markings should be self-explanatory... if you use a 10x probe you read the value under the "10x probe" marking and that's what you get on the graticule.  See the image below for the switch markings...
My old HP180 does not have markings like this, so if I use a 1x probe setting, the switch marking is what I get on the graticule. If I use a 10x probe setting, I have to mentally multiply the switch marking by 10 to get the graticule value.

The other is, and this has been mentioned above by Mark as a possible source for bad readings, is where does the ground clip go in your circuit being tested?
If testing a simple JT circuit, do you probe the + output and clip the ground clip to the minus side of the battery?

The probe gives you the voltage between the clip and the tip. That's why I call the ground clip the "reference" because it doesn't necessarily have to be at the "ground" of the circuit under test. (For most scopes the clip IS grounded to the mains ground though). All the probe references should be connected to the same point though, and if the circuit under test is actually grounded, this should be the connection point of the probe references as well, otherwise you set up a groundloop condition.  But with a battery powered, ungrounded circuit like a JT, you can connect the "ground" of the probe at whatever point you want to use as a reference for the tip voltage.

If this topic is meant to be o'scopes 101, perhaps I should begin at a remedial level and work my way up from there?

Bill

[MarkE]

This is the kind of thing that scares me about scopes.  This is why I wanted to get a simple fg to produce known traces on the scope so I could see what they are supposed to look like.  I have learned here that most of the time, you use the 10x settings on the probes.  This is good info but...do we use that in our calculation of voltage and current when reading the traces?

In other words....I am on 1 volt/div. and the trace shows a peak of 3 divs.  I am on 10x probe setting.  Does this mean I am seeing 3 volts?  30 volts?  Or
.3 volts?  My scope (tek 2213) has the manual pouch bolted to the top of the case, which I did not like at first however, the manual did survive with the unit from the 80's so...it was a good idea.  I have read this many times but there are some simple things I can not figure out...the probe setting being one of them.

The other is, and this has been mentioned above by Mark as a possible source for bad readings, is where does the ground clip go in your circuit being tested?
If testing a simple JT circuit, do you probe the + output and clip the ground clip to the minus side of the battery?

If this topic is meant to be o'scopes 101, perhaps I should begin at a remedial level and work my way up from there?

Bill

Virtually all oscilloscopes let you tell them what the probe attenuation is, so that they display scaled to the original signal input.  On older scopes, they took advantage of the 1/2/5X progression of the attenuation steps.  A marker showed the gain for 1X three dial steps away from the marker for the 10X.