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15 Mhz Oscilloscope - WITH NO PROBES!!

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CozzyElectron

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Hi all, this is my first post in this forum as I just joined.

I bought an old oscilloscope at a garage sale last summer and it came with no probes.

I was wondering what kind of probes I'll need and where can I get them? I'm assuming ebay..?

It's a:
Gould Advance 15 Mhz OS 255
Serial # 203


Underneath each of the probe inputs, it says:
1M ohm 28pF

Could that be my clue to what kind of probes I need?

I'm a total useless nubie as you can see.

Looks like:
135571-gould_os255_2_channel_15mhz_oscilloscope_rse.jpg


Any help would be muchliest appreciated :)

Thanks!

CozzyE
 
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Ebay has some good deals if you don't mind the wait. There are some probes for $2.95 USD each at 20 Mhz on Ebay. You can go over on the rating and it will work.
 
I've never used an oscilloscope before so my quesions will be inane:

Do I need 2 probes?

What I want to do is see the wave form of the stray voltage in my home as see on this video I saw:
 
Scopes come in 50 and 1 meg flavors when you use external probes. The 50 ohm ones aren't cheap at all.

You can get way off on the capacitance (pf). A general purpose probe would be a x1,x10 switchable. You can only 'compensate' a x10 probe.

Compensate means adjust the probe so it's a perfect /10 divider and square waves will have nice edges. You use the Cal output on the scope and adjust a screw on the probe so the waveform has nice edges.

High bandwidth probes cost more. ebay should have some nice <=100 MHz. x1, x10 probes for a reasonable price. Sometimes they are sold in pairs with a kit of adapters.

You want a probe with a BNC connector on it.

It does get more complicated than what I described.
 
Hi,

Just a quick note or two...or three...

If you have a dual input scope then you really want TWO probes not one. That's so you can look at two signals at the same time and compare them in real time. This is extremely important for some circuits.

You will want at least one probe that does 10x. That's because the 10x probe can go up higher in voltage than a 1x probe. The scope input also ahs a max voltage rating that you cant exceed or you'll blow the scope input amplifier. With a 10x scope you can view waves that are 120v or maybe higher for example but with a 1x probe you might only get to 20v, but it depends on your scope too so you have to read the specs for that scope. If you need to compare two waves of somewhat higher voltage like 120v, then you need two 10x probes.

The frequency probably isnt as important here because the scope only goes up to 15MHz, but see what you can find.
 
thanks MrAl and KeepItSimpleStupid...

appreciate your input. Its all a bit confusing for me but I AM learning.

MrAl, your insights were particularly illuminating. I think these probes are x1 and x10 ... so, it looks like I could buy these.

Just wondering, will all probes fit to all scopes?

I just don't want to spend money and have the probes shipped all the way from china and they dont fit!

That would be a waste.
 
Hello there,


Well from the pictures they do look like they would fit. Most scopes have a "BNC" connector for the probes, and those probes do look like they have that, but it's nice to see it in the product description too like "These probes have BNC connectors at one end" or something like that. The description does have that so that's good.
Also, the 1x probe states that is has "1Megohm input" which means it should match up with a 1Megohm input scope.

If you are still in doubt though the best bet is to contact the seller directly and ask them any questions and see what they say.
 
...............................

If you have a dual input scope then you really want TWO probes not one. That's so you can look at two signals at the same time and compare them in real time. This is extremely important for some circuits.

You will want at least one probe that does 10x. That's because the 10x probe can go up higher in voltage than a 1x probe. The scope input also ahs a max voltage rating that you cant exceed or you'll blow the scope input amplifier. With a 10x scope you can view waves that are 120v or maybe higher for example but with a 1x probe you might only get to 20v, but it depends on your scope too so you have to read the specs for that scope. If you need to compare two waves of somewhat higher voltage like 120v, then you need two 10x probes.
......................
Another reason to use a 10X probe setting is that it greatly reduces the probe capacitance. This can be particularly important at higher frequencies where the probe capacitive reactance can significantly load the node being probed. For example the 100pF or so capacitance of a 1X probe has an impedance of only about 1.6kΩ at 1MHz and 160Ω at 10MHz.
 
Regarding your post #5 with the video, You do not need a probe or probes. The probe used in the video was likely a X1 probe or an X1 X10 probe set to X1. Set your scope up for a free running trace at about 5mS or 10mS per division. Set the scope to use a single vertical channel and set the channel to around 5 or 10 mV per division. Now take a standard paper clip and fold it open. Place the extended leg of the paper clip into the center of the BNC vertical input connector. Your body is acting as an antenna and picking up all the noise around you and you should see it on the scope. So if your main concern is to see what is seen in the video you do not have any need for a probe.

I also tend to disagree with the video as to any harmful effects which is why when the author contacted the power company they told him to go away nicely. However, that is another story.I have read the MSU study regarding the dairy industry which reads in part:

How does stray voltage affect animals? Stray voltage does not directly affect cows but
indirectly through avoidance behavior. When cows change their behavior it can affect
their performance. Cows may avoid drinking, eating, letting down their milk or entering
stalls. If cows are nervous in the milking parlor, they may not milk out properly, which
can affect production and health. If cows receive a shock when drinking or eating they
may consume less and affect production. Or, if cows receive a shock when they enter an
area, they may avoid that area making management more difficult.

I certainly can't fault the cows. If every time I went to get a drink of water I received a shock I would curtail my water drinking. :)

Should you want probes for other measurements then most of what was linked to will do just fine. Just remember you do not need a 10X probe or a 1X probe to duplicate what was shown in the video.

Ron
 
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Agreed. One might want to look at that signal differentially using (A-B) as well.

These **broken link removed** are the kind of kits your up against, A BNC adaapter, hook adapter, an IC pin adapter and a pointy probe adapter. The compensation range is a bit higher,

Note on the probe you selected, there is a hole near the BNC. That's used to adjust the capacitance with a screwdriver.
 
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