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Gloyale

Using an Osciliscope?

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Hey ya'll.....

 

I recently picked up an old (not TOOO old) osciliscope for examining the "crossover" action of oxygen sensor voltage. Also thought I could use it to look at the Duty C output for transmissions, and possibly Cam and Crank sensors.

 

Problem is, I am not really sure how to use it?

 

Could someone tutor me? Or have a link to a good sight to describe using an Osci to look at 12v DC PWMs?

 

Thanks to anyone in advance

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i used to use them in aerospace engineering programs and have since forgotten everything. but even then, i used them more than understood them if that makes any sense (like your customers GL!!!!).

 

did you try searching at all, like just a quick google search to see what's out there? i'd probably start there or in a library. but who's got time for that right?

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The really arent that hard to use. It's easier to show you unfortunitly then tell you since there are some variations between models as to actual controls.

 

Did it come with wires?

 

What make and model is it.

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Not trying to hijack, but has anyone ever used an ociliscope to view the

frequency going to speakers?

And if so have you run an LED to the output so that it lights up as the volume

increases?

 

Twitch(?)

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An oscilloscope typically will display on an X vs Y graph format. the X or horizontal direction is set by the sweep speed generated by the oscilloscope internally. You control this speed on the front panel. the vertical or Y signal is picked up by a probe. This would be your signal from the car circuit that you want to test. The voltage applied to the input needs to be matched to the probe and the input voltage range on the control panel.

 

What kind of 'scope do you have? Do a google search on "oscilloscope tutorial", and you will find some good sites.

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thanks for the suggestions.

 

I do believe the scope is a tektronics. It's at the shop

 

I understand what the graph displays.

 

I am just a bit unsure of what some of the control settings. And I don't to hook it up in a way that is going to fry anything.

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A good source for info on older electronics is at http://www.bama.sbc.edu/ "BAMA" stands for Boat Anchor Manual Archive, and is a great database on older electronics, especially vacuum tube equipment. Follow the Tektronic link on the site, they may have your 'scope manual available for download. There is a mirror site for BAMA, I think its http://www.bama.edebris

Edited by shadetreemech
add information

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Basically...

 

The Y axis will show voltage. There will be a knob to change the volts/division that it shows. The graph on the display will be broken into divisions.

 

The X axis shows time. There's a knob to change the seconds/division.

 

Most scopes have at least 2 input channels, so you can look at up two different signals. There is another knob to show/hide each channel, and to trigger off one channel or the other. Make sure they are all set to the channel you're using.

 

If any of the above aren't set up right, it just won't show anything.

 

To hook it up, just connect the ground lead to ground, and the tip to the signal you want to measure.

 

You can start by hooking the probe up to the battery. You can see how changing the volts/division changes the scale on the display. At 5v/div the battery should read at just over 2 divisions.

 

-Dave

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Tektronics is one of the best names out there, they will have a manual for it.

 

 

nipper

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Sweet guys, thanks for the help.

 

I will have a chance to play with it later in the week.

 

 

BTW it is not tektronics.

 

It is a Telequipment. Model S54A

 

Soem of the probes I have for it are tektronics

Edited by Gloyale

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These days you can get digital gauges that can do all those measurements you mentioned, and a lot more dependably too probably.

 

Even better you could connect a laptop to the ecu and log all the data for reviewing later and as you compare other readings to it like time or temp or speed.... or everything your ecu reads or sends out as it runs.

 

What ocilliscopes are really good for though is reading really high and really fast voltages... like spark plugs, which most gauges wont do(unless you spend a fortune).. That's what I'd use it for.

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These days you can get digital gauges that can do all those measurements you mentioned, and a lot more dependably too probably.

 

Even better you could connect a laptop to the ecu and log all the data for reviewing later and as you compare other readings to it like time or temp or speed.... or everything your ecu reads or sends out as it runs.

 

What ocilliscopes are really good for though is reading really high and really fast voltages... like spark plugs, which most gauges wont do(unless you spend a fortune).. That's what I'd use it for.

 

I can stream the data from OBD II vehichles on my code scanner, but no easy way to live stream data from the pre-96 cars.

 

Besides, O2 sensors DO produce a very fast voltage swing. Mulitmeters just show you the average, not the actual widtrh of the swing, which is important for O2 sensor diagnosis.

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Hi,

it's easy to connect to older cars these days, check out a bit of software called Evoscan or Hiscan.

 

O2 sensors range several times a minute, even an analouge gauge can keep up.

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The advantage of a 'scope is it's flexibility. You can set it up to get a live display of the spark impulse at #3 cylinder. You can sample the voltage signal from an oxygen sensor, and slow down the scan so that you can watch the variations occur. You can display the 7 megahertz amplitude modulated carrier from your WW2 vintage amateur transmitter, and control for overmodulation. And there are top-quality lab grade scopes (Tektronic or Hewlett-Packard) that sold for thousands in the mid-70's, that you can buy for a couple of hundred bucks. It's all in what you want to play with, and how much self-education you want to do. It's just a tool, but if you know how to use it, a powerful tool.

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for two bucks!!! If it works, that was a sweet deal!!!

 

A general comment to all oscope users:

Don't neglect the XY function. This shows the voltage of one channel on the X axis, and the voltage of the other channel on the Y axis. This is very useful if you want to see how a particular component responds to an input signal.

 

One of the initially difficult features of an oscope for first-timers is the trigger. On newer oscopes, there is an automatic trigger setting (and it is usually the default), but on older ones (like the one in the picture above), you may be required to set the trigger manually. The trigger is a setting that tells the oscope to sweep the trace, and, if it does not detect the trigger, then it will just sit idle. For example, if you are trying to see a waveform that swings from 0 V to 5 V on Channel 1, but your trigger level is set at 10 V on Channel 1, then you will not see the waveform. Another example: if you are trying to see a waveform on Channel 1, but you are triggering on Channel 2 (that is not connected to anything), then you will not see the waveform.

 

The trigger is not necessary in XY mode.

 

Closely associated with the trigger (actually, a feature of the trigger) is the hold off (or delay). This is especially important for slow signals. If you trigger too often, you may not get a good look at your signal.

Edited by turin

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