Learn me: oscilloscopes

I'm building a new engine, and I'd like to be able to test/verify that all the trigger sensors are working before I try to run it. I've been meaning to start looking for an oscilloscope, and THIS thread motivated me to actually start searching. Turns out there are probably thirty for sale on Craigslist within an hour of me. Problem is that I don't know the first thing about them.

Care to share the basics? I am most interested in testing the hall effect sensors for crank position and cam position. Thanks!

Any of them will do that for you, and I've used mine for exactly that purpose. But in general, get a dual trace with as high a bandwidth (frequency spec) as you can find, if you can, although it is way overkill for what you want it for. When testing one out, there will be a 1V test signal available, so use that to see that it works.

I've been absorbing a lot through EEVBlog on YouTube. Video isn't the best way to learn it all, but it's been putting a lot of building blocks together.

For car use, if you already have a laptop, a Hobbylab Disco is a good unit. I use mine for in car troubleshooting a ton.

My day job is electronics, however I swing wrenches in the garage when I get home.

For the garage I have a two channel 60MHZ Tektronix analog scope. It's 25 years old and pretty slow by todays standards but is more than capable for automotive signals.

look for something 20 to100 MHZ. Actually 20 MHZ is plenty fast and anything more than that is overkill.

Analog scopes tend to be cheaper because they are old tech.

Two channel is handy and most scopes come that way.

Stay away from single channel scopes.

Tektronix is a good brand that you can get on CL in the $100 to $ 300 range.

Scopes need to be calibrated yearly if you want to operate them at the high end of the frequency rating The good news is automotive signals are so slow you can more or less ignore calibrating the scope.

I have an old oscilloscope but the pots for setting it to different voltage ranges(and the like) aren't finite. I get some good looking sine waves but with out a definite scale, I find it a bit useless. Of course the scope was build as part of a ITT at home class from the 70s or 80s.

Anyone use their soundcard for an oscilloscope? Or the android ones?

Those things are real? I thought they were just movie props.

I have a 20 year old dual channel Techtronix THS710 60MHz Tekscope. It's portable and reliable. It's a little slow by today's standards but there hasn't too much I need to play with that switches faster than that.

The portable part is why I bought it originally - I was working at customer sites and needed something small and tough to throw into airport baggage. As it turns out - it also works awesome in my garage and/or trailer at the track.

One of my friends got one of those oscilloscope accessories for his laptop computer and used it for troubleshooting the Megasquirt he built for his car. I don't recall the brand, but it was inexpensive and worked pretty well. There are a number of them out there on the market.

I was pretty sure that said colonoscopies. After further review, I am much less concerned.

Link to the one I use: http://www.hobbylab.us/p/53/usb-oscilloscope-disco-2

Only downside is that is shares a name with an unreliable SUV.

Great advice so far, right on the nose.

I could only offer info on the ones I use at work, but even a hospital's pocket book has trouble coughing up the dough for them.

Not sure where you live, but a local college may have a cheap one for sale. At u of M I see them for sale in the $30 range pretty often.

I'm personally staying away from the modern mini units. Since one of my primary goals is to learn how the damned things work, an old analog oscilloscope is what I'm looking for. If they were easier to find around here, I'd probably have a couple already.

There are also some kits that let you use your smart phone as a scope, through the microphone jack. No experience, just think it looks interesting.

Do you want to learn how they work, or how to use them effectively? Its a much different thing, the former would start with an explanation of wtf a cathode ray tube is and why we even ever used them ;)

For me, both. I already know all about CRTs, what they are, how they work, and why many still prefer CRT oscilloscopes, or at least keep one laying around.

Learning more about how they work helps to understand how to use one effectively. The same goes for every tool I've ever used, all the way down to the lowly hammer.

For a beginner the digital units are easy and most new ones come in color. At work, I have a choice of an old school Hitachi digital with green CRT or a new tektronics LCD color scope. I prefer the old school with the CRT.

CRT scopes can be digital or analog and are larger in overall size. Obviously LCD scopes are digital.

Analog scopes are yesterday’s technology , but are still great units for automotive use. The CPU’s in the various PCM’s and modules run fast but chances are you will never use a scope on them. The signals generated by the engine sensors are pathetically slow commonly range between 1 and 1000 Hz.

Tektronics builds a good scope and most old school techs prefer them.

Hitachi is a good choice

Tenma, Gould, Goldstar, Kenwood are fine but I would avoided older ones because I’m ignorant and prefer Tektronics.

Some older analog scopes have fancy gizmos for specialized purposes. Tektronics offered various gizmos and are nothing more than annoying. Most special features can be more or less turned off or ignored.

20 MHZ is commonly the slowest in modern Oscilloscopes. You can get 5 and 10 MHZ scopes but that borderline antique. Plenty of good 20MHZ scopes still around. You can certainly get faster units but it will not be of any benefit.

Some or most Oscilliscopes should never be used to monitor its own power source. What I mean to say is you can’t use the scope to monitor the 120V A/C that it is plugged into. You need to run an isolation transformer to monitor any A/C voltage that the scope is also using for power. Some scopes have built in transformers and some don’t. Generally it’s a good idea to avoid plugging the probes into the wall socket to “see” the A/C power of your house.

They are available almost daily on shopgoodwill.com Watch for one that isn't on the other side of the country to reduce shiping.