20-50 Mhz Analog Scope Limitations for automotive.   - Page 1
Forum section: electronics / testgear

author: Ford515Grandpa
author_rank: Newbie
timestamp: April 19, 2020, 04:31:25 am
content: I was thinking of purchasing an old Analog 20-50 Mhz scope to experiment with some hobby electronics so that I can better understand electronics. In addition, I also was thinking I could use it to check out some automotive current and voltage waveforms. Perhaps relative compression tests, fuel injector ramps etc. primary ignition on older cars and compare to new. Do any of you use an older analog scope for Automobile diagnosis and if so what can I expect and what limitations will I find?

author: james_s
author_rank: Super Contributor
timestamp: April 19, 2020, 04:46:16 am
content: I used one for some automotive testing back when an analog scope is all I had. The biggest limitation I had was the size and bulk of the thing, it was difficult to find a good place to set it near a car that isn't in the way, and it's difficult to see the screen in sunlight. Also you probably want to be careful not to get oil and grease on your scope. Most of the waveforms you find around an engine are repetitive though so analog works ok.

author: tautech
author_rank: Super Contributor
timestamp: April 19, 2020, 05:31:00 am
content: Quote from: Ford515Grandpa on April 19, 2020, 04:31:25 amForgettaboutit ! Really do throw using a CRO for this right outta your mind and focus on getting a DSO for it.Anything you get the chance to see is just that, chance and only while you have a truly repetitive and stable waveform whereas a DSO can be set to single trigger on events and capture them for study/analysis.

author: maginnovision
author_rank: Super Contributor
timestamp: April 19, 2020, 06:43:53 am
content: An analog scope is ok for most engine related stuff. Fine for most sensors, ignition, injection(signals don't get much more repetitive than a running engine) etc... It would be very cumbersome though and a handheld DSO is what I'd recommend. You can pick up an older philips/fluke 50MHz model for not too much and it'd be easier to work with and single shot is handy for getting a picture and looking at it, possibly comparing to reference waveforms since at first you may not be sure what you're looking at/for.

author: David Hess
author_rank: Super Contributor
timestamp: April 20, 2020, 03:15:38 am
content: Quote from: tautech on April 19, 2020, 05:31:00 amEngine test analyzers were based on analog oscilloscope like displays for a long time and worked fine.

author: maginnovision
author_rank: Super Contributor
timestamp: April 20, 2020, 03:34:49 am
content: Quote from: David Hess on April 20, 2020, 03:15:38 amI started with old snapon units. Definitely work but there are easier ways to work now.

author: Ford515Grandpa
author_rank: Newbie
timestamp: April 20, 2020, 01:26:21 pm
content: Thanks Fellas for all the replies.I am looking forward to experimenting.I am thinking that if I am successful at not blowing up the $65 one I just bought, I would like to pick up a reasonable Digital one sometime in the future. No plans on making this my permanent diagnostic unit. Plus if this one survives, it would be nice to give it a stable home at my workbench and perhaps give it to my grandson one day.For right now, it should be a good tool to help me learn how to keep the smoke in the machine.Best and Thanks again.

author: BillyD
author_rank: Regular Contributor
timestamp: April 20, 2020, 03:56:27 pm
content: I guess you can work around it if you really absolutely had to. But if you want to, say, examine a relative compression waveform or compare injector waveforms, etc it's a whole lot easier to capture them first and then examine/compare them after.

author: james_s
author_rank: Super Contributor
timestamp: April 20, 2020, 04:07:33 pm
content: Sure, digital is better, but coming from no scope at all an old analog scope is a huge step up. I used analog scopes for many years when that's all there was, at least all that was even remotely affordable as a hobbyist. They take a bit more work to use but they get the job done.

author: maginnovision
author_rank: Super Contributor
timestamp: April 20, 2020, 06:03:30 pm
content: Yea, it's a common hobbyist dilemma. Do I want to get what I consider to be the ideal instrument or buy something cheap potentially wasting the money if it is too cumbersome or doesn't work for your use case. Also potentially the cheap instrument serves its purpose and gives you a better idea of what else you might want/need or you even find it's perfectly fine.It's up to each individual to figure it out for themselves.

author: tautech
author_rank: Super Contributor
timestamp: April 20, 2020, 07:29:04 pm
content: Quote from: maginnovision on April 20, 2020, 06:03:30 pmOr accept the advice from those that have been there and done that.I've diagnosed faulty ignitions in drag cars with a DSO when the owners couldn't work out what the issue was under max power and boost ......not enough output from the ignition pack to one coil.The capability of the modern DSO is more limited by its operator than anything else.

author: maginnovision
author_rank: Super Contributor
timestamp: April 20, 2020, 07:31:22 pm
content: Sure but your advice saying spend more money doesn't always work. Spend more money is always the easy advice, but not so easy for some to implement. Also, the advice is part of what people use to make their decisions. It's not guess my way through or take advice. It's take advice and consider my own requirements.

author: tautech
author_rank: Super Contributor
timestamp: April 20, 2020, 07:51:24 pm
content: Quote from: maginnovision on April 20, 2020, 07:31:22 pm100% agree if you have the knowledge and understanding of those requirements, you'd be surprised in the general hobbyist market how few have a good grip on their needs and don't always consider how those also might grow as their knowledge increases. Mine certainly has.Generally, you get the capability you pay for ......plus reliability and warranty when buying new.

author: james_s
author_rank: Super Contributor
timestamp: April 20, 2020, 09:16:51 pm
content: I could not care less about a warranty, I usually void whatever warranty something may have had and repair it myself because it's faster and less hassle than sending something in for warranty service. Buying new is for people who have money to burn or need their tools to earn money.The OP paid 60 bucks for a scope, and I have little doubt they'll get more than 60 bucks worth of education, enjoyment and utility out of it. There is no decent DSO you can buy for 60 bucks, they would have to spend at least 4-5 times as much to get anything worth getting. Maybe they'll eventually decide to get something more, maybe not, maybe the old analog scope will end up satisfying all of their needs. Again I got by for 20+ years with nothing but analog scopes and before that I got by with no scope at all because they used to be far too expensive for me to afford. People who have access to all the latest gear seem to forget that there is a whole world of things that can be accomplished with old tools, the entire foundation of electronics was developed using old analog instruments because that's all there was. Engineers like the legendary Jim Williams and Bob Pease worked developed and debugged their magic with analog scopes. They are just as useful today as they ever were and for a hobbyist it is not important to have the latest gear.

author: joeqsmith
author_rank: Super Contributor
timestamp: April 20, 2020, 11:41:30 pm
content: Quote from: Ford515Grandpa on April 19, 2020, 04:31:25 amI've lugged my old analog scope in the car with an inverter to power it a few times. I've also taken it with me to work on the bikes more than once. It's far from portable. AC power is always an issue. With it being analog, it's been a problem to hunt down intermittent problems. A few years ago I ran across a guy with a couple of old Fluke 97 scope meters. I bought these and gave my analog scope away. The original owner of the Flukes had the training video (VHS). Fluke authorized me to offer it free of charge on Youtube. It may be of some interest to you as it is exclusively for automotive applications.

author: maginnovision
author_rank: Super Contributor
timestamp: April 20, 2020, 11:50:56 pm
content: Yea, for automotive it's my opinion those old fluke digital scopes are the gold standard. I still have my 98 series II(Not exactly the same) and had a 97 but got rid of it when I got my first bench scope. They have newer ones but they don't offer much for the specific use(unless you move up to the 4 channel models). If the OP tires of the analog it'd be my #1 recommendation to add a 97 to the collection.

author: Ford515Grandpa
author_rank: Newbie
timestamp: April 23, 2020, 05:43:48 pm
content: Thanks again fellas. It arrived today. Probes and a few other accessories later tonight. Hopefully it is still in tact tomorrow. Anyway, does Dave have some good beginner get to know your scope videos that you know of or is there someone else on the you tube that has a reasonable curriculum? I looked and clicked on some of the ones I thought would be intro videos, but they seem to be like talking a foreign language to me a bit. I think I need something to get a foot wet rather than a whole leg.