Oscope Selection

ov10fac: Thanks for the information. What would be the advantage of a 4 channel other than the obvious ability to view four signals at once. Right now I'm having difficulty visualizing why I would want to see two channels at once.

The utility gained going to two channels over one in that one can see the simultaneous relationship between nodes in a circuit. For a lot of problems this is nearly indispensable and I would strongly recommend anyone buying a scope get at least a dual channel model. My single channel Hitachi has a separate "trigger" input so it will trace on some other event, but that's difficult to set up when you can't see the event on which you're triggering.

Four channels is more luxury than necessity, particularly if one has access to a logic analyzer, but the up charge amortized over the length of time I tend to hang on to things would have been worth it to me.

quadrature encoding would be difficult with only one channel.

Ok,

So at a minimum 2 channels, 100 mhz, and since I will primarialy be using this for Arduino and Raspberry Pi projects what sample rate would be the recommended? Besides the basic passive probes, are any other probes recommended? Thanks.

differential probes are nice but not necessary and same with current clamp... there are ways around this and both those options get expensive.

With the math function two channels used with Math '-' become a crude differential probe.

So 4 channels allows 2 differential signals to be compared.

For battery circuits that are uncoupled from mains ground this is not an issue.

MrMark: It's noisy at the lowest signal resolution (10 mV/division).

That may be partly because of the high impedance and high bandwidth - some of it is real noise. Set the probe to x1, ground the tip, it should decrease noticably.

Noise depends on the square root of bandwidth and square root of source resistance. At 100MHz and with 1 or 10Mohm this is a considerable amount.

I know this is a pretty old O-Scope, but would it be a good one for a starter scope? If it would be a good starter, I will make an offer.

Here is the URL from the Craigslist posting:

https://omaha.craigslist.org/ele/d/omaha-lg-os-mhz-oscilloscope/7108389248.html

Thanks.

Looks like it has everything but the 10 meg probes. Make sure the seller demonstrates that it functions properly.

Paul

Paul_KD7HB: Looks like it has everything but the 10 meg probes. Make sure the seller demonstrates that it functions properly.

Paul

I just checked and there are no probes. So I would need to purchase a set of 10 mg probes which adds to the price. I see the same scope on ebay for 50-100 so i may make an offer pending proof of operation.

Paul_KD7HB: Looks like it has everything but the 10 meg probes. Make sure the seller demonstrates that it functions properly.

Paul

Excuse my ignorance, but how would I test to make sure it works properly. What tests should I run to validate proper functioning.

ov10fac: Excuse my ignorance, but how would I test to make sure it works properly. What tests should I run to validate proper functioning.

First look at the trace to see if you can adjust the width and focus.

Next connect the 10 meg probe to each channel and put your finger on the bare probe tip and see if you can see a signal of any kind.

Next connect the probe to each channel and the tip to the built-in calibration pin. Should get a nice square wave. If the probe is adjusted properly the corners of the square wave should be REALLY square!

Then be sure there is or you can get a manual. The manual will show how to use all the other scope controls and what they do. But that is beyond a basic test of the device. My Tektronics manual is about an inch thick, but other manuals, not so much.

Paul

ov10fac: I know this is a pretty old O-Scope, but would it be a good one for a starter scope? If it would be a good starter, I will make an offer.

Here is the URL from the Craigslist posting:

https://omaha.craigslist.org/ele/d/omaha-lg-os-mhz-oscilloscope/7108389248.html

Thanks.

An analog scope is handy. But are you aware that $349 gets you a modern 4-channel digital scope with tons of functions...The Rigol DS1054Z. I have the earlier DS1052E (bought for $399) and use it a lot and am considering upgrading to the DS1054Z.

MK1888: An analog scope is handy. But are you aware that $349 gets you a modern 4-channel digital scope with tons of functions...The Rigol DS1054Z. I have the earlier DS1052E (bought for $399) and use it a lot and am considering upgrading to the DS1054Z.

Yeah, I am really at odds about going used analog like this LG or a new digital like the one you recommend. Think I will ponder that a little more and wait to see if a newer model show up on CL. Many thanks for the thoughts.

This guy knows his electronics, it's his occupation:

Rigol DS1054Z Oscilloscope Review

EEVblog #926 - Introduction To The Oscilloscope

Thanks for the links to the Youtube videos. They will be very helpful.

Just for completeness, and in case others with very limited budgets read this, there is also the option of the DSO150 "Shell" scope from JYETech. It's a very low frequency (they claim 200KHz) single-channel scope available in kit form or assembled from Banggood (known to have genuine stock, not clones). The assembled scope with a probe currently sells for US$21 plus about $3 shipping:

https://www.banggood.com/Original-JYETech-Assembled-DSO-SHELL-DSO150-Digital-Oscilloscope-Module-9V-p-1211151.html?rmmds=search&cur_warehouse=CN

In addition you would need a 9V power supply with the right barrel connector. However, I converted mine to LIPO battery power, which has the additional advantage that the scope isn't referenced to ground, so you're less likely to blow it up, and you can do things like measuring, and triggering on, the voltage drop across a mosfet.

Of course this is limited in what it can do, but I have found mine to be surprisingly useful for Arduino stuff. It works with PWM, steppers, servos, IR remotes, audio, and other similar things. I recently repaired my Disney coffee mug warmer after using the scope to detect a very brief dip in the 5V power supply which was resetting the MCU. Turned out to be a bad electrolytic capacitor (surprise!). And using its 1K test squarewave, I was able to use the scope to see the very high ESR of the cap even though the capacitance test was fairly normal.

Anyway, for under $30 including a power supply, you get a basic slow scope. And if you blow it up, you haven't lost much. It has Auto, Normal and Single triggering, but because of limited capture memory, the trigger only works at 20ms and faster per division, but that's usually not a problem. And it has data readout - frequency, etc.

If you do get one, get it from Banggood. The clones on Ebay and Aliexpress will not take firmware updates, and yes, these dinky little things do get firmware updates from time to time. And JYETech has a forum if you have questions. There's a long thread there on battery conversion options. So this is not junk. It's a quality product, with support, for a very low price. And even if you do eventually upgrade to a "real" scope, you may find yourself still using this one more often than you would expect.

Many thanks. Think I'll pick one up while I am debating what "real o-scope" to buy.

I should have mentioned that there are number of Youtube videos on this scope on both kit construction and operation. Just search for DSO150.