rusefi.com

Re: Choosing scope

2016-11-18T15:17:27

got that scope, but feeling more like a monkey)
hope to get to my ignition module and all that stuff by sunday, but I need tutorial on how to make the measurements (in addition to general dos and don'ts)
is there a way to damage the device by measuring higher voltage than is set on the screen? what do the switches on probes do? how to make measurements of the circuits powered from the same outlet as the scope?

Statistics: Posted by puff — Fri Nov 18, 2016 3:17 pm

Re: Choosing scope

2016-10-31T00:00:56

batronix seems to sell it for 380 euro shipped, which seems to be a good deal.

Statistics: Posted by puff — Mon Oct 31, 2016 12:00 am

Re: Choosing scope

2016-10-30T23:41:45

I've never come close to hitting the bandwidth limits of it. Remember a 100MHz signal is going to have problems when the wire is simply a couple feet long. However I could see how I could easily have a need for 100MHz specifically if we try to use clock frequencies in the 100MHz range on an MCU XTAL. I've always been able to see more than accurate enough, but I can also generally get the job done with less CPU cycles, which leads to lower frequencies and easier EMC designs. I also have trouble with only having 4 channels. At work we have 2 of these, such that I can do a hacked version of 8 channels. Don't forget your GND strap is a GND strap, so you can not put that little clip to anything other than a GND point. This means if you are measuring a high side resistor you need to use 2 channels and then put the scope into diff mode such that you are a looking at the difference between the two probes. When you are stuck with this situation, the 4 channels becomes 2 channels.

A lower cost and smaller scope would be the DSOQuad, it's lower quality, and smaller, but also less $. It can be easily modified to be 72MHz.
https://www.seeedstudio.com/dso-quad-4-channel-digital-storage-oscilloscope-p-736.html

Statistics: Posted by kb1gtt — Sun Oct 30, 2016 11:41 pm

Re: Choosing scope

2016-10-30T23:25:22

Hm. That sounds interesting. Probably, it's the first time a person with good knowledge in electronics discourages someone from buying an old CRT scope.

Initially I thought of buying an ancient Soviet one, single channel, which are avaiable sometimes for $30-40 here. Probably still not that bad decision.
But then I though, well, increasing the budget I can buy something more serious than a toy - from a company, which is considered to be the first mass-producer of scopes.

Yes, the footprint of these devices is indeed the major concern for me (not enough living space, unfortunatelly), which makes those old beasts a bit less relevant...

The 466 was available for somewhat $200, just 40 km from me, it included a manual. Probably, that offer is no more valid.
The second one is far away from me (Crimea) and somewhat $320 excl. shipping, and I am not confident about the seller.

What about Instek gos-620 ($250)?

Is there a good digital one but with less channels and cheaper? (I can't imagine why do I need four channels?) The one you recommended is available from Aliexpress, but as far as i got the price is more like $500. Might become a nice Xmas present... Will it allow to see those small spikes?

Statistics: Posted by puff — Sun Oct 30, 2016 11:25 pm

Re: Choosing scope

2016-10-29T00:18:50

Which is best one in world ... )))

Statistics: Posted by Abricos — Sat Oct 29, 2016 12:18 am

Re: Choosing scope

2016-10-28T23:26:54

Both are just about as bad. They are large, failure prone, and hard to fix when they break. Things are going to break, buttons are going to fail, caps are likely going to need re-forming. If you are getting something I would suggest Rigol ds1054z, it's 4 channels of powerful features for $400. If you shop around, you can some times find them on sale for $300 to $350 USD. They are much easier to use, and less prone to failures. If you are looking for accurate measurements, these older tek's needed to be turned on for like 12 hours so they can stabilize. The new stuff is accurate right out of the box.

The 466 is more obvious how it works, but also doesn't have the automagic measurement stuff. Simpler is handy because when a switch goes bad, it's easier to figure out that it's the switch. The 2246 has a bunch of "digital" brains which can go bad, then you have to diagnose if the switch is bad, or if the digital circuit has gone bad. I would suggest the 466 as it's simpler, but the measurements of the 2246 are handy. However the complexity of the 2246 is also going to make it fail more. Both are better than nothing, and it's not a huge difference between them in terms of ability to better measure noise. I would say get which ever one has better probes. Probes are a large part of getting a good noise free signal.

Statistics: Posted by kb1gtt — Fri Oct 28, 2016 11:26 pm

Choosing scope

2016-10-28T21:58:20

The shortlist includes tektronix 466 and 2246. Which one is better (to see the grounding problems, noise, etc.) and why?

Statistics: Posted by puff — Fri Oct 28, 2016 9:58 pm