Oscilloscopes
in [Design]
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From: Nico Coesel on 8 Feb 2010 15:36 D Yuniskis <not.going.to.be(a)seen.com> wrote: >miso(a)sushi.com wrote: >> On Feb 7, 1:57 pm, D Yuniskis <not.going.to...(a)seen.com> wrote: >>> RogerN wrote: >>>> What's the best scope to get for the money for mostly digital circuits? >>>> I'll have some analog but nothing real high frequency, like analog >>> But, your *digital* stuff *will* be "high frequency" (at least >>> considerably higher than the analog examples you mentioned) >>> >>>> connections to the microcontroller, maybe some SMPS circuits. I was looking >>>> at some microcontroller and fpga designs that you can get kits starting at >>>> less than $100 and going up with more speed and features. Also, I see on >>>> eBay you can get some nice looking Techtronics scopes for $350 or so, 4 >>>> channel digital, etc. Just wondering if something like the AVR scope would >>>> be a useful tool or if I would be wishing I went ahead and bought a nice >>>> used scope on eBay. >>> You might look into an older logic analyzer "for mostly digital >>> circuits". Often, the cost of shipping is the biggest expense! :> >>> >>> Of course, it also depends on the types of problems you are >>> trying to troubleshoot with the device... >> >> If you get a used logic analyzer, make sure it has the "pods". I'm >> simply amazed at how the box and pods get separated. > >Ah, yes. And, more importantly, any *micrograbbers* that >might be attached to the pods! Otherwise, you'll spend more >on *those* than the logic analyzer itself! :< The rate at which micrograbbers release themselves is e^number_of_grabbers per hour. Besides with current devices you're better of soldering thin wires directly to a header which connects to the pod. -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico(a)nctdevpuntnl (punt=.) --------------------------------------------------------------
From: Nico Coesel on 8 Feb 2010 18:02 mike <spamme0(a)go.com> wrote: >Drag it out and use it. You'll quickly learn what features you need. > > Do you have any recommendations on a >> used repairable scope? >Already done that TEK 465, 7704 and relatives. >The 7704 is handy 'cause you can get plugins for logic analysis, >spectrum analysis, TDR, curve tracer etc. >I've seen some recommend the Techtronics 465, since >> a lot of what I plan to use it on is digital signals/communication, I >> thought storage would almost be necessary. > >You need to say a LOT more about what you mean by digital >signals/communication. >RS-232 is communication and well within the capability of your leader. >Demodulating Cellphone signals is quite another matter. > >An oscilloscope is a poor substitute for good design judgment. That depends on the depth. If you get a DSO, get one with at least 1Ms record length and peak detection otherwise you'll miss glitches. >Once you get beyond that, it becomes complicated real fast. >Just probing the system is a nightmare. >Your problem is triggering on the desired event. You quickly get into >logic analyzer types of triggering and display. A two-channel scope >is better than one. 4 is better, but still not too helpful if you >need to trigger on 8 or 64. I once got so frustrated that I built a fixture >with a PAL on it. Reprogrammed the PAL for each complex trigger >and used that as one channel into a logic analyzer. I like the Tektronix logic analyzers for that. The trigger pattern (program is a more accurate description) can be quite complex including counters and stuff. >Digital storage has some benefits. >Lets you see what happened to signals WAY before the trigger event. >But you still have to come up with some way to trigger on the symptom. If the memory is deep enough you can just grab data and look through it. My logic analyzer has 4Ms per channel storage. I just trigger it on something obvious and look what is going on. >You can do a lot of stuff with a cheap analog scope. >Complex stuff needs $60K equipment. >There ain't much in between. Might as well go cheap >and suffer the consequences of not being able to do some stuff. >Patience pays off when you're looking for equipment. Indeed. There are many good deals on Ebay. IMHO second hand equipment from HP/Agilent or Tektronix is better than buying something new from a Chinese brand. I still need to replace my trustworthy Tek 2230 DSO but I still didn't find something that really fits the bill. -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico(a)nctdevpuntnl (punt=.) --------------------------------------------------------------
From: JosephKK on 11 Feb 2010 01:20 On Sun, 7 Feb 2010 23:24:33 -0800 (PST), "miso(a)sushi.com" <miso(a)sushi.com> wrote: >On Feb 7, 1:57 pm, D Yuniskis <not.going.to...(a)seen.com> wrote: >> RogerN wrote: >> > What's the best scope to get for the money for mostly digital circuits? >> > I'll have some analog but nothing real high frequency, like analog >> >> But, your *digital* stuff *will* be "high frequency" (at least >> considerably higher than the analog examples you mentioned) >> >> > connections to the microcontroller, maybe some SMPS circuits. I was looking >> > at some microcontroller and fpga designs that you can get kits starting at >> > less than $100 and going up with more speed and features. Also, I see on >> > eBay you can get some nice looking Techtronics scopes for $350 or so, 4 >> > channel digital, etc. Just wondering if something like the AVR scope would >> > be a useful tool or if I would be wishing I went ahead and bought a nice >> > used scope on eBay. >> >> You might look into an older logic analyzer "for mostly digital >> circuits". Often, the cost of shipping is the biggest expense! :> >> >> Of course, it also depends on the types of problems you are >> trying to troubleshoot with the device... > >If you get a used logic analyzer, make sure it has the "pods". I'm >simply amazed at how the box and pods get separated. I am not sure that i would even bother with used logic analyzers, USB pods are cheaper and usually fast enough (100 Mstates/s with glitch capture). If your speeds are greater than that you need to consider alternative data capture methods.
From: JosephKK on 11 Feb 2010 01:23 On Mon, 08 Feb 2010 20:36:24 GMT, nico(a)puntnl.niks (Nico Coesel) wrote: >D Yuniskis <not.going.to.be(a)seen.com> wrote: > >>miso(a)sushi.com wrote: >>> On Feb 7, 1:57 pm, D Yuniskis <not.going.to...(a)seen.com> wrote: >>>> RogerN wrote: >>>>> What's the best scope to get for the money for mostly digital circuits? >>>>> I'll have some analog but nothing real high frequency, like analog >>>> But, your *digital* stuff *will* be "high frequency" (at least >>>> considerably higher than the analog examples you mentioned) >>>> >>>>> connections to the microcontroller, maybe some SMPS circuits. I was looking >>>>> at some microcontroller and fpga designs that you can get kits starting at >>>>> less than $100 and going up with more speed and features. Also, I see on >>>>> eBay you can get some nice looking Techtronics scopes for $350 or so, 4 >>>>> channel digital, etc. Just wondering if something like the AVR scope would >>>>> be a useful tool or if I would be wishing I went ahead and bought a nice >>>>> used scope on eBay. >>>> You might look into an older logic analyzer "for mostly digital >>>> circuits". Often, the cost of shipping is the biggest expense! :> >>>> >>>> Of course, it also depends on the types of problems you are >>>> trying to troubleshoot with the device... >>> >>> If you get a used logic analyzer, make sure it has the "pods". I'm >>> simply amazed at how the box and pods get separated. >> >>Ah, yes. And, more importantly, any *micrograbbers* that >>might be attached to the pods! Otherwise, you'll spend more >>on *those* than the logic analyzer itself! :< > >The rate at which micrograbbers release themselves is >e^number_of_grabbers per hour. Besides with current devices you're >better of soldering thin wires directly to a header which connects to >the pod. In both cases the connector to the pod is going to kill you.
From: RogerN on 11 Feb 2010 06:29
I've been looking on eBay at logic analyzers, found some with pods and connectors, any recommendations? There are HP 1630A, 1630D, 1630G, 16500 and Tektronics 1225, 1240, 1241. Seems the most that have the pods are the HP with the velcro case on top. Or there are some USB logic analyzers that are in price range I'm looking at too. Probably my most advanced use might be to try to figure out Allen Bradley's RIO and DH+ communication so I could program a microcontroller to operate PLC5 I/O or some kind of HMI interface. Note this is for hobby use, if I have some sucessful designs they could be profitable but I'm not counting on it. Any recommendations on the logic analyzers I listed above? Or others to search for? RogerN |