A good digital oscilloscope?
in [Design]
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From: Joerg on 13 Dec 2009 12:02 Tim Williams wrote: > "JosephKK" <quiettechblue(a)yahoo.com> wrote in message > news:vr5ai5tjh0b59t76e4362bufh7ufgp0n97(a)4ax.com... >> The last time i saw a synchronizer type 'scope was over 40 years ago, it >> was a neighbors prize possession and 10+ years old even then. > > http://webpages.charter.net/dawill/tmoranwms/Elec_Scope1_lg.jpg > > Well, it says "TRIG LEVEL" on the outer knob, but it has this peculiar > "STABILITY" on the inner knob. > > I never did completely understand the circuit in this thing (I have the kit > instructions, so I have all the drawings), it's drawn so as to make a > minimum of sense. > They work similar to an injection oscillator where mildly force-feeding it some signal makes it synchronize to that signal. More or less, depending on how strong you tie them together. Problem with synchronizer scopes is that the user really has to watch it. Crank up the stabilizer knob too much will make it appear rock stable but will distorte the signal that's being shown. IOW, what you see is not necessarily what you get. The X-axis (time) becomes non-linear. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: JosephKK on 13 Dec 2009 12:46 On Fri, 11 Dec 2009 16:19:47 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com/Snicker> wrote: >On Fri, 11 Dec 2009 14:55:01 -0800, Charlie E. <edmondson(a)ieee.org> >wrote: > >>On Fri, 11 Dec 2009 11:32:44 -0800, Joerg <invalid(a)invalid.invalid> >>wrote: >> >>>Joel Koltner wrote: >>>> "Joerg" <invalid(a)invalid.invalid> wrote in message >>>> news:7ob08jF3oortqU1(a)mid.individual.net... >>>>> But wait, $600 for a Christmas gift? Ain't that a bit over the top? >>>> >>>> Only a little... I think that $250-$500 per kid for Xmas today is not at >>>> all uncommon today... >>>> >>>>> As a kid I had to work for stuff like that. For example at a meat >>>>> factory until I had the $400 for my first used and pretty banged up >>>>> HW100 transceiver. >>>> >>>> I doubt you can legally work at a meat factory unless you're at least 18 >>>> today. :-( >>>> >>>> If you want to see some kids with wealthy parents who are *seriously* >>>> spoiled, check this out: >>>> http://www.mtv.com/shows/sweet_16/episodes.jhtml . It's not uncommon on >>>> that show for the parents to blow $25-$100k on their kid's 16th birthday! >>>> >>>> If I had the choice between a Lexus and, I dunno, a Civic and a bunch of >>>> test equipment, I think it'd be obvious which I'd choose... >>>> >>> >>>What I really don't understand is when a couple goes into big time debt >>>just for the wedding ceremony, and often the bride's folks as well. I've >>>heard of one couple who "had to" sell their home and move into an >>>apartment to give their daughter an "appropriate" wedding. >>> >>>We made sure that neither of our parents had to pay anything and that >>>our wedding ceremony was reasonable and could be comfortably paid from >>>our savings (without raiding the account). Credit card use for the >>>wedding was zilch. >> >>Ah, Jeorg, we are so much alike! >> >>When we got married, we were still in college, so had a small ceremony >>there. We paid for the flowers, the photos (a real mess, but then we >>were young then, and didn't know to get things in writing!) the cakes, >>etc. We didn't even HAVE a credit card at the time! Her folks helped >>out on some of the expenses, and her mom made the dress. I just >>rented a tux. It was simple, and inexpensive, and still very >>memorable! >> >>Charlie > >Went to the minister's house and got married for FREE... >_50_years_ago_this_coming_March_31_ ;-) > > ...Jim Thompson Look him up and have a nice dinner with him about that time (provided 'e is still around). (Or on some chance her).
From: Jan Panteltje on 13 Dec 2009 12:46 On a sunny day (Sun, 13 Dec 2009 09:02:40 -0800) it happened Joerg <invalid(a)invalid.invalid> wrote in <7okl1iF3qgfqrU1(a)mid.individual.net>: >They work similar to an injection oscillator where mildly force-feeding >it some signal makes it synchronize to that signal. More or less, >depending on how strong you tie them together. Problem with synchronizer >scopes is that the user really has to watch it. Crank up the stabilizer >knob too much will make it appear rock stable but will distorte the >signal that's being shown. IOW, what you see is not necessarily what you >get. The X-axis (time) becomes non-linear. Then the design is wrong. Consider this circuit: -------------- + | | |--- [ ] R2 -->| Q1 | | |--- | | | |-------------------- | [ ] R1 | | -------| |---- [ ] R3 |----\| Q2 UJT | | |---- \| Q3 | | |---===---< Sync pulse === [ ] R3 </| NPN | C1 | | /// /// /// The free running oscillator is the unijunction formed by C1 Q2 R2 R3. Q1 with R1 forms a constant current source, causing a linear positive ramp on C1, that ramp is buffered, amplified and fed to the horizontal deflection plates. The amplitude is such that the scan is a big wider (ends a bit past) the end of the graticule on the right. The Venier speed ('stability?') is set by R1, and set a bit lower in frequency (or fraction of that) then the signal observed. When a sync pulse comes, point R2 Q2 is pulled down a bit, set by the ratio of R2 and R3, and the trace ends early, because the UJT will always fire at a fixed part of the voltage, and the retrace starts . This effectively increases the frequency of of the oscillator. There is *no* distortion in the linearity, There is *no* change in the speed (charge current of C1), so 1 cm represents the same time on the scope, only the trace gets a bit shorter, but still long enough to cover the graticule.
From: JosephKK on 13 Dec 2009 12:55 On Mon, 07 Dec 2009 06:17:00 -0500, JW <none(a)dev.null> wrote: >On Sun, 06 Dec 2009 19:45:24 +0000 info_at_cabling-design_dot_com(a)foo.com >(DA) wrote in Message id: ><c2690$4b1c09d4$43de0cc0$11122(a)news.flashnewsgroups.com>: > >>Hi all, >> >>I think I'm going to try and treat myself to an oscilloscope this >>Christmas. I've managed to go without one for the last 15 years or so and, >>frankly, did not have a burning need or even much space for it. I do some >>digital design (PIC based mostly) - LED, motor controls and such and >>every once in a while I wish I has something to look at the signal with. >> >>So, I've looked around and saw this name come up often: Rigol DS1102E >>100MHz Digital Storage Oscilloscope. There is also a 50MHz version which >>is what I think I need. There has not been any need for me to look at >>100MHz signals in a long time. I am not at all proficient with >>oscilloscopes and have never used a digital one. Last one I used had a >>round green screen :) which hints at how long ago that was... So flat(er) >>learning curve would be important for me. >> >>Are there people here using this brand? Are they any good for use in >>digital designs and, most importantly for me at this point, easy to learn? >> >>I guess, Rigol may not be the only ones making digital oscilloscopes these >>days. What other brands/models should I also look at? >> >>Thanks for your suggestions! > >I'll sell you a Tektronix 500MHz 1GSa/S TDS540 for $800 + shipping. :) Since DA took a pass i must ask, does it include probes? Option 1M?
From: JosephKK on 13 Dec 2009 12:58
On Tue, 08 Dec 2009 06:33:49 +0000, info_at_cabling-design_dot_com(a)foo.com (DA) wrote: >DA had written this in response to >http://www.electrondepot.com/electrodesign/A-good-digital-oscilloscope-442160-.htm > : > >DA wrote: > > >> Hi all, >> I think I'm going to try and treat myself to an oscilloscope this >> Christmas. > >Thank you for all your great suggestions, guys! I got some brand names >here, Tektronix I knew from years back, other names like Instek are new to >me. Rigol still looks like a great scope for light use. Although you never >know, maybe I'll like it so much that I'll use it to measure voltages :) >Anyways, it might just all come down to price vs. useability. Rigol is the >cheapest brand I could find (which is usually scary) but it seems to have >developed some following, so it looks like a good deal. I'm going to look >around some more but it does not look like there is any brand that's even >remotely close to Rigol's prices so I'm most likely going to get their 2CH >50MHz model. > >Thanks again! > Instek, Rigol, and Hameg are ODM for Agilent, Tek, and Phillips(?); not necessarily in that order. |