USB function generators?
in [Design]
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From: Joerg on 9 May 2010 09:27 Paul Keinanen wrote: > On Fri, 07 May 2010 16:17:18 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> Nico Coesel wrote: >>> Joerg <invalid(a)invalid.invalid> wrote: >>> >>>> Gents, >>>> >>>> Unless it rains on Sunday and I have some time I might just junk this >>>> dreaded Wavetek Model 23 generator. Looked around for USB-based >>>> generators and found a nice li'l scope/gen combo: >>>> >>>> http://www.allspectrum.com/store/product_info.php?products_id=2778 >>>> >>>> Not a lot of info, seems it has no galvanic isolation from the computer >>>> like some others <knuckles turning white ...>. However, unlike many >>>> others it does go down to 5 millihertz so can be used in machine, stress >>>> and vibration testing which I need to do at times. >>>> >>>> What do thee think? >>> USB isolators are probably not expensive. >>> >> In this case it would be a bit more challenging because the thing is >> also supplied via the USB jack. I could fix that, but ideally I'd like >> something I can plug in and it just works. > > Indeed, the USB isolator and a self powered USB hub would be quite > nasty. > Another challenge in many of my jobs is the EMI that some of these converters kick out. > Perhaps a miniature laptop with big batteries could be floated with > the test equipment, but the stray capacitances could cause problems. > > Doing measurements with the test system floating on the mains voltage > would also be dangerous. > In that respect I am quite brazen but I make sure nobody gets too close to my lab bench while this stuff is running :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 9 May 2010 09:34 miso(a)sushi.com wrote: > On May 8, 4:16 pm, n...(a)puntnl.niks (Nico Coesel) wrote: >> "m...(a)sushi.com" <m...(a)sushi.com> wrote: >>> On May 7, 2:13=A0pm, Joerg <inva...(a)invalid.invalid> wrote: >>>> Gents, >>>> Unless it rains on Sunday and I have some time I might just junk this >>>> dreaded Wavetek Model 23 generator. Looked around for USB-based >>>> generators and found a nice li'l scope/gen combo: >>>> http://www.allspectrum.com/store/product_info.php?products_id=3D2778 >>>> Not a lot of info, seems it has no galvanic isolation from the computer >>>> like some others <knuckles turning white ...>. However, unlike many >>>> others it does go down to 5 millihertz so can be used in machine, stress >>>> and vibration testing which I need to do at times. >>>> What do thee think? >>>> -- >>>> Regards, Joerg >>>> http://www.analogconsultants.com/ >>>> "gmail" domain blocked because of excessive spam. >>>> Use another domain or send PM. >>> USB is always a driver hassle. I try to buy USB devices that also work >>> in Linux, so if the company goes bust, you can at least run the box >>> under linux. >>> $300 would get you a nice function generator at a ham swap meet. My >>> PM5191 was $125 in a freakin' store (RA Surplus, now defunct) years >>> ago. You can't get much money for low bandwidth generators these days. >> Well... a good HP3314A still sells for a couple of hundred. More >> recent Agilent generators fetch even more. AFAIK those are USB and/or >> ethernet controllable. >> >> -- >> Failure does not prove something is impossible, failure simply >> indicates you are not using the right tools... >> nico(a)nctdevpuntnl (punt=.) >> -------------------------------------------------------------- > > The HP3314A has a control panel, so it's not like you are buying a > black box USB device from a Chinese company that won't exist in a few > years. Black boxes can become bricks if the drivers are history. ... How do drivers become history? With all my black boxes they came with the box. Ok, I do not change operating systems at every whim some guys in Redmond might publish. If a "new and improved" OS is not backwards compatible with my legacy stuff I won't buy, I'll stay with the old OS. > ... Think > about all the ISA controlled items that have become bricks. ISA GPIB > boards are valueable only for their trade in value with Nation > Instruments. Anybody need a scsi drive? Now ethernet is another story. > It doesn't need drivers. > Huh? You can buy plenty of brand new PCs with numerous ISA slots. Regular quality or industrial stuff. And I'd venture to say that you will find a similar selection 10 years from now. > I've seen the similar Fluke or Tek function generator that cuts out at > 11Mhz go for about $200. I think Joerg's issue is a lack of local > geeks. ;-) In the bay area, these items are very common on the used > market. Probably LA as well. > Yup, out here there's abosultely nothing going on of what you have in the Bay Area in terms of electronics stores. IOW, out here there are none left. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jamie on 9 May 2010 10:38 Joerg wrote: > Paul Keinanen wrote: > >> On Fri, 07 May 2010 16:17:18 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> Nico Coesel wrote: >>> >>>> Joerg <invalid(a)invalid.invalid> wrote: >>>> >>>>> Gents, >>>>> >>>>> Unless it rains on Sunday and I have some time I might just junk >>>>> this dreaded Wavetek Model 23 generator. Looked around for >>>>> USB-based generators and found a nice li'l scope/gen combo: >>>>> >>>>> http://www.allspectrum.com/store/product_info.php?products_id=2778 >>>>> >>>>> Not a lot of info, seems it has no galvanic isolation from the >>>>> computer like some others <knuckles turning white ...>. However, >>>>> unlike many others it does go down to 5 millihertz so can be used >>>>> in machine, stress and vibration testing which I need to do at times. >>>>> >>>>> What do thee think? >>>> >>>> USB isolators are probably not expensive. >>>> >>> In this case it would be a bit more challenging because the thing is >>> also supplied via the USB jack. I could fix that, but ideally I'd >>> like something I can plug in and it just works. >> >> >> Indeed, the USB isolator and a self powered USB hub would be quite >> nasty. >> > > Another challenge in many of my jobs is the EMI that some of these > converters kick out. Not using potted or toroidal coils in the buck area usually causes this and a few bypassers here and there. Nice EMI radiator using open coils :)
From: John Larkin on 9 May 2010 11:40 On Fri, 07 May 2010 14:13:49 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Gents, > >Unless it rains on Sunday It's raining here, headed slowly your way. Got leaks? Rain in May is unusual here. We had a very wet winter, lots of snowpack, long hot (indoor) showers in the forecast. I hope it's a trend. John
From: Joerg on 9 May 2010 12:19
Jamie wrote: > Joerg wrote: > >> Paul Keinanen wrote: >> >>> On Fri, 07 May 2010 16:17:18 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> Nico Coesel wrote: >>>> >>>>> Joerg <invalid(a)invalid.invalid> wrote: >>>>> >>>>>> Gents, >>>>>> >>>>>> Unless it rains on Sunday and I have some time I might just junk >>>>>> this dreaded Wavetek Model 23 generator. Looked around for >>>>>> USB-based generators and found a nice li'l scope/gen combo: >>>>>> >>>>>> http://www.allspectrum.com/store/product_info.php?products_id=2778 >>>>>> >>>>>> Not a lot of info, seems it has no galvanic isolation from the >>>>>> computer like some others <knuckles turning white ...>. However, >>>>>> unlike many others it does go down to 5 millihertz so can be used >>>>>> in machine, stress and vibration testing which I need to do at times. >>>>>> >>>>>> What do thee think? >>>>> >>>>> USB isolators are probably not expensive. >>>>> >>>> In this case it would be a bit more challenging because the thing is >>>> also supplied via the USB jack. I could fix that, but ideally I'd >>>> like something I can plug in and it just works. >>> >>> >>> Indeed, the USB isolator and a self powered USB hub would be quite >>> nasty. >>> >> >> Another challenge in many of my jobs is the EMI that some of these >> converters kick out. > > Not using potted or toroidal coils in the buck area usually causes this > and a few bypassers here and there. > > Nice EMI radiator using open coils :) > Potted or "shielded" inductors have a surprisingly large air gap, camouflaged by using a potting compound in "ferrite color". A guy from the German NG recently did a test. Soldered an LED to an inductor of same type, held it over the other ... and there was light :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |