blast from past
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From: ehsjr on 26 Jul 2010 00:13 John Larkin wrote: > I spent most of the day building this. > > ftp://jjlarkin.lmi.net/V220_Test_Front.jpg > What did you use for the labels? Ed > ftp://jjlarkin.lmi.net/V220_Test_Back.jpg > > which is a fixture to help test/cal a new VME module. It's powered by > a 48-volt wall wart. Those old-fashioned teevee type terminal strips, > and rotary switches, are pretty cool. This really deserves a more > macho knob, but that's all I could find around the place without > stealing one from something in the antique collection. > > The thing it connects to has 13 ARM processors and one FPGA on the > board. Time warp. > > ftp://jjlarkin.lmi.net/V220_top.jpg > > John > >
From: Fred Bartoli on 26 Jul 2010 10:24 Joerg a �crit : > John Larkin wrote: >> I spent most of the day building this. >> >> ftp://jjlarkin.lmi.net/V220_Test_Front.jpg >> >> ftp://jjlarkin.lmi.net/V220_Test_Back.jpg >> >> which is a fixture to help test/cal a new VME module. It's powered by >> a 48-volt wall wart. Those old-fashioned teevee type terminal strips, >> and rotary switches, are pretty cool. This really deserves a more >> macho knob, but that's all I could find around the place without >> stealing one from something in the antique collection. >> >> The thing it connects to has 13 ARM processors and one FPGA on the >> board. Time warp. >> >> ftp://jjlarkin.lmi.net/V220_top.jpg >> > > Do I see three tantalums on the bottom right? Oh-oh ... :-) > Hmmm, he said "Blast from the past" ;-) -- Thanks, Fred.
From: Joerg on 26 Jul 2010 10:33 John Larkin wrote: > On Sun, 25 Jul 2010 17:19:23 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Sun, 25 Jul 2010 15:08:52 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Sun, 25 Jul 2010 14:39:46 -0700, Joerg <invalid(a)invalid.invalid> >>>>> wrote: >>>>> >>>>>> John Larkin wrote: >>>>>>> I spent most of the day building this. >>>>>>> >>>>>>> ftp://jjlarkin.lmi.net/V220_Test_Front.jpg >>>>>>> >>>>>>> ftp://jjlarkin.lmi.net/V220_Test_Back.jpg >>>>>>> >>>>>>> which is a fixture to help test/cal a new VME module. It's powered by >>>>>>> a 48-volt wall wart. Those old-fashioned teevee type terminal strips, >>>>>>> and rotary switches, are pretty cool. This really deserves a more >>>>>>> macho knob, but that's all I could find around the place without >>>>>>> stealing one from something in the antique collection. >>>>>>> >>>>>>> The thing it connects to has 13 ARM processors and one FPGA on the >>>>>>> board. Time warp. >>>>>>> >>>>>>> ftp://jjlarkin.lmi.net/V220_top.jpg >>>>>>> >>>>>> Do I see three tantalums on the bottom right? Oh-oh ... :-) >>>>> Yes. LM1117's like tantalums on their outputs; the ESR is just right, >>>>> and will hold up at -20C. They are all 22u, 10v, 11 cents each, on the >>>>> outputs of 3.3, 2.5, and 1.25 volt regulators. That should be safe. >>>>> >>>>> Why make rules if you can't break them once in a while? >>>>> >>>>> The 1.25 is FPGA core voltage; that's an LM1117 with its adj pin >>>>> grounded. The 2.5 is FPGA VCCaux, another LM1117 with its adj pin tied >>>>> to the 1.25 rail. I would happily show the programming resistor >>>>> values, except there aren't any. >>>>> >>>> Well, if you have good experience with the LM1117 maybe it works. I just >>>> don't trust LDOs anymore, too much grief. Only one was my own design and >>>> only because the client absolutely insisted on a particular LDO to be >>>> used. Then, sure enough ... *PHOOF* ... *POP* >>> The 1117 is basically an LM317 architecture with a little less >>> dropout. The final pass transistor is an NPN, so the open-loop output >>> impedance is relatively low. They are rugged, cheap, and stable if you >>> put a tantalum or aluminum on their output. >>> >> At least they state a range from 0.3ohms to 22ohms for this one instead >> of some obscure graph. I'd still prefer ceramics plus resistor but >> that's more real estate which in your case often matters a lot. >> >> >>> I use them as power amps, too, driving the adj pin with an opamp. >>> >> I have done that with the LM317, using it as a modulator. It doesn't get >> much cheaper than that because the transmit stage needed a regulator >> anyhow. So it was essentially a free modulator. > > And you get thermal limiting and current limiting for free. > But it doesn't dispense Guinness :-) I was amazed how many Irish pubs there are in Mountain View. Wish I could have come up and see you but we were on a tightly scheduled round-trip through the west. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 26 Jul 2010 10:33 Fred Bartoli wrote: > Joerg a �crit : >> John Larkin wrote: >>> I spent most of the day building this. >>> >>> ftp://jjlarkin.lmi.net/V220_Test_Front.jpg >>> >>> ftp://jjlarkin.lmi.net/V220_Test_Back.jpg >>> >>> which is a fixture to help test/cal a new VME module. It's powered by >>> a 48-volt wall wart. Those old-fashioned teevee type terminal strips, >>> and rotary switches, are pretty cool. This really deserves a more >>> macho knob, but that's all I could find around the place without >>> stealing one from something in the antique collection. >>> >>> The thing it connects to has 13 ARM processors and one FPGA on the >>> board. Time warp. >>> >>> ftp://jjlarkin.lmi.net/V220_top.jpg >>> >> >> Do I see three tantalums on the bottom right? Oh-oh ... :-) >> > > Hmmm, he said "Blast from the past" ;-) > Good one :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: John Larkin on 26 Jul 2010 11:15
On Mon, 26 Jul 2010 07:33:06 -0700, Joerg <invalid(a)invalid.invalid> wrote: >John Larkin wrote: >> On Sun, 25 Jul 2010 17:19:23 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Sun, 25 Jul 2010 15:08:52 -0700, Joerg <invalid(a)invalid.invalid> >>>> wrote: >>>> >>>>> John Larkin wrote: >>>>>> On Sun, 25 Jul 2010 14:39:46 -0700, Joerg <invalid(a)invalid.invalid> >>>>>> wrote: >>>>>> >>>>>>> John Larkin wrote: >>>>>>>> I spent most of the day building this. >>>>>>>> >>>>>>>> ftp://jjlarkin.lmi.net/V220_Test_Front.jpg >>>>>>>> >>>>>>>> ftp://jjlarkin.lmi.net/V220_Test_Back.jpg >>>>>>>> >>>>>>>> which is a fixture to help test/cal a new VME module. It's powered by >>>>>>>> a 48-volt wall wart. Those old-fashioned teevee type terminal strips, >>>>>>>> and rotary switches, are pretty cool. This really deserves a more >>>>>>>> macho knob, but that's all I could find around the place without >>>>>>>> stealing one from something in the antique collection. >>>>>>>> >>>>>>>> The thing it connects to has 13 ARM processors and one FPGA on the >>>>>>>> board. Time warp. >>>>>>>> >>>>>>>> ftp://jjlarkin.lmi.net/V220_top.jpg >>>>>>>> >>>>>>> Do I see three tantalums on the bottom right? Oh-oh ... :-) >>>>>> Yes. LM1117's like tantalums on their outputs; the ESR is just right, >>>>>> and will hold up at -20C. They are all 22u, 10v, 11 cents each, on the >>>>>> outputs of 3.3, 2.5, and 1.25 volt regulators. That should be safe. >>>>>> >>>>>> Why make rules if you can't break them once in a while? >>>>>> >>>>>> The 1.25 is FPGA core voltage; that's an LM1117 with its adj pin >>>>>> grounded. The 2.5 is FPGA VCCaux, another LM1117 with its adj pin tied >>>>>> to the 1.25 rail. I would happily show the programming resistor >>>>>> values, except there aren't any. >>>>>> >>>>> Well, if you have good experience with the LM1117 maybe it works. I just >>>>> don't trust LDOs anymore, too much grief. Only one was my own design and >>>>> only because the client absolutely insisted on a particular LDO to be >>>>> used. Then, sure enough ... *PHOOF* ... *POP* >>>> The 1117 is basically an LM317 architecture with a little less >>>> dropout. The final pass transistor is an NPN, so the open-loop output >>>> impedance is relatively low. They are rugged, cheap, and stable if you >>>> put a tantalum or aluminum on their output. >>>> >>> At least they state a range from 0.3ohms to 22ohms for this one instead >>> of some obscure graph. I'd still prefer ceramics plus resistor but >>> that's more real estate which in your case often matters a lot. >>> >>> >>>> I use them as power amps, too, driving the adj pin with an opamp. >>>> >>> I have done that with the LM317, using it as a modulator. It doesn't get >>> much cheaper than that because the transmit stage needed a regulator >>> anyhow. So it was essentially a free modulator. >> >> And you get thermal limiting and current limiting for free. >> > >But it doesn't dispense Guinness :-) > >I was amazed how many Irish pubs there are in Mountain View. Wish I >could have come up and see you but we were on a tightly scheduled >round-trip through the west. If you go to a Giants game at PacBell Park, you can actually get a hand-made draft Black&Tan for the price of a regular beer. Of course, that's $9. Drop in anytime. John |