On 03/22/2011 03:01 PM, RST Engineering wrote:> > About 5 years ago I did a design for a simple TRF receiver that used > small Xicon (Mouser) tunable coils in the 50-200 nanohenry range, size > 10 mm and 7 mm series. > > Now they've gone to a minimum of 5000 pieces per value and by my > calculations that will take me well into the next century at current > use rates. > > Anybody got a good source for small tunable coils, preferably > shielded?Digikey used to carry a slew of Toko coils, but I couldn't vouch for their current availability. If your volumes are _really_ low, you can probably still get coil forms from Amidon and roll your own. You'll have to hunt down Amidon, though -- they've changed hands since the last time I ordered, and I always have to search around to find their site. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
New 555 Spice Model
Started by ●March 18, 2011
Reply by ●March 22, 20112011-03-22
Reply by ●March 22, 20112011-03-22
"RST Engineering" <jweir43@gmail.com> wrote in message news:vp6io6lkrk67qvsbpvos6h6cg2dp9an0s2@4ax.com...> > About 5 years ago I did a design for a simple TRF receiver that used > small Xicon (Mouser) tunable coils in the 50-200 nanohenry range, size > 10 mm and 7 mm series. > > Now they've gone to a minimum of 5000 pieces per value and by my > calculations that will take me well into the next century at current > use rates. > > Anybody got a good source for small tunable coils, preferably > shielded? > > Thanks, > > Jim >Spectrum communications/Tony nailer in the UK has recently started having 10mm IFTs made in the far east, these are mainly aimed at the ham radio market but the available inductance ranges can be had in 1 off qty.
Reply by ●March 22, 20112011-03-22
On 03/22/2011 03:08 PM, Joerg wrote:> Tim Wescott wrote: >> On 03/22/2011 03:01 PM, RST Engineering wrote: >>> >>> About 5 years ago I did a design for a simple TRF receiver that used >>> small Xicon (Mouser) tunable coils in the 50-200 nanohenry range, size >>> 10 mm and 7 mm series. >>> >>> Now they've gone to a minimum of 5000 pieces per value and by my >>> calculations that will take me well into the next century at current >>> use rates. >>> >>> Anybody got a good source for small tunable coils, preferably >>> shielded? >> >> Digikey used to carry a slew of Toko coils, but I couldn't vouch for >> their current availability. >> >> If your volumes are _really_ low, you can probably still get coil forms >> from Amidon and roll your own. You'll have to hunt down Amidon, though >> -- they've changed hands since the last time I ordered, and I always >> have to search around to find their site. >> > > Easy: > > https://www.amidoncorp.com/ >Cool. Click on "Tunable Inductors" to get to the coil forms I was talking about. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
Reply by ●March 22, 20112011-03-22
Tim Wescott wrote:> On 03/22/2011 03:08 PM, Joerg wrote: >> Tim Wescott wrote: >>> On 03/22/2011 03:01 PM, RST Engineering wrote: >>>> >>>> About 5 years ago I did a design for a simple TRF receiver that used >>>> small Xicon (Mouser) tunable coils in the 50-200 nanohenry range, size >>>> 10 mm and 7 mm series. >>>> >>>> Now they've gone to a minimum of 5000 pieces per value and by my >>>> calculations that will take me well into the next century at current >>>> use rates. >>>> >>>> Anybody got a good source for small tunable coils, preferably >>>> shielded? >>> >>> Digikey used to carry a slew of Toko coils, but I couldn't vouch for >>> their current availability. >>> >>> If your volumes are _really_ low, you can probably still get coil forms >>> from Amidon and roll your own. You'll have to hunt down Amidon, though >>> -- they've changed hands since the last time I ordered, and I always >>> have to search around to find their site. >>> >> >> Easy: >> >> https://www.amidoncorp.com/ >> > Cool. Click on "Tunable Inductors" to get to the coil forms I was > talking about. >You can also get ready-wound ones from Digikey. Around a buck a pop AFAIR. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Reply by ●March 22, 20112011-03-22
"RST Engineering" <jweir43@gmail.com> wrote in message news:vp6io6lkrk67qvsbpvos6h6cg2dp9an0s2@4ax.com...> About 5 years ago I did a design for a simple TRF receiver that used > small Xicon (Mouser) tunable coils in the 50-200 nanohenry range, size > 10 mm and 7 mm series. > > Now they've gone to a minimum of 5000 pieces per value and by my > calculations that will take me well into the next century at current > use rates. > > Anybody got a good source for small tunable coils, preferably > shielded?We use a bazillion of these Coilcraft ones: http://coilcraft.com/ldtune.cfm . I don't know our order quantities, but I'm sure it's not 5000 at a shot -- possibly 500, although probably more like 100. Purchasing has never said they're hard to get, AFAIK. ---Joel
Reply by ●March 22, 20112011-03-22
On Tue, 22 Mar 2011 17:01:45 -0500, John Fields <jfields@austininstruments.com> wrote:>On Fri, 18 Mar 2011 22:46:48 -0400, Bitrex ><bitrex@de.lete.earthlink.net> wrote: > >>On 3/18/2011 7:13 PM, Jim Thompson wrote: >>> Got annoyed at the flaky 555 models that are out there, so I rolled my >>> own... >>> >>> http://www.analog-innovations.com/SED/MyLMC555.zip >>> >>> Based on old AMI 20V CMOS device models, mostly form/fit/function with >>> CMOS, but some behavioral on the front-end where it doesn't matter. >>> >>> Optimized and fitted to National LMC555 at 5V operation. It'll work >>> at other voltages but may sink/source more or less than spec at other >>> voltages because of ancient 5u devices :-) >>> >>> Try it out and let me know. >>> >>> ...Jim Thompson >> >>Hi Jim, >> >>Thanks for taking the time to create this model. I was doing some >>experimenting with it and comparing it to the standard bipolar 555 >>model, and noticed that the CMOS model seems to have significantly >>greater shoot-through current than the bipolar model. I haven't used a >>CMOS 555 or measured those currents "in real life", so I'm curious if >>that is a real difference, or perhaps the bipolar 555 models don't model >>it effectively? > >--- >Notice that the shoot-through current for an ICM7555, in real life, as >indicated on page 6 of: > >http://datasheets.maxim-ic.com/en/ds/ICM7555-ICM7556.pdf > >is very small compared to that from the bipolar 555, so there's either >something wrong with Jim's model, or you're making an error of some >kind. > >--- >JFI sized my CMOS devices based on source and sink current of the output at VCC=+5V for the _LMC555_ chip... Intersil datasheet was used only for structural ideas. I simulate 7-8mA "shoot-thru" depending on direction of transition. Which, for CMOS with considerable source sink capability, seems pretty normal to me. Width at the 50% point of overlap current is 8.5ns, TF/TR at output ~ 7.3ns What does "...significantly greater shoot-through current than the bipolar model" mean? ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Remember: Once you go over the hill, you pick up speed
Reply by ●March 22, 20112011-03-22
On Tue, 22 Mar 2011 15:01:11 -0700, RST Engineering <jweir43@gmail.com> wrote:> >About 5 years ago I did a design for a simple TRF receiver that used >small Xicon (Mouser) tunable coils in the 50-200 nanohenry range, size >10 mm and 7 mm series. > >Now they've gone to a minimum of 5000 pieces per value and by my >calculations that will take me well into the next century at current >use rates. > >Anybody got a good source for small tunable coils, preferably >shielded? > >Thanks, > >JimAsk for samples! John
Reply by ●March 24, 20112011-03-24
On 3/22/2011 7:01 PM, Jim Thompson wrote:> On Tue, 22 Mar 2011 17:01:45 -0500, John Fields > <jfields@austininstruments.com> wrote: > >> On Fri, 18 Mar 2011 22:46:48 -0400, Bitrex >> <bitrex@de.lete.earthlink.net> wrote: >> >>> On 3/18/2011 7:13 PM, Jim Thompson wrote: >>>> Got annoyed at the flaky 555 models that are out there, so I rolled my >>>> own... >>>> >>>> http://www.analog-innovations.com/SED/MyLMC555.zip >>>> >>>> Based on old AMI 20V CMOS device models, mostly form/fit/function with >>>> CMOS, but some behavioral on the front-end where it doesn't matter. >>>> >>>> Optimized and fitted to National LMC555 at 5V operation. It'll work >>>> at other voltages but may sink/source more or less than spec at other >>>> voltages because of ancient 5u devices :-) >>>> >>>> Try it out and let me know. >>>> >>>> ...Jim Thompson >>> >>> Hi Jim, >>> >>> Thanks for taking the time to create this model. I was doing some >>> experimenting with it and comparing it to the standard bipolar 555 >>> model, and noticed that the CMOS model seems to have significantly >>> greater shoot-through current than the bipolar model. I haven't used a >>> CMOS 555 or measured those currents "in real life", so I'm curious if >>> that is a real difference, or perhaps the bipolar 555 models don't model >>> it effectively? >> >> --- >> Notice that the shoot-through current for an ICM7555, in real life, as >> indicated on page 6 of: >> >> http://datasheets.maxim-ic.com/en/ds/ICM7555-ICM7556.pdf >> >> is very small compared to that from the bipolar 555, so there's either >> something wrong with Jim's model, or you're making an error of some >> kind. >> >> --- >> JF > > I sized my CMOS devices based on source and sink current of the output > at VCC=+5V for the _LMC555_ chip... Intersil datasheet was used only > for structural ideas. > > I simulate 7-8mA "shoot-thru" depending on direction of transition. > Which, for CMOS with considerable source sink capability, seems pretty > normal to me. Width at the 50% point of overlap current is 8.5ns, > TF/TR at output ~ 7.3ns > > What does "...significantly greater shoot-through current than the > bipolar model" mean? > > ...Jim ThompsonSorry for the delay in my reply, I didn't realize the thread was still active. Here's what I get using LTSpice with the test circuit: http://i227.photobucket.com/albums/dd240/bitrex2007/555.jpg The pulses appear to be about 100 ns wide. It probably is really better than the bipolar 555, because looking at the graph on the Maxim datasheet I don't believe the bipolar 555 model included with LTSpice is modeling the supply spikes accurately.
Reply by ●March 24, 20112011-03-24
On 3/24/2011 12:33 PM, Bitrex wrote:> On 3/22/2011 7:01 PM, Jim Thompson wrote: >> On Tue, 22 Mar 2011 17:01:45 -0500, John Fields >> <jfields@austininstruments.com> wrote: >> >>> On Fri, 18 Mar 2011 22:46:48 -0400, Bitrex >>> <bitrex@de.lete.earthlink.net> wrote: >>> >>>> On 3/18/2011 7:13 PM, Jim Thompson wrote: >>>>> Got annoyed at the flaky 555 models that are out there, so I rolled my >>>>> own... >>>>> >>>>> http://www.analog-innovations.com/SED/MyLMC555.zip >>>>> >>>>> Based on old AMI 20V CMOS device models, mostly form/fit/function with >>>>> CMOS, but some behavioral on the front-end where it doesn't matter. >>>>> >>>>> Optimized and fitted to National LMC555 at 5V operation. It'll work >>>>> at other voltages but may sink/source more or less than spec at other >>>>> voltages because of ancient 5u devices :-) >>>>> >>>>> Try it out and let me know. >>>>> >>>>> ...Jim Thompson >>>> >>>> Hi Jim, >>>> >>>> Thanks for taking the time to create this model. I was doing some >>>> experimenting with it and comparing it to the standard bipolar 555 >>>> model, and noticed that the CMOS model seems to have significantly >>>> greater shoot-through current than the bipolar model. I haven't used a >>>> CMOS 555 or measured those currents "in real life", so I'm curious if >>>> that is a real difference, or perhaps the bipolar 555 models don't >>>> model >>>> it effectively? >>> >>> --- >>> Notice that the shoot-through current for an ICM7555, in real life, as >>> indicated on page 6 of: >>> >>> http://datasheets.maxim-ic.com/en/ds/ICM7555-ICM7556.pdf >>> >>> is very small compared to that from the bipolar 555, so there's either >>> something wrong with Jim's model, or you're making an error of some >>> kind. >>> >>> --- >>> JF >> >> I sized my CMOS devices based on source and sink current of the output >> at VCC=+5V for the _LMC555_ chip... Intersil datasheet was used only >> for structural ideas. >> >> I simulate 7-8mA "shoot-thru" depending on direction of transition. >> Which, for CMOS with considerable source sink capability, seems pretty >> normal to me. Width at the 50% point of overlap current is 8.5ns, >> TF/TR at output ~ 7.3ns >> >> What does "...significantly greater shoot-through current than the >> bipolar model" mean? >> >> ...Jim Thompson > > Sorry for the delay in my reply, I didn't realize the thread was still > active. Here's what I get using LTSpice with the test circuit: > > http://i227.photobucket.com/albums/dd240/bitrex2007/555.jpg > > The pulses appear to be about 100 ns wide. It probably is really better > than the bipolar 555, because looking at the graph on the Maxim > datasheet I don't believe the bipolar 555 model included with LTSpice is > modeling the supply spikes accurately.My mistake, I think the pulses are shorter than that. It's a little tricky measuring them in LTSpice.
Reply by ●March 24, 20112011-03-24
On Thu, 24 Mar 2011 12:33:07 -0400, Bitrex <bitrex@de.lete.earthlink.net> wrote: . . .>I don't believe the bipolar 555 model included with LTSpice is >modeling the supply spikes accurately.--- Here's the circuit I'm using to test Linear's NE555 model: Version 4 SHEET 1 880 748 WIRE 224 192 -128 192 WIRE 544 192 448 192 WIRE -128 256 -128 192 WIRE -80 256 -128 256 WIRE 32 256 0 256 WIRE 64 256 32 256 WIRE 224 256 144 256 WIRE 512 256 448 256 WIRE 32 320 32 256 WIRE 176 320 32 320 WIRE 224 320 176 320 WIRE 608 320 448 320 WIRE 480 384 448 384 WIRE 608 416 608 320 WIRE 176 480 176 320 WIRE 512 480 512 256 WIRE 512 480 176 480 WIRE 544 496 544 192 WIRE -128 512 -128 256 WIRE 480 512 480 384 WIRE 480 512 -128 512 WIRE -128 528 -128 512 WIRE 176 544 176 480 WIRE -128 624 -128 608 WIRE 176 624 176 608 WIRE 176 624 -128 624 WIRE 544 624 544 576 WIRE 544 624 176 624 WIRE 608 624 608 496 WIRE 608 624 544 624 WIRE -128 688 -128 624 FLAG -128 688 0 SYMBOL Misc\\NE555 336 288 M0 SYMATTR InstName U1 SYMBOL voltage -128 512 M0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL res -96 240 M90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 58 VTop 0 SYMATTR InstName R1 SYMATTR Value 40k SYMBOL res 48 240 M90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R2 SYMATTR Value 19.8k SYMBOL res 624 400 M0 WINDOW 0 -45 40 Left 0 WINDOW 3 -59 71 Left 0 SYMATTR InstName R3 SYMATTR Value 1000 SYMBOL cap 192 544 M0 WINDOW 0 -33 32 Left 0 WINDOW 3 -39 58 Left 0 SYMATTR InstName C1 SYMATTR Value 1e-7 SYMBOL res 528 480 R0 SYMATTR InstName R4 SYMATTR Value 1 TEXT 88 656 Right 0 !.tran .1 startup uic TEXT 456 176 Left 0 ;1 TEXT 456 240 Left 0 ;2 TEXT 456 304 Left 0 ;3 TEXT 456 360 Left 0 ;4 TEXT 200 368 Left 0 ;5 TEXT 200 304 Left 0 ;6 TEXT 200 240 Left 0 ;7 TEXT 200 176 Left 0 ;8 I've just posted a query to: http://groups.yahoo.com/group/LTspice/ for clarification re. the accuracy of the model, and I'll post what comes back as soon as I get it. Maybe Helmut will post here first. -- JF
