On Monday, May 25, 2020 at 7:52:38 PM UTC-4, Cydrome Leader wrote:> piglet <erichpwagner@hotmail.com> wrote: > > On 25/05/2020 5:28 am, Bill Sloman wrote: > >> > >> Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. > >> > >> You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. > >> > > > > Yes, see: > > > > <www.crystalonics.com/dualEmitter.php> > > > > Were used as low-offset switches in chopper amps circa early-mid 1960s, > > long since obsoleted by fet switches. > > > > piglet > > Ha. The part numbers are a riot- like 3N62. It's nice when part numbers > follow standards that convey useful information.3N was the JEDIC prefix for FETs, so it was a standard that was widely ignored..
why do they do this?
Started by ●May 18, 2020
Reply by ●May 26, 20202020-05-26
Reply by ●May 26, 20202020-05-26
On 2020-05-26 01:37, Michael Terrell wrote:> On Monday, May 25, 2020 at 7:52:38 PM UTC-4, Cydrome Leader wrote: >> piglet <erichpwagner@hotmail.com> wrote: >>> On 25/05/2020 5:28 am, Bill Sloman wrote: >>>> >>>> Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. >>>> >>>> You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. >>>> >>> >>> Yes, see: >>> >>> <www.crystalonics.com/dualEmitter.php> >>> >>> Were used as low-offset switches in chopper amps circa early-mid 1960s, >>> long since obsoleted by fet switches. >>> >>> piglet >> >> Ha. The part numbers are a riot- like 3N62. It's nice when part numbers >> follow standards that convey useful information. > > > 3N was the JEDIC prefix for FETs, so it was a standard that was widely ignored.. >I used to use 3N201 dual-gate MOSFETs for slowish samplers. Their charge injection was really really low. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●May 26, 20202020-05-26
On 2020-05-25 19:49, Cydrome Leader wrote:> Bill Sloman <bill.sloman@ieee.org> wrote: >> On Monday, May 25, 2020 at 9:16:08 AM UTC+10, Cydrome Leader wrote: >>> Klaus Kragelund <klauskvik@hotmail.com> wrote: >>>> On Saturday, May 23, 2020 at 9:32:38 AM UTC+2, Cydrome Leader wrote: >>>>> Klaus Kragelund <klauskvik@hotmail.com> wrote: >>>>>> On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: >>>>>>> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs >>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>> >>>>>>>> On 2020-05-21 13:38, John Larkin wrote: >>>>>>>>> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs >>>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>>>> >>>>>>>>>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: >>>>>>>>>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: >>>>>>>>>>> >>>>>>>>>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: >>>>>>>>>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), >>>>>>>>>>>>> bloggs.fredbloggs.fred@gmail.com wrote: >>>>>>>>>>>>> >>>>>>>>>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: >>>>>>>>>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias >>>>>>>>>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> It's an ST1L08. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> So why is the data sheet file en.DM00123507.pdf ? >>>>>>>>>>>>>> >>>>>>>>>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. >>>>>>>>>>>>> >>>>>>>>>>>>> Lying? It's all over the data sheet. It's how they get the millivolts >>>>>>>>>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp >>>>>>>>>>>>> from some higher voltage and over-drive an nfet follower down to >>>>>>>>>>>>> milliohms of Rds-on. >>>>>>>>>>>>> >>>>>>>>>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. >>>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA >>>>>>>>>>>>> would be 0.24 watts dissipated. Actually, I don't need that much >>>>>>>>>>>>> current to run a couple DRAM chips. >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 >>>>>>>>>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV >>>>>>>>>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V >>>>>>>>>>>> with 3% tolerance. As usual with products originating in the >>>>>>>>>>>> East, the datasheet is rather sparse about details, but I've used >>>>>>>>>>>> them and they do what I want. >>>>>>>>>>> >>>>>>>>>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. >>>>>>>>>>> >>>>>>>>>>> We need so many goofy voltages that we usually buy adjustable >>>>>>>>>>> regulators for stock. The board that I'm doing now has a 24-channel >>>>>>>>>>> analog mux to BIST the power supplies, using the dreadful Xilinx >>>>>>>>>>> 1-volt XADC that's inside their FPGAs. Free and worth it. >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>>> You sure are in a bad mood lately. >>>>>>>>>>>>> >>>>>>>>>>>> I've noticed that lately with some regulars here, including a few >>>>>>>>>>>> who normally exhibit decent manners. >>>>>>>>>>> >>>>>>>>>>> Well, some never show any sign of manners. They are repulsive but >>>>>>>>>>> you've got to feel sorry for them, stuck being around themselves all >>>>>>>>>>> day. >>>>>>>>>>> >>>>>>>>>>> There's a basically perfect -1 correlation between being obnoxious and >>>>>>>>>>> designing electronics. >>>>>>>>>> >>>>>>>>>> Well, now that Jim Thompson is apparently no longer with us. :( >>>>>>>>>> >>>>>>>>>> He was a bit of a statistical outlier. >>>>>>>>> >>>>>>>>> He was crabby and dismissive of people not as smart as he was, and >>>>>>>>> hostile to people that might have been smarter, but he was >>>>>>>>> occasionally helpful, and had a sense of humor, and was very brave at >>>>>>>>> the end. >>>>>>>>> >>>>>>>> >>>>>>>> When he wasn't busy accusing peoples' wives of immoral behaviour, >>>>>>>> threatening folks with lawsuits or bodily harm, or siccing the FBI on >>>>>>>> some deserving individuals. ;) >>>>>>> >>>>>>> Gosh, nobody's perfect. >>>>>>> >>>>>>>> >>>>>>>> He was probably nice enough in person--we collaborated a couple of times >>>>>>>> but never met in person or even talked on the phone together. >>>>>>>> >>>>>>>> I agree that he had guts and seems to have died very well. >>>>>>> >>>>>>> I used a version of his clever CD ignition (without his permission) as >>>>>>> a gain-switched laser driver. Nice circuit. >>>>>>> >>>>>> I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more >>>>>> >>>>>> He did an ASIC gatedriver design for us, nice design, cheap like we like it >>>>>> >>>>>> Suddenly we did not hear from him again, so another ASIC designer took over at that point >>>>>> >>>>>> He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip >>>>>> >>>>>> Cheers >>>>>> >>>>>> Klaus >>>>> >>>>> Got to ask here, if I didn't years ago. How much different in behavior are >>>>> analog circuits layed out with discrete components from the final IC >>>>> itself? Let's talk pre computer simulations. For example, microwave and RF >>>>> boards are constructed different from audio circuit boards, but if you >>>>> look at a schematic, it's just a bunch of discretes wired together. >>>> >>>> It can be very simelar >>>> >>>> In our case, to keep NRE low, we needed to use almost only predefined blocks. When you team up with a fab, they supply all datasheets and simulation models for standard blocks. So, opamps, comparators, digital blocks, voltage references, PWM circuits and individual transistors >>>> >>>> The blocks are proven in the technology and simulation vs real life is 100% spot on. The tools are very expensive, but they model the chip to every detail. Thus, experienced ASIC designers never need to do new revisions. >>>> >>>> If you wander off, and do custom blocks, it gets a lot more expensive >>>> >>>> So you if you find a discrete opamp that matches your ASIC block, so can do proof of concept in discrete design >>>> If not, simulations is the way forward >>>> >>>> And by the way, prototypes with MOSIS is very cheap, you just need to wait a loooooong time from design to the first chips comes in >>>> >>>> >>>> Cheers >>>> >>>> Klaus >>> >>> Hmm. What about equivalent, full sized components? >>> >>> Take the example the 74LS00 nand gate, TI has a schematic >>> >>> https://html.alldatasheet.com/html-pdf/27361/TI/74LS00N/73/3/74LS00N.html >>> >>> Are there equivalent transistors and diodes used in that schematic I can >>> run out and buy, to make an as close to 100% electrically compatible, drop >>> in replacement? >>> >>> I'm not even sure what the first transitor is with A and B inputs is even >>> called. What is it? >> >> Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. >> >> You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. > > A very odd device. Are there other weird semiconductors like that? >You can make one by using a monolithically matched pair such as half of a MAT-14 and connecting them base-to-base and collector-to-collector. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●May 26, 20202020-05-26
On Tuesday, May 26, 2020 at 8:05:49 AM UTC-4, Phil Hobbs wrote:> On 2020-05-26 01:37, Michael Terrell wrote: > > On Monday, May 25, 2020 at 7:52:38 PM UTC-4, Cydrome Leader wrote: > >> piglet <erichpwagner@hotmail.com> wrote: > >>> On 25/05/2020 5:28 am, Bill Sloman wrote: > >>>> > >>>> Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. > >>>> > >>>> You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. > >>>> > >>> > >>> Yes, see: > >>> > >>> <www.crystalonics.com/dualEmitter.php> > >>> > >>> Were used as low-offset switches in chopper amps circa early-mid 1960s, > >>> long since obsoleted by fet switches. > >>> > >>> piglet > >> > >> Ha. The part numbers are a riot- like 3N62. It's nice when part numbers > >> follow standards that convey useful information. > > > > > > 3N was the JEDIC prefix for FETs, so it was a standard that was widely ignored.. > > > I used to use 3N201 dual-gate MOSFETs for slowish samplers. Their > charge injection was really really low.The 3N128 was popular in Amateur Radio projects in the '70s along with RCA's 40673 that was used in TV tuners and garage door openers. They used to cost me 36 cents, from the Linear corporation that built the openers. I bought them 25 at a time, and often ran out before more were available. These were very sensitive receivers, and with careful alignment many would operate a door from three blocks away. That was handy for fire stations. They could start the doors to open and have them open enough that they didn't have to wait to pull off the road when they returned after a fire run. the 406743 turn up in small batches from time to time, but they aren't worth $20 each.
Reply by ●May 26, 20202020-05-26
There's a nice radio museum finder, some of you might have already visited. I suspect there could be a lot of contributors from this group. https://www.radiomuseum.org/museum/List_of_museums_science_technical_radio_finder_Museumsliste.html I was more into CMOS logic when it first came out but using it for analog applications such as buffered inverters with feedback. But my favourite little CMOS design back then was a converting a 10MHz OCXO into a Sawtooth with bipolars then and using the analog transmission gates as a S&H mixer using a telemetry subcarrier signal derived from a similar OCXO flying in a Black Brandt VI. The received signal was limited and I took the derivative to trigger the S&H CMOS switching 10MHz Sawtooth to get a low-cost Doppler ranging system, to replace the costly TRACS system up in Churchill, Mb. This was a rocket research station operated by NRC and used by researchers around the world including NASA and my 1st job at Bristol Aerospace Ltd in Winnipeg. (now Magellan)
Reply by ●May 26, 20202020-05-26
On 2020-05-26 09:01, Michael Terrell wrote:> On Tuesday, May 26, 2020 at 8:05:49 AM UTC-4, Phil Hobbs wrote: >> On 2020-05-26 01:37, Michael Terrell wrote: >>> On Monday, May 25, 2020 at 7:52:38 PM UTC-4, Cydrome Leader wrote: >>>> piglet <erichpwagner@hotmail.com> wrote: >>>>> On 25/05/2020 5:28 am, Bill Sloman wrote: >>>>>> >>>>>> Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. >>>>>> >>>>>> You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. >>>>>> >>>>> >>>>> Yes, see: >>>>> >>>>> <www.crystalonics.com/dualEmitter.php> >>>>> >>>>> Were used as low-offset switches in chopper amps circa early-mid 1960s, >>>>> long since obsoleted by fet switches. >>>>> >>>>> piglet >>>> >>>> Ha. The part numbers are a riot- like 3N62. It's nice when part numbers >>>> follow standards that convey useful information. >>> >>> >>> 3N was the JEDIC prefix for FETs, so it was a standard that was widely ignored.. >>> >> I used to use 3N201 dual-gate MOSFETs for slowish samplers. Their >> charge injection was really really low. > > > The 3N128 was popular in Amateur Radio projects in the '70s along with RCA's 40673 that was used in TV tuners and garage door openers. They used to cost me 36 cents, from the Linear corporation that built the openers. I bought them 25 at a time, and often ran out before more were available. These were very sensitive receivers, and with careful alignment many would operate a door from three blocks away. That was handy for fire stations. They could start the doors to open and have them open enough that they didn't have to wait to pull off the road when they returned after a fire run. the 406743 turn up in small batches from time to time, but they aren't worth $20 each.You can do the equivalent with a built-up cascode anyway. My very favourite dual-gate part was the Motorola MRF966 GaAs FET. You just connected gate 2 to the source, and, presto, an almost perfectly unilateral amplifier. I used to get > 70 dB isolation up to above 100 MHz with one stage. I used to use them connected directly to coax as cheapo FET probes--the pointy leads of the Macro-X package were perfect for that. I still have a couple of dozen, but haven't used one in ages. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●May 26, 20202020-05-26
On Mon, 25 May 2020 23:49:19 +0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:>Bill Sloman <bill.sloman@ieee.org> wrote: >> On Monday, May 25, 2020 at 9:16:08 AM UTC+10, Cydrome Leader wrote: >>> Klaus Kragelund <klauskvik@hotmail.com> wrote: >>> > On Saturday, May 23, 2020 at 9:32:38 AM UTC+2, Cydrome Leader wrote: >>> >> Klaus Kragelund <klauskvik@hotmail.com> wrote: >>> >> > On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: >>> >> >> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs >>> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >> >> >>> >> >> >On 2020-05-21 13:38, John Larkin wrote: >>> >> >> >> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs >>> >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >> >> >> >>> >> >> >>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: >>> >> >> >>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: >>> >> >> >>>> >>> >> >> >>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: >>> >> >> >>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), >>> >> >> >>>>>> bloggs.fredbloggs.fred@gmail.com wrote: >>> >> >> >>>>>> >>> >> >> >>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: >>> >> >> >>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias >>> >> >> >>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. >>> >> >> >>>>>>>> >>> >> >> >>>>>>>> It's an ST1L08. >>> >> >> >>>>>>>> >>> >> >> >>>>>>>> So why is the data sheet file en.DM00123507.pdf ? >>> >> >> >>>>>>> >>> >> >> >>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. >>> >> >> >>>>>> >>> >> >> >>>>>> Lying? It's all over the data sheet. It's how they get the millivolts >>> >> >> >>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp >>> >> >> >>>>>> from some higher voltage and over-drive an nfet follower down to >>> >> >> >>>>>> milliohms of Rds-on. >>> >> >> >>>>>> >>> >> >> >>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. >>> >> >> >>>>>>> >>> >> >> >>>>>> >>> >> >> >>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA >>> >> >> >>>>>> would be 0.24 watts dissipated. Actually, I don't need that much >>> >> >> >>>>>> current to run a couple DRAM chips. >>> >> >> >>>>>> >>> >> >> >>>>> >>> >> >> >>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 >>> >> >> >>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV >>> >> >> >>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V >>> >> >> >>>>> with 3% tolerance. As usual with products originating in the >>> >> >> >>>>> East, the datasheet is rather sparse about details, but I've used >>> >> >> >>>>> them and they do what I want. >>> >> >> >>>> >>> >> >> >>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. >>> >> >> >>>> >>> >> >> >>>> We need so many goofy voltages that we usually buy adjustable >>> >> >> >>>> regulators for stock. The board that I'm doing now has a 24-channel >>> >> >> >>>> analog mux to BIST the power supplies, using the dreadful Xilinx >>> >> >> >>>> 1-volt XADC that's inside their FPGAs. Free and worth it. >>> >> >> >>>> >>> >> >> >>>>> >>> >> >> >>>>>> You sure are in a bad mood lately. >>> >> >> >>>>>> >>> >> >> >>>>> I've noticed that lately with some regulars here, including a few >>> >> >> >>>>> who normally exhibit decent manners. >>> >> >> >>>> >>> >> >> >>>> Well, some never show any sign of manners. They are repulsive but >>> >> >> >>>> you've got to feel sorry for them, stuck being around themselves all >>> >> >> >>>> day. >>> >> >> >>>> >>> >> >> >>>> There's a basically perfect -1 correlation between being obnoxious and >>> >> >> >>>> designing electronics. >>> >> >> >>> >>> >> >> >>> Well, now that Jim Thompson is apparently no longer with us. :( >>> >> >> >>> >>> >> >> >>> He was a bit of a statistical outlier. >>> >> >> >> >>> >> >> >> He was crabby and dismissive of people not as smart as he was, and >>> >> >> >> hostile to people that might have been smarter, but he was >>> >> >> >> occasionally helpful, and had a sense of humor, and was very brave at >>> >> >> >> the end. >>> >> >> >> >>> >> >> > >>> >> >> >When he wasn't busy accusing peoples' wives of immoral behaviour, >>> >> >> >threatening folks with lawsuits or bodily harm, or siccing the FBI on >>> >> >> >some deserving individuals. ;) >>> >> >> >>> >> >> Gosh, nobody's perfect. >>> >> >> >>> >> >> > >>> >> >> >He was probably nice enough in person--we collaborated a couple of times >>> >> >> >but never met in person or even talked on the phone together. >>> >> >> > >>> >> >> >I agree that he had guts and seems to have died very well. >>> >> >> >>> >> >> I used a version of his clever CD ignition (without his permission) as >>> >> >> a gain-switched laser driver. Nice circuit. >>> >> >> >>> >> > I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more >>> >> > >>> >> > He did an ASIC gatedriver design for us, nice design, cheap like we like it >>> >> > >>> >> > Suddenly we did not hear from him again, so another ASIC designer took over at that point >>> >> > >>> >> > He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip >>> >> > >>> >> > Cheers >>> >> > >>> >> > Klaus >>> >> >>> >> Got to ask here, if I didn't years ago. How much different in behavior are >>> >> analog circuits layed out with discrete components from the final IC >>> >> itself? Let's talk pre computer simulations. For example, microwave and RF >>> >> boards are constructed different from audio circuit boards, but if you >>> >> look at a schematic, it's just a bunch of discretes wired together. >>> > >>> > It can be very simelar >>> > >>> > In our case, to keep NRE low, we needed to use almost only predefined blocks. When you team up with a fab, they supply all datasheets and simulation models for standard blocks. So, opamps, comparators, digital blocks, voltage references, PWM circuits and individual transistors >>> > >>> > The blocks are proven in the technology and simulation vs real life is 100% spot on. The tools are very expensive, but they model the chip to every detail. Thus, experienced ASIC designers never need to do new revisions. >>> > >>> > If you wander off, and do custom blocks, it gets a lot more expensive >>> > >>> > So you if you find a discrete opamp that matches your ASIC block, so can do proof of concept in discrete design >>> > If not, simulations is the way forward >>> > >>> > And by the way, prototypes with MOSIS is very cheap, you just need to wait a loooooong time from design to the first chips comes in >>> > >>> > >>> > Cheers >>> > >>> > Klaus >>> >>> Hmm. What about equivalent, full sized components? >>> >>> Take the example the 74LS00 nand gate, TI has a schematic >>> >>> https://html.alldatasheet.com/html-pdf/27361/TI/74LS00N/73/3/74LS00N.html >>> >>> Are there equivalent transistors and diodes used in that schematic I can >>> run out and buy, to make an as close to 100% electrically compatible, drop >>> in replacement? >>> >>> I'm not even sure what the first transitor is with A and B inputs is even >>> called. What is it? >> >> Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. >> >> You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. > >A very odd device. Are there other weird semiconductors like that?Unijunctions, point-contact diodes and transistors, some strange 4-layer things that played a part in Silicon Valley history, germanium jfets, tunnel diodes, electrolytic transistors, alloy-junction transistors, surface-barrier transistors, Schottky transistors, drift step-recovery diodes, dual-gate fets, reference zeners, silicon varistors, mesfets (almost gone), all kinds of weird stuff. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●May 26, 20202020-05-26
On Tuesday, May 26, 2020 at 10:16:29 AM UTC-4, Phil Hobbs wrote:> On 2020-05-26 09:01, Michael Terrell > > > > The 3N128 was popular in Amateur Radio projects in the '70s along with RCA's 40673 that was used in TV tuners and garage door openers. They used to cost me 36 cents, from the Linear corporation that built the openers. I bought them 25 at a time, and often ran out before more were available. These were very sensitive receivers, and with careful alignment many would operate a door from three blocks away. That was handy for fire stations. They could start the doors to open and have them open enough that they didn't have to wait to pull off the road when they returned after a fire run. the 406743 turn up in small batches from time to time, but they aren't worth $20 each. > > You can do the equivalent with a built-up cascode anyway. > > My very favorite dual-gate part was the Motorola MRF966 GaAs FET. You > just connected gate 2 to the source, and, presto, an almost perfectly > unilateral amplifier. I used to get > 70 dB isolation up to above 100 > MHz with one stage. > > I used to use them connected directly to coax as cheapo FET probes--the > pointy leads of the Macro-X package were perfect for that. > > I still have a couple of dozen, but haven't used one in ages.Back then, I only had a branch of Pioneer to buy parts from. It was called SREPCO, and it carried TV repair parts. Pioneer had an industrial branch in Dayton, Ohio but they only sold to corporations listed on Dunn and Bradstreet. SREPCO was a very early distributor in Electronics 'Standard Radio and Electronic Parts Company'. Those stores were closed, decades ago.
Reply by ●May 26, 20202020-05-26
On Tuesday, May 26, 2020 at 10:47:06 AM UTC-4,John Larkin wrote:> > Unijunctions, point-contact diodes and transistors, some strange > 4-layer things that played a part in Silicon Valley history, germanium > jfets, tunnel diodes, electrolytic transistors, alloy-junction > transistors, surface-barrier transistors, Schottky transistors, drift > step-recovery diodes, dual-gate fets, reference zeners, silicon > varistors, mesfets (almost gone), all kinds of weird stuff.Try to find a Stabistor these days. HP used them in the Harrison Labs designed power supplies as a reference. If it fails, all the outputs are wrong. I have several HP6236B supplies with bad Stabistors. I had to resort to buying a couple of the less popular 6237B model, for parts.
Reply by ●May 26, 20202020-05-26
On 2020-05-26 11:59, Michael Terrell wrote:> On Tuesday, May 26, 2020 at 10:16:29 AM UTC-4, Phil Hobbs wrote: >> On 2020-05-26 09:01, Michael Terrell >>> >>> The 3N128 was popular in Amateur Radio projects in the '70s along with RCA's 40673 that was used in TV tuners and garage door openers. They used to cost me 36 cents, from the Linear corporation that built the openers. I bought them 25 at a time, and often ran out before more were available. These were very sensitive receivers, and with careful alignment many would operate a door from three blocks away. That was handy for fire stations. They could start the doors to open and have them open enough that they didn't have to wait to pull off the road when they returned after a fire run. the 406743 turn up in small batches from time to time, but they aren't worth $20 each. >> >> You can do the equivalent with a built-up cascode anyway. >> >> My very favorite dual-gate part was the Motorola MRF966 GaAs FET. You >> just connected gate 2 to the source, and, presto, an almost perfectly >> unilateral amplifier. I used to get > 70 dB isolation up to above 100 >> MHz with one stage. >> >> I used to use them connected directly to coax as cheapo FET probes--the >> pointy leads of the Macro-X package were perfect for that. >> >> I still have a couple of dozen, but haven't used one in ages. > > > Back then, I only had a branch of Pioneer to buy parts from. It was called SREPCO, and it carried TV repair parts. Pioneer had an industrial branch in Dayton, Ohio but they only sold to corporations listed on Dunn and Bradstreet. SREPCO was a very early distributor in Electronics 'Standard Radio and Electronic Parts Company'. Those stores were closed, decades ago. >In Vancouver things were a bit looser--you just needed to make up a company name. A pal of mine called his "Enematronics" and nobody batted an eyelash. Canadian Electronics Limited (CEL) and Armaco were the leading places, but besides them and Rat Shack there was a ham shop within easy bicycling distance, called "Rendell-Paret Electronics", run by the estimable Hedley Rendell. (Not Hedy.) It was one of those grease-and-nicotine-encrusted places with old gear piled right up to the ceiling, barrels of surplus parts, the works. Hedley was always chain-smoking behind the counter. If there had been an earthquake, nobody would have gotten out alive. Some while later, when I was building satcom stuff for a couple of years, I remember phoning up J. W. Miller, looking for some coil or other. "Hi, Phil Hobbs calling. Could you tell me who your rep is in Vancouver?" "Sure, It's Rendell..." "<gales of laughter> No! You're kidding!" Good times. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
