Steve Wilson <no@spam.com> wrote:> For those who are interested, here are some links:> Electrons And Holes In Semiconductors > by William Shockley 1950 > http://preview.tinyurl.com/y77jxe6q> Radiotron Designers Handbook 1954 Edition > http://preview.tinyurl.com/hmnpj2r> Radiation Lab Series > http://www.febo.com/pages/docs/RadLab/> Reference Data For Engineers > http://preview.tinyurl.com/ycjcp6cp> Terman, 1943 > https://preview.tinyurl.com/ya5ho5dt> - url's verified on Tue, Nov 21, 2017 > - all links show a preview so you can see where they will take youTwo more for completeness Jim Williams Lab Notes http://www.introni.it/riviste_jim_williams.html Bob Pease Lab Notes http://www.introni.it/riviste_bob_pease.html
Need Op Amp for design
Started by ●November 19, 2017
Reply by ●November 21, 20172017-11-21
Reply by ●November 21, 20172017-11-21
On 2017-11-21 12:20, Winfield Hill wrote:> Joerg wrote... >> >> On 2017-11-21 11:35, Winfield Hill wrote: >>> John Larkin wrote... >>>> >>>> The ancient LM324 has PNP input transistors, and the >>>> safe input voltages can go to +32 irrespective of V+. >>> >> >> The datasheet says "Don't do that" though. Looking at >> the innards on page 4 it seems you'd hit a diode path to V+: > > That's ST's LM324A, their non-A part doesn't have the diodes. > >>> I also thought of PNP-input single-supply op-amps as >>> a good solution, but the O.P. seems not to notice. >> >> Even if there wasn't a diode path, wouldn't the >> then reversed BE junction zener somewhere around 6V? > > These old silicon IC pnp trannies don't suffer from a > low Veb breakdown. The abs max spec of most company's > LM324 says you can go 28/ 32V above the neg rail: e.g., > NSC, ON Semi, NXP, UTC, TI, Fairchild, Bay Linear, etc. >For a hobby design that may be ok but not some much for industrial. It's like "You can only use parts from the days when Frank still worked there" :-) -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●November 21, 20172017-11-21
On 2017-11-21 12:28, John Larkin wrote:> On Tue, 21 Nov 2017 12:05:59 -0800, Joerg <news@analogconsultants.com> > wrote: > >> On 2017-11-21 11:35, Winfield Hill wrote: >>> John Larkin wrote... >>>> >>>> The ancient LM324 has PNP input transistors, and the >>>> safe input voltages can go to +32 irrespective of V+. >>> >> >> The datasheet says "Don't do that" though. Looking at the innards on >> page 4 it seems you'd hit a diode path to V+: >> >> http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdf >> >> Quote page 4, footnote (1) "Neither of the input voltages must exceed >> the magnitude of (VCC+) or (VCC-)". >> >> > > The original National data sheet specifically allows +32 irrespective > of V+. Can't trust those eye-talian chips. [1] > > But DO NOT allow an input to go below V-, operating. All sorts of > weird stuff will happen. > >>> I also thought of PNP-input single-supply op-amps as >>> a good solution, but the O.P. seems not to notice. >>> >> >> >> Even if there wasn't a diode path, wouldn't the then reversed BE >> junction zener somewhere around 6V? > > PNPs tend to have higher zener voltage. The 324 must have some > special, old-fashioned diffusion. > > [1] And why do we sell them good wheat for a few dollars a bushel, and > let them add water, take out the water, and sell it back to us for $8 > a pound? >Worse. We sell them hide and they send Gucci stuff back to 5th Avenue that costs 1000x of what we sent. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●November 21, 20172017-11-21
On 2017-11-21 12:39, Joerg wrote:> On 2017-11-21 12:20, Winfield Hill wrote: >> Joerg wrote... >>> >>> On 2017-11-21 11:35, Winfield Hill wrote: >>>> John Larkin wrote... >>>>> >>>>> The ancient LM324 has PNP input transistors, and the >>>>> safe input voltages can go to +32 irrespective of V+. >>>> >>> >>> The datasheet says "Don't do that" though. Looking at >>> the innards on page 4 it seems you'd hit a diode path to V+: >> >> That's ST's LM324A, their non-A part doesn't have the diodes. >> >>>> I also thought of PNP-input single-supply op-amps as >>>> a good solution, but the O.P. seems not to notice. >>> >>> Even if there wasn't a diode path, wouldn't the >>> then reversed BE junction zener somewhere around 6V? >> >> These old silicon IC pnp trannies don't suffer from a >> low Veb breakdown. The abs max spec of most company's >> LM324 says you can go 28/ 32V above the neg rail: e.g., >> NSC, ON Semi, NXP, UTC, TI, Fairchild, Bay Linear, etc. >> > > For a hobby design that may be ok but not some much for industrial. It's > like "You can only use parts from the days when Frank still worked > there" :-) >BTW, even with well-vetted parts that can happen. One was a FET where production was humming just fine. One day the phone rang. "None of the boards since Thursday work and it's this one FET that always burns up". Turns out the manufacturer had "ESD-improved" the design by incorporating back-to-back gate to source zeners at 8V. The previous abs max Vgs was 20V and we had 12V on there. The abs max in the next Rev datasheet was 8V ... tzzzt ... PHUT. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●November 21, 20172017-11-21
On Tuesday, November 21, 2017 at 3:30:33 PM UTC-5, Steve Wilson wrote:> Steve Wilson <no@spam.com> wrote: > > > For those who are interested, here are some links: > > > Electrons And Holes In Semiconductors > > by William Shockley 1950 > > http://preview.tinyurl.com/y77jxe6q > > > Radiotron Designers Handbook 1954 Edition > > http://preview.tinyurl.com/hmnpj2r > > > Radiation Lab Series > > http://www.febo.com/pages/docs/RadLab/ > > > Reference Data For Engineers > > http://preview.tinyurl.com/ycjcp6cp > > > Terman, 1943 > > https://preview.tinyurl.com/ya5ho5dt > > > - url's verified on Tue, Nov 21, 2017 > > - all links show a preview so you can see where they will take you > > Two more for completeness > > Jim Williams Lab Notes > http://www.introni.it/riviste_jim_williams.html > > Bob Pease Lab Notes > http://www.introni.it/riviste_bob_pease.htmlThanks for all those Steve! George h.
Reply by ●November 21, 20172017-11-21
On 2017-11-21 13:15, George Herold wrote:> On Tuesday, November 21, 2017 at 3:30:33 PM UTC-5, Steve Wilson wrote: >> Steve Wilson <no@spam.com> wrote: >> >>> For those who are interested, here are some links: >> >>> Electrons And Holes In Semiconductors >>> by William Shockley 1950 >>> http://preview.tinyurl.com/y77jxe6q >> >>> Radiotron Designers Handbook 1954 Edition >>> http://preview.tinyurl.com/hmnpj2r >> >>> Radiation Lab Series >>> http://www.febo.com/pages/docs/RadLab/ >> >>> Reference Data For Engineers >>> http://preview.tinyurl.com/ycjcp6cp >> >>> Terman, 1943 >>> https://preview.tinyurl.com/ya5ho5dt >> >>> - url's verified on Tue, Nov 21, 2017 >>> - all links show a preview so you can see where they will take you >> >> Two more for completeness >> >> Jim Williams Lab Notes >> http://www.introni.it/riviste_jim_williams.html >> >> Bob Pease Lab Notes >> http://www.introni.it/riviste_bob_pease.html > > Thanks for all those Steve! > > George h. >Also, let's not forget the ARRL Handbook. That got me my start into the world of serious electronics, for very little money. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●November 21, 20172017-11-21
Joerg <news@analogconsultants.com> wrote:> Also, let's not forget the ARRL Handbook. That got me my start into the > world of serious electronics, for very little money.Yes. I also got started with Radiotron and ARRL. Very important. Many issues are now available on the web. ARRL QEX is also on the web. They give a free sample article with each issue: http://www.arrl.org/this-month-in-qex Many other books and magazines are also on the web. You just have to search a bit to find them. Sometimes the link will disappear, then reappear at a different location. So you have to verify the url before posting it. And download it before it disappears again!
Reply by ●November 22, 20172017-11-22
Joerg wrote...> >On 2017-11-21 12:20, Winfield Hill wrote: >> Joerg wrote... >>> >>> On 2017-11-21 11:35, Winfield Hill wrote: >>>> John Larkin wrote... >>>>> >>>>> The ancient LM324 has PNP input transistors, and the >>>>> safe input voltages can go to +32 irrespective of V+. >>>> >>> >>> The datasheet says "Don't do that" though. Looking at >>> the innards on page 4 it seems you'd hit a diode path to V+: >> >> That's ST's LM324A, their non-A part doesn't have the diodes. >> >>>> I also thought of PNP-input single-supply op-amps as >>>> a good solution, but the O.P. seems not to notice. >>> >>> Even if there wasn't a diode path, wouldn't the >>> then reversed BE junction zener somewhere around 6V? >> >> These old silicon IC pnp trannies don't suffer from a >> low Veb breakdown. The abs max spec of most company's >> LM324 says you can go 28/ 32V above the neg rail: e.g., >> NSC, ON Semi, NXP, UTC, TI, Fairchild, Bay Linear, etc. > > For a hobby design that may be ok but not some much for industrial. > It's like "You can only use parts from the days when Frank still > worked there" :-)Not at all in this case. It's the ST "A" part that's completely out of line, not a single other supplier of this true jelly-bean commodity part has played that game. -- Thanks, - Win
Reply by ●November 22, 20172017-11-22
On 2017-11-22 06:49, Winfield Hill wrote:> Joerg wrote... >> >> On 2017-11-21 12:20, Winfield Hill wrote: >>> Joerg wrote... >>>> >>>> On 2017-11-21 11:35, Winfield Hill wrote: >>>>> John Larkin wrote... >>>>>> >>>>>> The ancient LM324 has PNP input transistors, and the >>>>>> safe input voltages can go to +32 irrespective of V+. >>>>> >>>> >>>> The datasheet says "Don't do that" though. Looking at >>>> the innards on page 4 it seems you'd hit a diode path to V+: >>> >>> That's ST's LM324A, their non-A part doesn't have the diodes. >>> >>>>> I also thought of PNP-input single-supply op-amps as >>>>> a good solution, but the O.P. seems not to notice. >>>> >>>> Even if there wasn't a diode path, wouldn't the >>>> then reversed BE junction zener somewhere around 6V? >>> >>> These old silicon IC pnp trannies don't suffer from a >>> low Veb breakdown. The abs max spec of most company's >>> LM324 says you can go 28/ 32V above the neg rail: e.g., >>> NSC, ON Semi, NXP, UTC, TI, Fairchild, Bay Linear, etc. >> >> For a hobby design that may be ok but not some much for industrial. >> It's like "You can only use parts from the days when Frank still >> worked there" :-) > > Not at all in this case. It's the ST "A" part that's completely > out of line, not a single other supplier of this true jelly-bean > commodity part has played that game. > >That can work if there is explicit warning in the company parts database that the ST A version is not ECO-released and never to be purchased as substitute. Without that it'll be risky especially if contract assemblers are used (got some stories there). What tops that is the BSS83 which comes in a P-channel and an N-channel flavor. One has a P behind it but that can be overlooked. Both born in Europe. Beats me how that could happen. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●November 23, 20172017-11-23
On 2017-11-20, Leslie Rhorer <rhorerles@gmail.com> wrote:>> I'm not sure and it may depend on the opamp, > > Yes, it does. > >> but the opamp input >> may draw current,even when the power is not applied. (It may draw more >> current.) Since it's all one polarity can you use some fet's to turn the >> inputs on and off? > > Indeed some Op Amps will. The LM324 will not because the inputs are > the bases of PNP transistors, unless the input voltage exceeds the > reverse breakdown voltage of the base-emitter junction.Techically it will, 0 is nore than -60uA (or whatever the bias current is). :) -- This email has not been checked by half-arsed antivirus software
