for at komme i gang..

nk p=E5

ere

riabel

Det er s=E5 en skam at det ikke kan svare sig:

-- Benny

Et "oratorie-aggregat"

-er det noget til sangere ??

Bo //

Hej Benny

Det er da så fordi man ikke fatter hvad en god forretning er.

--
Mvh Max

"Benny Andersen" skrev i en meddelelse

Hvis vi et øjeblik ser bort fra tilfredsstillelsen og det man rent faktisk lære ved at bygge selv , og som var det jeg talte om. Ja så har du delvist ret ..

Jeg ville godt kunne bygge en Laboratoriestrømforsyning med de specs som du linker til for under 1250 Kr , men det er kun fordi at jeg jo efter rigtig manger år med elektronik som hobby , har et større lager af komponenter kasser ringkernetrafoer o.s.v.

En nybegynder vil naturligvis ikke have den mulighed og prisen vil for ham blive pænt høj , men jeg er næsten overbevist om at kvaliteten af komponenterne ved selvbyg langt overgår kvaliteten af hvad du finder i en Ningbo FTZ Hopewell.

OG bye the way

Lidt småt kan også gøre det

eller den billige !

Den estetiske :o)

--
Venlig Hilsen
Michael Meidahl Jensen

Hej!

Svar til dette indlæg sendes til: nttp://dk.teknik.elektronik

-

En digital-immigrant vil sandsynligvis opfatte et analogt ur lettest

og

en digital-native vil sandsynligvis opfatte et digitalt ur lettest

;-)

-

Og nu til en kæmpe perspektivering ;-)

Hjernen - den ved vi grundlæggende set ikke hvordan fungerer?

Her er "lidt" information til at nuancere jeres opfattelse af dyrs og menneskers hjerner - og "lidt" om vores manglende viden om neuroner:

2004-06-16, Sciencedaily: Gray Matters: New Clues Into How Neurons Process Information: Citat: "... "It's amazing that after a hundred years of modern neuroscience research, we still don't know the basic information processing functions of a neuron," said Bartlett Mel. ... "For lack of a better idea, it has always been thought that a brain cell sums up its excitatory inputs linearly, meaning that the excitation caused by two inputs A and B activated together equals the sum of excitations caused by A and B presented separately."

"We show that the cell significantly violates that rule," Mel said.

The team found that the summation of information within an individual neuron depends on where the inputs occur, relative to each other, on the surface of the cell. ... While the results are promising, the team is certain this is not the final word on the pyramidal neuron. ... "Undoubtedly, this is still too simple a model," Mel said. "But the two-layer model is a better description, it seems, than to assume that the neuron is simply combining everything linearly from everywhere. That's clearly not what these data show." ... Mel emphasizes that the "arithmetic" rules he and his colleagues found in pyramidal neurons may not apply to all neurons in the brain.

"There are other neurons that have different shapes, inputs, morphologies and ion channels," he said. "There might be a dozen different answers to the question, depending on what neuron you're looking at." ... [ Bemærk: Dette er en tentativ model - vi ved ikke om hjernen fungerer eksakt som en computer!: ] "We tend to view the brain as a computer," he said. "If we want to figure out how this computer works, we must first know how its separate parts function." ..."

-

Vores hjerne er temmelig plastisk - også efter teenageårene:

February 6, 2006, Sciencedaily: Brain Changes Significantly After Age

18, Says Dartmouth Research: Citat: "..."The brain of an 18-year-old college freshman is still far from resembling the brain of someone in their mid-twenties," says Bennett. "When do we reach adulthood? It might be much later than we traditionally think."..."

Nov. 14, 2007 Certain Mature Neurons Can Retain A Youthful Form Of Plasticity:

Citat: "... It's a general belief that the circuitry of young brains has robust flexibility but eventually gets "hard-wired" in adulthood. As Johns Hopkins researchers and their colleagues report in the Nov. 8 issue of Neuron, however, adult neurons aren't quite as rigidly glued in place as we suspect. ... Why the brain would want such motile, non-connected branches is the next mystery to tackle. Linden thinks they may present a second mechanism for conveying information beyond traditional synapses or assist in nerve regeneration, quickly forming synapses should nearby nerves get damaged. ..."

May 29, 2008, Brain Cells Help Neighboring Nerves Regenerate:

Dec. 22, 2007 Neuronal Circuits Able To Rewire On The Fly To Sharpen Senses:

Citat: "... Researchers from the Center for the Neural Basis of Cognition (CNBC), a joint project of Carnegie Mellon University and the University of Pittsburgh, have for the first time described a mechanism called "dynamic connectivity," in which neuronal circuits are rewired "on the fly" allowing stimuli to be more keenly sensed. ... "If you think of the brain like a computer, then the connections between neurons are like the software that the brain is running. Our work shows that this biological software is changed rapidly as a function of the kind of input that the system receives," said Nathan Urban, associate professor of biological sciences at Carnegie Mellon. ..."

Apr. 13, 2006 Brain Communicates In Analog And Digital Modes Simultaneously:

Citat: "... Contrary to popular belief, brain cells use a mix of analog and digital coding at the same time to communicate efficiently, according to a study by Yale School of Medicine researchers published this week in Nature. ... "This study reveals that the brain is very sophisticated in its operation, using a code that is more efficient than previously appreciated," said David McCormick, professor in the Department of Neurobiology and senior author of the study. "This has widespread implications, not only for our basic understanding of how the brain operates, but also in our understanding of neuronal dysfunction."

"It's as if everyone thought communication in the brain was like a telegraph, but actually it turned out to be more similar to a telephone," he said. ... This means that the waveform generated in the receiving neuron is not just determined by the digital pattern of action potentials generated, but also by the analog waveform occurring in the sending neuron. ... McCormick said future investigations and models of neuronal operation in the brain will need to take into account the mixed analog-digital nature of communication. Only with a thorough understanding of this mixed mode of signal transmission will a truly in depth understanding of the brain and its disorders be achieved, he said. ..."

Apr. 2, 2007 It's Only A Game Of Chance: Leading Theory Of Perception Called Into Question:

Citat: "... The validity of a leading theory that has held a glimmer of hope for unraveling the intricacies of the brain has just been called into question. Dr. Ilan Lampl of the Weizmann Institute of Science's Neurobiology Department has produced convincing evidence to the contrary. His findings recently appeared in the journal Neuron. ... The consequence of this research is likely to contribute significantly to the ongoing debate on neuronal coding. Lampl: "Since the 1980s, many neuroscientists believed they possessed the key for finally beginning to understand the workings of the brain. But we have provided strong evidence to suggest that the brain may not encode information using precise patterns of activity." ..."

Mar. 5, 2007 Neurons That Detect Motion Rapidly Switch Between Modes Of Data Collection:

Citat: "... The findings are just the latest to suggest that sensory neurons are more "plastic" than believed, says co-author Thomas Albright, director of the Vision Center Laboratory. "One of the tenets of sensory neurobiology over the last 40 years has been that neurons are hard wired, that there is not a lot of room for change," he says. "That view is being increasingly eroded due to evidence that these cells can change the way they represent information based on sensory input." ... Vision is thus an act of dynamic interpretation requiring highly flexible processing. ..."

-

Forbedred jer på endnu mere kompleksitet:

Kig i kildernes overskrifter og citater her:

Mon genekspressionskoncerten påvirker neuronernes "adfærd/beregning"? Og dermed os?:

Dec. 12, 2007 When She's Turned On, Some Of Her Genes Turn Off, Fish Study Shows:

Citat: "... When a female is attracted to a male, entire suites of genes in her brain turn on and off, show biologists from The University of Texas at Austin studying swordtail fish. ... This is one of few studies to link changes in the expression of genes with changes in an individual's behavior in different social situations ... "What we have not appreciated until now is how dynamic the genome is," said Hofmann. "It is constantly changing and even in a very short period of time, 10 percent of the protein-coding genome can change its activity. We now have a genomic view of these dynamic processes within a social context." ..."

Swordtail fish er vist sådan en her:

Apr. 23, 2008 Nurture Over Nature: Certain Genes Are Turned On Or Off By Geography And Lifestyle, Study Suggests:

Citat: "... Although Idaghdour initially hypothesized that environmental factors would play a role in gene expression, he didn't expect such large differences. About 30 percent of genes were differentially expressed between urban dwellers and mountain agrarians. ..."

1. sep 2007 Ny DNA-kortlægning: Vi er langt mere forskellige, end vi troede:
   formatting link
   Citat: "... Du kan have adskillige gener, der disponerer, at du får kongeblå øjne, sofa-håndtag, krøller og en yderst høj risiko for at få en blodprop. Alligevel kan du ligeså vel ende med at blive en slank starut med skaldet isse, grønne øjne og aldrig opleve, at et af dine blodkar bliver tilstoppet.

Vores genetiske koder er nemlig langt mere komplicerede og unikke, end videnskaben hidtil har troet. ..."

August 15, 2007 Conquest Of Land Began In Shark Genome:

Citat: "... Scientists at the University of Florida have identified genetic activity in sharks required for the development of hands, feet, fingers and toes in limbed animals. ... Genetic processes were not simple in early aquatic vertebrates only to become more complex as the animals adapted to terrestrial living. They were complex from the outset. ..."

hilsen

Glenn

"Klaus D. Mikkelsen" wrote in message news: snipped-for-privacy@du.kan.finde.den...

Civilingeniører.

/Bo.

Typisk - h=E5ber ikke jeg g=E5r dig i bedende n=E5r jeg nu har sendt en mai= l til elfa om deres gennemg=E5ende stavefejl. Ikke at jeg det interesser mig synderligt, men jeg vil da lige chekke ved senere lejlighed.

T=E6nker du p=E5 at det er noget kinabras eller er det forretningsaspekter af mindre m=E5lbar slags. Tror heller ikke jeg ville k=F8be noget s=E5 udokumenteret. Jeg er p=E5 elfa's mailliste - ofte sletter jeg blot, men s=E5 kiggede jeg for en gang skyld og huskede denne tr=E5d.

-- Benny

BWYX/F8ETXLNFGR...

Ja - det kan derimod svare sig! OP har jo ogs=E5 efterspurgt 1,5-12v, 4a - min gamle 300W var p=E5 15A ved

12v Anvendelse af pc-psu: Hvis man kun g=E5r efter sp=E6ndingsregulering med 'fold back' p=E5 den max str=F8m som regulatoren er lavet til, er det s=E5 ikke forholdvis enkelt? Findes der en 'enkelt-kreds' l=F8sning der kan fungere afs=E6ttende 40W p= =E5 en passende k=F8leplade?

Nu vi er ved det kreative, hvad s=E5 med selv at bygge loddekolbe temperaturstyringen. OP har jo eksperimentboard. Man kunne jo k=F8be s=E5dan en:

uct&R=3D2007722#header

Ligner den med ferrokonstant sensor i varmeelemenet - diagram baseret p=E5 TL082+LM317+BD244+diverse kan eksponeres om =F8nsket.

-- Benny

Hej Benny

Nej, jeg tænker på den lærdom man høster ved at bygge selv, den har en meget større værdi end de småbeløb selve byggeriet koster og er dermed en fandens god forretning,.

--
Mvh Max

Noget faglitteratur - det kan givet købes antikvarisk ellers kan det sikkert lånes på biblioteket. Med moderne digitalcameraer er det ingen sag at affotografere det der er interessant.

Nogle forslag.

Vejen til Sendetilladelsen 6. udgave er formentligt noget af det ypperste.

Så har Niels Dreijer skrevet læssevis af små håndbøger igennem 1980'erne om forskellige grene af selvbyg oh eksperimenter.

Jan Soelbergs Anvendt Elektronik

Jeg kan også huske en lille tyk bog af J. Fialla og B. Almind fra midt i

70'erne - kan ikke huske hvad den hedder men den er utroligt godt skrevet. Den hjalp mig igang for alvor da jeg var stor knægt.

Elektronik Ståbi fra Teknisk Forlag (Når du er kommet godt igang og gerne vil designe selv)

/Lars

1 - 0 til Max

/Lars

Apropo:

Jeg har den boken, første utgave. Den var bra den gang. For en 1 1/2 tiår siden bar jeg nede på bokhandelen og etterspurte en nyere utgave, og fikk beskjeden, at slikt ikke fantes. Nå er jeg imidlertid klar over at den finnes i en enda nyere utgave. Spørsmålet er så, Er denne nyeste utgaven verdt pengene i denne internett-tiden?

HM

Jeg kender ingen svenske butikker, men et par danske og tyske, søg på "sortiment":

Tomas

Du skal ikke gå i mine bede :-)

Jeg har osse sendt en mail. Efterhånden er der MANGE steder, hvor man ikke fatter en nogetsomhelst.

Jeg fangede RadioParts i at oplyse tolerancen på et krystal til at være

+/-100 sider pr minut. (sådan går det, når een eller anden handelsskoleelev skal oversætte ppm...)

Bo //

Universal instrument, kaffe og tålmodighed, der er jeg dækket ind.. høreværn og briller har jeg også .. men har det nok ikke på mens jeg fumler med dette..

;)

Lars

"Michael Meidahl Jensen" skrev i en meddelelse news:49aee903$0$56796$ snipped-for-privacy@dtext02.news.tele.dk...

Jeg kan godt følge dig med loddekolben, men er stadig en smule i tvivl ang. hvad prisleje man skal jagte..

Synes måske den der ESD er lidt dyr, til at starte med .. men samtidig kan jeg godt se fordelen i at vænne sig til en kolbe, og så ikke ha brug for at skifte den ud senere..

God info på loddetråden ..

mht strømmen har jeg kigget lidt på den her :

og

tænker måske at tage en af hver ..