So, to drag the discussion a little OT, is there an easy tutorial or design article about this FET current regulator somewhere? How do you set the current level?
I need to prototype a 20/40/80 etc.... ma regulator to drive some LED's for another project. :) Mike D. > Didn't you guys read my post?... ;-) > > It's really a JFET with the gate and the source shorted together. If > you look at the picture in > > http://photoman.bizland.com/diode.jpg > > you'll see that it is a FET - not a diode. It's some kind of voodoo > electronic speak (thanks Ronald) to call it a diode...but they did. It > is listed under the diode designations (1Nxxxx). > > (Perhaps the gate to drain can be considered a diode junction?...) > > Non-electronics people please disregard the above discussion... ;-)) > > Dan > > > Constant current two-terminal devices can be made by shorting the gate > and the source of a JFET together. When the FET is forward biased, this > results in a nearly constant current for voltages ranging from roughly > 2V up to 300V (or the breakdown voltage of the device in question). In > reverse bias, this kind of constant current device conducts as a > junction diode (so one can oppose two such devices in series to regulate > AC current). > > > > -----Original Message----- > From: Malcolm Stebbins [mailto:[email protected]] > Sent: Saturday, September 30, 2006 10:18 AM > To: [email protected] > Subject: Re: CS>Diodes with 3 leads ( Question and Use ) > > I could be wrong, but suspect the "three legged diodes" are actually a > reference to three-terminal current regulators - or possibly to voltage > regulators. These were mentioned a while ago as a method of getting > simple current regulation for CS generator applications, and in context > with regular regulator (current) diodes with two legs, not shortened > (Eeww! Sorry, almost) Malcolm > > At 11:28 AM 10/15/06 -0500, you wrote: > > >Morning V and The List, > > > > >> At 05:53 PM 10/14/2006, you wrote: > > > >> tere is a spec sheet that comes with theu little diodes that tells > > >> which leads to short together. > > > > I think you and others have used this term, "Which Leads to short > > together". > > > >It has been a bit confusing to me, raises some questions, and may be > >misleading to others. > > > >I have used many diodes over the years, likely numbering into the > >thousands. At one time, the systems in the field were not perfect, the > > >manufactures did not have all their ducks in a row, and we had to > >interface systems, build small circuits on the job site, and even piece > > >together a diode matrix now and then. I would buy them 50 and 100 at > >the time and felt I cold not hit the road without a bag of diodes. > > > >I thought I had used them in every imaginable fashion, but maybe not. > > > >Still, the term "which leads to short together" leave me in AWE and a > >state of confusion. > > > >Literally, shorting the leads together can mean only one thing. > That > >is, unless the mounting / support lead enters the picture. Short one > >lead to it ? > > > >Still, in my mind, Shorting the leads together can mean only one > thing. > > > >Possibly you are meaning, "Where to put the diode in the circuit" as > >it would appear to "short together" the two points, but in reality it > >does not. As you know, there is a forward voltage and near a constant > >current for reverse voltage use. > > > >Makes me wonder if several biased in reverse would not work as a > >current limiter. > > > >A short is a short is a short. How can anyone define it differently. > >Shorting the two leads together ( A two lead diode ) would render it > >useless and worthless. > > > >Not trying to muddy up the water that you and others have already > >cleared up, but don't want to see the beginner or the novice to proceed > with any > >confusion. Or ....... confusing terms. > > > >Here is a wonderful link for the person starting to learn about diodes. > >http://www.kpsec.freeuk.com/components/diode.htm > > > >There are many "not so normal uses" for diodes. In a bind, they can > >serve as a "Model Rocket Ignitor". > > > >Wayne > > > >======================= > > > > > -- > The Silver List is a moderated forum for discussing Colloidal Silver. > > Instructions for unsubscribing are posted at: http://silverlist.org > > To post, address your message to: [email protected] > > Address Off-Topic messages to: [email protected] > > The Silver List and Off Topic List archives are currently down... > > List maintainer: Mike Devour <[email protected]> > > [Mike Devour, Citizen, Patriot, Libertarian] [[email protected] ] [Speaking only for myself... ]
