On Thu, 23 Jul 2009 14:30:02 -0700 (PDT), fungus <openglMYSOCKS@artlum.com> wrote:>On Jul 23, 2:03�pm, default <defa...@defaulter.net> wrote: >> >> The coil can be wound with a tap or separately. �If you use a tap and >> keep winding in the same direction it will be phased right. >> > >I assume the winding after the tap has to go over the top of the >previous winding, right?No. They can be side by side. There may be some slight advantage to covering the whole toroid (ferrite bead) core (if that's what you have) with the collector winding to keep magnetic leakage low. I'd put the collector winding closer to the core or just wind them side by side. I like to wind bifilar when winding two windings with the same turns count on a core. It is slightly more hassle to phase correctly, but if my turns count is off, it will be off proportionately on both windings (which is important when the winding has to be balanced - which is not the case here) --
Joule Thief - still not working....
Started by ●July 23, 2009
Reply by ●July 23, 20092009-07-23
Reply by ●July 23, 20092009-07-23
On Jul 23, 10:18=A0pm, "bw" <bweg...@hotmail.com> wrote:> > Start with the original circuit, and get it to work on one battery. > > then go from there to what you want to do.That's what I'm doing... The original circuit lights up a LED but the current is very low - about 5mA. To drive six LEDs at 20mA with one battery you'd have to get the frequency up into the mHz (which isn't going to happen). The solution seems to be to raise the input voltage so that's what I'm trying to get working. Unfortunately I never studied electronics beyond what they told me in high-school physics class so I'm at a disadvantage.
Reply by ●July 23, 20092009-07-23
On Jul 23, 4:27=A0pm, Jon Kirwan <j...@infinitefactors.org> wrote:> > BJT temperature is related (obviously) to its power dissipation. =A0That > power dissipation comes from a variety of possible corners from my > hobby viewpoint: =A0(1) =A0The transistor has been damaged (diode put in > later, after it was already ruined perhaps?) and isn't operating well > anymore;Fresh transistors are quite frequent at the moment...> or, (2) the base-emitter junction current;I've moved the resistor in between the inductor and transistor to try to limit this (ie. R1 is now exactly as shown in the scematic). Doesn't seem to help much.> (3) collector-emitter current times collector-emitter voltage;I'm suspecting this at the moment.> (4) frequency of operation is too high for the reverse transit > time of the BJT. >Not sure I understand that.> So wind more turns and get the frequency near or under 100kHz, or so, > where the reverse transit will be only be a few percent or so and > won't be wasting a lot of power. >ie. Lower frequencies mean the transistor will be switched on for less percentage of the time and more electrons will go through the load instead of being dumped to ground via the transistor. (Yeah, I know - http://xkcd.com/567/ ).
Reply by ●July 23, 20092009-07-23
On Jul 23, 11:54=A0pm, default <defa...@defaulter.net> wrote:> On Thu, 23 Jul 2009 14:30:02 -0700 (PDT), fungus > > <openglMYSO...@artlum.com> wrote: > >On Jul 23, 2:03=A0pm, default <defa...@defaulter.net> wrote: > > >> The coil can be wound with a tap or separately. =A0If you use a tap an=d> >> keep winding in the same direction it will be phased right. > > >I assume the winding after the tap has to go over the top of the > >previous winding, right? > > No. =A0They can be side by side. >I'm not sure I'm being clear (my bad), I mean do they have to be like this: ABABABABABABAB =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D | BABABABABABABA tap or can they be: AAAAAAA BBBBBBBB =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D AAAAAAA | BBBBBBBB tap (view with monospace font...) On the rusty nail he uses a twisted pair
Reply by ●July 23, 20092009-07-23
On Thu, 23 Jul 2009 20:32:20 GMT, Jon Kirwan <jonk@infinitefactors.org> wrote:>On Thu, 23 Jul 2009 13:23:15 -0700, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Thu, 23 Jul 2009 19:04:43 GMT, Jon Kirwan >><jonk@infinitefactors.org> wrote: >> >>>On Thu, 23 Jul 2009 09:24:55 -0700, John Larkin >>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Thu, 23 Jul 2009 04:20:21 -0700 (PDT), fungus >>>><openglMYSOCKS@artlum.com> wrote: >>>> >>>>>I just got some proper parts to start making joule thieves but I'm >>>>>still >>>>>having problems. >>>>> >>>>>The circuit is this: http://www.artlum.com/jt/joulethief.gif >>>>> >>>>>Except I have R1 and L1 one the other way around (as in the original >>>>>web page at http://www.emanator.demon.co.uk/bigclive/joule.htm ) >>>>> >>>>>The problem is that my transistors keep on overheating and dying. >>>>>Why should this be? I'm using a 2N2222 in metal can (as shown here >>>>>http://en.wikipedia.org/wiki/2N2222 ). These can switch at hundreds >>>>>of megahertz so I don't think it's because of slow switching. >>>>> >>>>>I measured the current at point X and it seems high - over 100mA. >>>>>Could this be the cause of the overheating? Even if it isn't the >>>>>problem >>>>>it seems wasteful. I tried putting in a resistor there but the circuit >>>>>shuts down. >>>>>. >>>>>I also tried a honking big "high speed switching" transistor pulled >>>>>out of a PSU but it made the LEDs go very dim. >>>>> >>>>>Any ideas? >>>> >>>>That's a horrible circuit. Too many conflicting parameters depend on >>>>the value of R1. A proper blocking oscillator uses an RC time constant >>>>to set the rep rate, and a separate resistor to limit the base >>>>current. >>>> >>>>ftp://jjlarkin.lmi.net/BlockOsc.JPG >>> >>>Would you care to provide some sample values and analyze that circuit >>>for us? >> >>No, too much work. > >Hmm. > >Just to goose things along, for the joule thief circuit I get >something like this for the frequency: > > (Vbattery - Vsat) * (Vout + Vfreewheeldiode - Vbattery) >f = ------------------------------------------------------- > Ic_peak * L_collector * (Vout + Vfreewheeldiode - Vsat) > >Ic_peak may require an iteration or two with a datasheet to >approximate. I just go in with an assumed Ic, look up a beta estimate >for that on one curve and then grab the Vbe estimate from another >curve, and apply them into: > >Ic_peak = beta*(Nratio*(Vbattery - Vsat) + Vbattery - Vbe))/Rbase > >That Ic_peak is then used to repeat the process. When it settles, >I've usually got a reasonable figure that I can use to compute 'f'. >(Nratio is the turns ratio, usually just 1.) I tend to use Vsat=0.2V. > >If your suggestion is so nicely designable, can't you at least provide >an approximate equation? > >>>I see the RC node moving towards a bias point, but not really >>>setting the frequency at which the BJT goes on and off. But I haven't >>>sat down more than to glance over it, yet. >> >>In general, "on" pulse width is set by the volt-second saturation of >>the inductor (although a small value of C can make it shorter.) > >So in your circuit case, it does depend on saturation of the core. >What would happen in an air core case?The classic tube "blocking oscillator" had its ON time determined by inductor saturation. If it can't saturate, the ON interval ends when the transistor runs out of beta (or the tube out of plate current), or when C runs out of charge to drive the base/grid. The "blocking" part was the negative swing on the tube grid from grid current charging the cap; it fired again when R1 charged the grid the other way, back to the turnon threshold.> >>Base >>current is limited by R2 (the one connected to the base.) While the >>transistor's on, the base current charges up the cap, and that charge >>will back-bias the transistor until R1 recharges the cap back up to >>+0.7 volts, at which it fires again. >> >>Something like that. >> >>Try R1=1K, R2=100 C=100nF as very rough starting points. A lot depends >>on the inductor. It won't Spice unless the model includes inductor >>saturation. > >Yes. I gather.Unless L can't saturate, of course. Then it's not an official "blocking oscillator."> >>It's probebly easier to use a Tiny Logic schmitt-trigger oscillator to >>drive the transistor, and just use a single-winding inductor. Blocking >>oscillators are tricky. > >Single BJTs are cheap and, if you saw one of the web sites mentioned >some time back in the related thread, you'd have seen that the whole >thing is tiny enough to place inside a small flashlight bulb base.If you don't mind the 2-winding coil, and the additional futzing, the blocking oscillator is potentially cheap.> >... > >Since you write, "That's a horrible circuit. Too many conflicting >parameters depend on the value of R1. A proper blocking oscillator >uses an RC time constant to set the rep rate, and a separate resistor >to limit the base current," shouldn't it be the case that you can tell >me how to compute the frequency with ease? Isn't that the entire >point of saying all that? Or did I miss your point, here?As I said, a blocking oscillator is complex. I can't define the frequency "with ease." But having separate control over base drive and rep-rate helps orthogonalize things. Having one part control two circuit parameters can get awkward. Three is a nightmare. The MIT RadLab books are full of blocking oscillator theory and circuits, especially vol 19. Tube radars were full of them, as oscillators, comparators, pulse regenerators, and frequency dividers. Some texts referred to rf squegging circuits as blocking oscillators. John
Reply by ●July 23, 20092009-07-23
fungus wrote:> On Jul 23, 1:52 pm, David Eather <eat...@tpg.com.au> wrote: >> fungus wrote: >>> Any ideas? >> Yes. Figure out what you want to do and state it explicitly and exactly. >> Then work to that goal in steps you understand. > > a) I want to light up some LEDs (eg. six of them) using batteries, eg. > three AAAs. Circuit is decorative and has to be small because I want > to hide it. > > b) I want them to be as bright as possible - the full 20mA or as close > to it as I can get. > > c) It's a battery ... so voltage is going to drop over time (from 4.6V > to > 3.3V), this makes part (b) problematic. I accept that current will > drop > a bit, but if it can stay in the range 15-20mA then that's Ok. > > I've figured out that a Joule Thief is much closer to these > characteristics > than a simple resistor circuit doesn't. See the graph I plotted here: > http://www.artlum.com/jt/jt_vs_res.gif > > But ... at the moment it's eating up transistors.What voltage are you running the joule thief on?
Reply by ●July 23, 20092009-07-23
On Thu, 23 Jul 2009 15:53:44 -0700 (PDT), fungus <openglMYSOCKS@artlum.com> wrote:>On Jul 23, 11:54�pm, default <defa...@defaulter.net> wrote: >> On Thu, 23 Jul 2009 14:30:02 -0700 (PDT), fungus >> >> <openglMYSO...@artlum.com> wrote: >> >On Jul 23, 2:03�pm, default <defa...@defaulter.net> wrote: >> >> >> The coil can be wound with a tap or separately. �If you use a tap and >> >> keep winding in the same direction it will be phased right. >> >> >I assume the winding after the tap has to go over the top of the >> >previous winding, right? >> >> No. �They can be side by side. >> > >I'm not sure I'm being clear (my bad), I mean do >they have to be like this: > > ABABABABABABAB >================= > | BABABABABABABA >tap > >or can they be: > >AAAAAAA BBBBBBBB >================== >AAAAAAA | BBBBBBBB > tap > >(view with monospace font...) > >On the rusty nail he uses a twisted pairEither way. The top example might produce slightly better results but I couldn't say for sure. As the winding spreads out, inductance per turn goes down and resistance goes up (all other things being equal again) so the Q might be slightly lower, for any benefit gained by keeping the leakage lower. No advantage, I can think of, to using a twisted pair. You mentioned a ferrite rod or bar? Leave a little bit of ferrite rod with no coil over the ends (about 1/2 -2 X the diameter of the rod) don't wind right to the ends. When I was a kid we'd use center tapped filament transformers for blocking oscillators, and then use them to step up voltage to get 500-1000 volts from a battery supply. I tried that with a tapped modem transformer recently and even though the primary to secondary ratio was only 1:2 the output voltage was ~350 volts with 12V input (because the wave form contains a large spike). --
Reply by ●July 23, 20092009-07-23
On Jul 23, 7:20=A0am, fungus <openglMYSO...@artlum.com> wrote:> I just got some proper parts to start making joule thieves but I'm > still > having problems. > > The circuit is this:http://www.artlum.com/jt/joulethief.gifThat kind of oscillator (blocking oscillator) depends on saturation of the core, which is quite difficult to engineer (and somewhat energy-lossy). Unless you really need a minimum-parts solution, it's easier to run a '555 oscillator into an autotransformer to boost voltage. Remember to use DC blocking capacitors, and you can get nearly half a watt from such a circuit.
Reply by ●July 23, 20092009-07-23
On Thu, 23 Jul 2009 16:06:41 -0700, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>On Thu, 23 Jul 2009 20:32:20 GMT, Jon Kirwan ><jonk@infinitefactors.org> wrote: > >>On Thu, 23 Jul 2009 13:23:15 -0700, John Larkin >><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Thu, 23 Jul 2009 19:04:43 GMT, Jon Kirwan >>><jonk@infinitefactors.org> wrote: >>> >>>>On Thu, 23 Jul 2009 09:24:55 -0700, John Larkin >>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>>On Thu, 23 Jul 2009 04:20:21 -0700 (PDT), fungus >>>>><openglMYSOCKS@artlum.com> wrote: >>>>> >>>>>>I just got some proper parts to start making joule thieves but I'm >>>>>>still >>>>>>having problems. >>>>>> >>>>>>The circuit is this: http://www.artlum.com/jt/joulethief.gif >>>>>> >>>>>>Except I have R1 and L1 one the other way around (as in the original >>>>>>web page at http://www.emanator.demon.co.uk/bigclive/joule.htm ) >>>>>> >>>>>>The problem is that my transistors keep on overheating and dying. >>>>>>Why should this be? I'm using a 2N2222 in metal can (as shown here >>>>>>http://en.wikipedia.org/wiki/2N2222 ). These can switch at hundreds >>>>>>of megahertz so I don't think it's because of slow switching. >>>>>> >>>>>>I measured the current at point X and it seems high - over 100mA. >>>>>>Could this be the cause of the overheating? Even if it isn't the >>>>>>problem >>>>>>it seems wasteful. I tried putting in a resistor there but the circuit >>>>>>shuts down. >>>>>>. >>>>>>I also tried a honking big "high speed switching" transistor pulled >>>>>>out of a PSU but it made the LEDs go very dim. >>>>>> >>>>>>Any ideas? >>>>> >>>>>That's a horrible circuit. Too many conflicting parameters depend on >>>>>the value of R1. A proper blocking oscillator uses an RC time constant >>>>>to set the rep rate, and a separate resistor to limit the base >>>>>current. >>>>> >>>>>ftp://jjlarkin.lmi.net/BlockOsc.JPG >>>> >>>>Would you care to provide some sample values and analyze that circuit >>>>for us? >>> >>>No, too much work. >> >>Hmm. >> >>Just to goose things along, for the joule thief circuit I get >>something like this for the frequency: >> >> (Vbattery - Vsat) * (Vout + Vfreewheeldiode - Vbattery) >>f = ------------------------------------------------------- >> Ic_peak * L_collector * (Vout + Vfreewheeldiode - Vsat) >> >>Ic_peak may require an iteration or two with a datasheet to >>approximate. I just go in with an assumed Ic, look up a beta estimate >>for that on one curve and then grab the Vbe estimate from another >>curve, and apply them into: >> >>Ic_peak = beta*(Nratio*(Vbattery - Vsat) + Vbattery - Vbe))/Rbase >> >>That Ic_peak is then used to repeat the process. When it settles, >>I've usually got a reasonable figure that I can use to compute 'f'. >>(Nratio is the turns ratio, usually just 1.) I tend to use Vsat=0.2V. >> >>If your suggestion is so nicely designable, can't you at least provide >>an approximate equation? >> >>>>I see the RC node moving towards a bias point, but not really >>>>setting the frequency at which the BJT goes on and off. But I haven't >>>>sat down more than to glance over it, yet. >>> >>>In general, "on" pulse width is set by the volt-second saturation of >>>the inductor (although a small value of C can make it shorter.) >> >>So in your circuit case, it does depend on saturation of the core. >>What would happen in an air core case? > >The classic tube "blocking oscillator" had its ON time determined by >inductor saturation. If it can't saturate, the ON interval ends when >the transistor runs out of beta (or the tube out of plate current), or >when C runs out of charge to drive the base/grid. The "blocking" part >was the negative swing on the tube grid from grid current charging the >cap; it fired again when R1 charged the grid the other way, back to >the turnon threshold. > >> >>>Base >>>current is limited by R2 (the one connected to the base.) While the >>>transistor's on, the base current charges up the cap, and that charge >>>will back-bias the transistor until R1 recharges the cap back up to >>>+0.7 volts, at which it fires again. >>> >>>Something like that. >>> >>>Try R1=1K, R2=100 C=100nF as very rough starting points. A lot depends >>>on the inductor. It won't Spice unless the model includes inductor >>>saturation. >> >>Yes. I gather. > >Unless L can't saturate, of course. Then it's not an official >"blocking oscillator." > >> >>>It's probebly easier to use a Tiny Logic schmitt-trigger oscillator to >>>drive the transistor, and just use a single-winding inductor. Blocking >>>oscillators are tricky. >> >>Single BJTs are cheap and, if you saw one of the web sites mentioned >>some time back in the related thread, you'd have seen that the whole >>thing is tiny enough to place inside a small flashlight bulb base. > >If you don't mind the 2-winding coil, and the additional futzing, the >blocking oscillator is potentially cheap. > >> >>... >> >>Since you write, "That's a horrible circuit. Too many conflicting >>parameters depend on the value of R1. A proper blocking oscillator >>uses an RC time constant to set the rep rate, and a separate resistor >>to limit the base current," shouldn't it be the case that you can tell >>me how to compute the frequency with ease? Isn't that the entire >>point of saying all that? Or did I miss your point, here? > >As I said, a blocking oscillator is complex. I can't define the >frequency "with ease." But having separate control over base drive and >rep-rate helps orthogonalize things. Having one part control two >circuit parameters can get awkward. Three is a nightmare. > >The MIT RadLab books are full of blocking oscillator theory and >circuits, especially vol 19. Tube radars were full of them, as >oscillators, comparators, pulse regenerators, and frequency dividers. > >Some texts referred to rf squegging circuits as blocking oscillators.--- Translation: I don't have a clue. JF
Reply by ●July 23, 20092009-07-23
On Thu, 23 Jul 2009 16:06:41 -0700, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>On Thu, 23 Jul 2009 20:32:20 GMT, Jon Kirwan ><jonk@infinitefactors.org> wrote: > >>On Thu, 23 Jul 2009 13:23:15 -0700, John Larkin >><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Thu, 23 Jul 2009 19:04:43 GMT, Jon Kirwan >>><jonk@infinitefactors.org> wrote: >>> >>>>On Thu, 23 Jul 2009 09:24:55 -0700, John Larkin >>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>>On Thu, 23 Jul 2009 04:20:21 -0700 (PDT), fungus >>>>><openglMYSOCKS@artlum.com> wrote: >>>>> >>>>>>I just got some proper parts to start making joule thieves but I'm >>>>>>still >>>>>>having problems. >>>>>> >>>>>>The circuit is this: http://www.artlum.com/jt/joulethief.gif >>>>>> >>>>>>Except I have R1 and L1 one the other way around (as in the original >>>>>>web page at http://www.emanator.demon.co.uk/bigclive/joule.htm ) >>>>>> >>>>>>The problem is that my transistors keep on overheating and dying. >>>>>>Why should this be? I'm using a 2N2222 in metal can (as shown here >>>>>>http://en.wikipedia.org/wiki/2N2222 ). These can switch at hundreds >>>>>>of megahertz so I don't think it's because of slow switching. >>>>>> >>>>>>I measured the current at point X and it seems high - over 100mA. >>>>>>Could this be the cause of the overheating? Even if it isn't the >>>>>>problem >>>>>>it seems wasteful. I tried putting in a resistor there but the circuit >>>>>>shuts down. >>>>>>. >>>>>>I also tried a honking big "high speed switching" transistor pulled >>>>>>out of a PSU but it made the LEDs go very dim. >>>>>> >>>>>>Any ideas? >>>>> >>>>>That's a horrible circuit. Too many conflicting parameters depend on >>>>>the value of R1. A proper blocking oscillator uses an RC time constant >>>>>to set the rep rate, and a separate resistor to limit the base >>>>>current. >>>>> >>>>>ftp://jjlarkin.lmi.net/BlockOsc.JPG >>>> >>>>Would you care to provide some sample values and analyze that circuit >>>>for us? >>> >>>No, too much work. >> >>Hmm. >> >>Just to goose things along, for the joule thief circuit I get >>something like this for the frequency: >> >> (Vbattery - Vsat) * (Vout + Vfreewheeldiode - Vbattery) >>f = ------------------------------------------------------- >> Ic_peak * L_collector * (Vout + Vfreewheeldiode - Vsat) >> >>Ic_peak may require an iteration or two with a datasheet to >>approximate. I just go in with an assumed Ic, look up a beta estimate >>for that on one curve and then grab the Vbe estimate from another >>curve, and apply them into: >> >>Ic_peak = beta*(Nratio*(Vbattery - Vsat) + Vbattery - Vbe))/Rbase >> >>That Ic_peak is then used to repeat the process. When it settles, >>I've usually got a reasonable figure that I can use to compute 'f'. >>(Nratio is the turns ratio, usually just 1.) I tend to use Vsat=0.2V. >> >>If your suggestion is so nicely designable, can't you at least provide >>an approximate equation? >> >>>>I see the RC node moving towards a bias point, but not really >>>>setting the frequency at which the BJT goes on and off. But I haven't >>>>sat down more than to glance over it, yet. >>> >>>In general, "on" pulse width is set by the volt-second saturation of >>>the inductor (although a small value of C can make it shorter.) >> >>So in your circuit case, it does depend on saturation of the core. >>What would happen in an air core case? > >The classic tube "blocking oscillator" had its ON time determined by >inductor saturation. If it can't saturate, the ON interval ends when >the transistor runs out of beta (or the tube out of plate current), or >when C runs out of charge to drive the base/grid. The "blocking" part >was the negative swing on the tube grid from grid current charging the >cap; it fired again when R1 charged the grid the other way, back to >the turnon threshold. > >> >>>Base >>>current is limited by R2 (the one connected to the base.) While the >>>transistor's on, the base current charges up the cap, and that charge >>>will back-bias the transistor until R1 recharges the cap back up to >>>+0.7 volts, at which it fires again. >>> >>>Something like that. >>> >>>Try R1=1K, R2=100 C=100nF as very rough starting points. A lot depends >>>on the inductor. It won't Spice unless the model includes inductor >>>saturation. >> >>Yes. I gather. > >Unless L can't saturate, of course. Then it's not an official >"blocking oscillator."Are the saturation of cores more predictable than BJT beta -- keeping in mind that we are talking about the same part number AND manufacturer in both cases?>>>It's probebly easier to use a Tiny Logic schmitt-trigger oscillator to >>>drive the transistor, and just use a single-winding inductor. Blocking >>>oscillators are tricky. >> >>Single BJTs are cheap and, if you saw one of the web sites mentioned >>some time back in the related thread, you'd have seen that the whole >>thing is tiny enough to place inside a small flashlight bulb base. > >If you don't mind the 2-winding coil, and the additional futzing, the >blocking oscillator is potentially cheap. > >> >>... >> >>Since you write, "That's a horrible circuit. Too many conflicting >>parameters depend on the value of R1. A proper blocking oscillator >>uses an RC time constant to set the rep rate, and a separate resistor >>to limit the base current," shouldn't it be the case that you can tell >>me how to compute the frequency with ease? Isn't that the entire >>point of saying all that? Or did I miss your point, here? > >As I said, a blocking oscillator is complex. I can't define the >frequency "with ease." But having separate control over base drive and >rep-rate helps orthogonalize things. Having one part control two >circuit parameters can get awkward. Three is a nightmare.But the existing schematic (the joule thief thing) does that, within bounds. Assuming fixed battery voltage and fixed winding ratio of the transformer, the base resistor sets the Ib. The beta then establishes the peak Ic. I'm not sure of any advantages in the new arrangement you suggest, yet. (And I suspect it's behavior is harder to analyze, besides.)>The MIT RadLab books are full of blocking oscillator theory and >circuits, especially vol 19. Tube radars were full of them, as >oscillators, comparators, pulse regenerators, and frequency dividers.I think someone posted some of that, some time back, in sci.electronics.design. I'll see if I can track any of that down. sadly, other than that possibility, I don't have ready access.>Some texts referred to rf squegging circuits as blocking oscillators.I'll look to see if I can find a lucid description. Thanks, Jon
