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How to select transistor for oscillator ?

Started by Unknown September 11, 2018
Suggestions: go figure it out. This is cookbook stuff and you are leaving out to many details.
On Wed, 12 Sep 2018 07:05:17 GMT, <698839253X6D445TD@nospam.org>
wrote:

>John Larkin wrote >>On Tue, 11 Sep 2018 20:57:34 GMT, <698839253X6D445TD@nospam.org> >>wrote: >> >>>John Larkin wrote >>>>I have some CK722's! >>>> >>>>https://www.dropbox.com/s/lq8w4jsh0sn5fc0/Ck722-0A.JPG?raw=1 >>> >>>What is the Ft? > >?? > > >>>>Here's my oscillator: >>>> >>>>https://www.dropbox.com/s/19imyfg1ubh2z3c/P5_CCRO.jpg?raw=1 >>>> >>>>The CCROs have TCs, Qs, and initial accuracies over 10x better than an >>>>LC. The higher-frequency parts have Qs in the thousands. >>> >>>Ceramics are not better than quartz crystals I think? >> >>They are available up into the GHz. As oscillators, they are a lot >>more pullable than crystals. > >How do you pull those?
I use a varicap. A CCRO is actually a shorted transmission line (and TDRs like one) but you can pretend it's a parallel LC.
> > >>But most CCROs are probably used as >>bandpass filters. >> >>http://www.mpdigest.com/2017/01/23/ceramic-resonator-band-pass-filter/ > > > >Yes of course, those ceramic filters, or should I say SAW filters, are everywhere, >for example in TVs as IF filter.
A CCRO is different from a SAW. And different from a mechanically resonant ceramic filter. I guess you knew that.
>But I meant for frequency stability, >for example these > http://panteltje.com/pub/5_dollar_LNB_PCB_IMG_3582.GIF >the greenish round things on the right are 9.75 GHz and 10.6 GHz oscillators (smallest one highest frequency), >but precisely the reason I am using the latest LNB with a crystal reference and a PLL >to get those same frequencies, as the crystal is much more stable, >even without temperature compensation. >This is needed to receive 10.4 GHz single sideband signals where a few hundred Hz at 10.4 GHz >makes the speech un-intelligible. >That is also where the Rubidium reference comes into play. >For less precise things such as some filters ceramics are OK, >those are also OK for local oscillator in LNBs for digital TV. >Important for all this in my case is that you can electronically adjust frequency, say pull the crystal, >so you can PLL lock to some reference. >Look at the feedback coupling of those oscillator transistors to the ceramic resonators: >( O ) >b c > >Microwave is fun ! >
I'm not very interested in sine waves or tuned circuits; we work in time domain. But lots of microwave parts work great off-label in pulse circuits. They'e just not well characterized for that. -- John Larkin Highland Technology, Inc lunatic fringe electronics
On Wed, 12 Sep 2018 06:23:49 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>On Tuesday, September 11, 2018 at 3:50:25 PM UTC-4, John Larkin wrote: >> On Tue, 11 Sep 2018 19:29:08 GMT, <698839253X6D445TD@nospam.org> >> wrote: >> >> >John Larkin wrote >> >>Bipolars are not unstable. But mosfets are usually easier to use. >> >> >> >>The last bipolar transistor circuit that I designed was in fact a >> >>Colpitts oscillator. It's a 600 MHz VCO that uses a coaxial ceramic >> >>resonator and a BFT25A. The time consuming bit was temperature >> >>compensating it; I wound up buying a reel of custom-brewed N4700 caps. >> > >> >I use bipolars all the time, >> >Here a 2.4 Giggle Hz oscillator: >> > http://panteltje.com/pub/2.4GHz_twisted_oscillator_IMG_3629.GIF >> > >> >1.57 Giggle Hertz: >> > http://panteltje.com/pub/GPS_jammer_board_twisted_wire_1.57GHz_oscillator_IMG_3622.GIF >> > >> >Think those were BFR91. >> >These are both to some degree frequency controlled by the base current, >> >that changes Vce and CVce and thus frequency. >> > >> >Anyways that was locked to the FPGA board that was locked to the Rubidium reference on the left. >> > http://panteltje.com/pub/25MHz_lock_test_setup_IMG_3721.GIF >> > >> >6 MHz xtal oscillator: >> > http://panteltje.com/pub/6MHz_xtal_oscillator.gif >> > >> >For lower frequencies I of course use unijunction transistors. >> > >> >For even higher frequencies there are 'sjips', like this I am working on: >> > http://panteltje.com/pub/octagon_twin_LNB_OTLSO_inside_RT320M_PLL_IMG_6538.JPG >> >The RT320M chip is a PLL locked to a 25 MHz xtal (on the right) with an output of >> >390 x 25 MHz = 9.750 GHz >> >or >> >426 x 25 MHz = 10.650 GHz >> >used as local oscillator and mixer for 10.7 GHz to 12,75 GHz reception. >> >Modifying it for 10.4 GHz, >> > >> >Removed the crystal from the board, here testing if it still works with crystal on thin wires on the side. >> >Thing is small... bad PCB, tracks fall off... >> >A tunable external reference will be connected via a connector on the bottom. >> > http://panteltje.com/pub/octagon_LNB_crystal_removed_IMG_6546.JPG >> > >> >Will attempt that locking thing with this LNB too. >> > >> >For even higher frequencies I have some various color lasers. >> > >> >:-) >> > >> > >> >But anyways bipolars are great, the naming here in Elektor magazine was TUP and TUN for >> >Transistor Universal NPN and Transistor Universal PNP, >> >BC547 BC557, also known in a smaller package as >> >BC847 BC857 >> >have only a Ft of 100 MHz or so, good enough for most things. >> > >> >I also still have an old germanium OC76 and an OC140 germanium transistor in black painted glass envelope. >> > http://panteltje.com/pub/old_germanium_transistors_IMG_6554.JPG >> >> I have some CK722's! >> >> https://www.dropbox.com/s/lq8w4jsh0sn5fc0/Ck722-0A.JPG?raw=1 >> >> and some high-voltage opamps >> >> https://www.dropbox.com/s/st1upzhqkil8bp6/Philbricks.jpg?raw=1 >I've got a tray full of HV opamps from Apex (PA341). Too noisy for me >but if anyone wants some drop me a line. > >Maybe I should try ebay? > >George H.
Apex used to use an AT&T HV cmos fab process that made possibly the noisiest transistors ever invented. Nowadays they just put parts on boards and charge a lot. -- John Larkin Highland Technology, Inc lunatic fringe electronics
John Larkin wrote
>On Wed, 12 Sep 2018 07:05:17 GMT, <698839253X6D445TD@nospam.org> >wrote: > >>John Larkin wrote >>>On Tue, 11 Sep 2018 20:57:34 GMT, <698839253X6D445TD@nospam.org> >>>wrote: >>> >>>>John Larkin wrote >>>>>I have some CK722's! >>>>> >>>>>https://www.dropbox.com/s/lq8w4jsh0sn5fc0/Ck722-0A.JPG?raw=1 >>>> >>>>What is the Ft? >> >>??
OK, you don't know, it seems, or overlooked the question. I looked up the Ft of my OC76 and it is listed as 1 MHz. Those early Ge transistors were usually slow, that is why I asked.
>>>>>Here's my oscillator: >>>>> >>>>>https://www.dropbox.com/s/19imyfg1ubh2z3c/P5_CCRO.jpg?raw=1 >>>>> >>>>>The CCROs have TCs, Qs, and initial accuracies over 10x better than an >>>>>LC. The higher-frequency parts have Qs in the thousands. >>>> >>>>Ceramics are not better than quartz crystals I think? >>> >>>They are available up into the GHz. As oscillators, they are a lot >>>more pullable than crystals. >> >>How do you pull those? > >I use a varicap. A CCRO is actually a shorted transmission line (and >TDRs like one) but you can pretend it's a parallel LC.
Aha, yes, cool.
>>>But most CCROs are probably used as >>>bandpass filters. >>> >>>http://www.mpdigest.com/2017/01/23/ceramic-resonator-band-pass-filter/ >> >> >> >>Yes of course, those ceramic filters, or should I say SAW filters, are everywhere, >>for example in TVs as IF filter.
>A CCRO is different from a SAW. And different from a mechanically >resonant ceramic filter. I guess you knew that.
No, I do not know everything :-) Looks in that picture like just some ceramic tubes like you add crystals together to make a steep filter.. Something vibrates mechanically... Any papers on that?
>>Microwave is fun ! >> > >I'm not very interested in sine waves or tuned circuits; we work in >time domain. But lots of microwave parts work great off-label in pulse >circuits. They'e just not well characterized for that.
Yes, some transformers will, diodes... But filters.. if it has high Q then it will show something like this: | || ||| || | damped oscillations. At those high frequencies any piece of wire is one or more wavelength long. So if you are into making fast pulses... of one or one half period, does not seem that easy to me. I have no experience with that at those frequencies, never needed it. That is why to me that RafaelMicro RT320M is so fascinating, and also that RTL-SDR stick, the R320M a complete PLL oscillator and mixer at 9.76 and 10.6 GHz, and the USB stick a complete receiver up to 1.7 GHz with IQ outputs, The length of the wires in the chip sort of overcomes the wavelength problem - is much much smaller than a wavelength. But the sign on the wall is that smaller on chip integration is the future. What is the fastest, I mean shortest, pulse you can make? How much power does it deliver?
On Wed, 12 Sep 2018 16:49:24 GMT, <698839253X6D445TD@nospam.org>
wrote:

>John Larkin wrote >>On Wed, 12 Sep 2018 07:05:17 GMT, <698839253X6D445TD@nospam.org> >>wrote: >> >>>John Larkin wrote >>>>On Tue, 11 Sep 2018 20:57:34 GMT, <698839253X6D445TD@nospam.org> >>>>wrote: >>>> >>>>>John Larkin wrote >>>>>>I have some CK722's! >>>>>> >>>>>>https://www.dropbox.com/s/lq8w4jsh0sn5fc0/Ck722-0A.JPG?raw=1 >>>>> >>>>>What is the Ft? >>> >>>?? > >OK, you don't know, it seems, or overlooked the question. >I looked up the Ft of my OC76 and it is listed as 1 MHz. >Those early Ge transistors were usually slow, that is why I asked.
CK722 was slow, maybe under 1 MHz, but the data sheets didn't spec it. I think it was a nasty alloy-junction part.
> > >>>>>>Here's my oscillator: >>>>>> >>>>>>https://www.dropbox.com/s/19imyfg1ubh2z3c/P5_CCRO.jpg?raw=1 >>>>>> >>>>>>The CCROs have TCs, Qs, and initial accuracies over 10x better than an >>>>>>LC. The higher-frequency parts have Qs in the thousands. >>>>> >>>>>Ceramics are not better than quartz crystals I think? >>>> >>>>They are available up into the GHz. As oscillators, they are a lot >>>>more pullable than crystals. >>> >>>How do you pull those? >> >>I use a varicap. A CCRO is actually a shorted transmission line (and >>TDRs like one) but you can pretend it's a parallel LC. > >Aha, yes, cool. > > >>>>But most CCROs are probably used as >>>>bandpass filters. >>>> >>>>http://www.mpdigest.com/2017/01/23/ceramic-resonator-band-pass-filter/ >>> >>> >>> >>>Yes of course, those ceramic filters, or should I say SAW filters, are everywhere, >>>for example in TVs as IF filter. > >>A CCRO is different from a SAW. And different from a mechanically >>resonant ceramic filter. I guess you knew that. > >No, I do not know everything :-) >Looks in that picture like just some ceramic tubes like you add crystals together to make a steep filter.. >Something vibrates mechanically...
No, there is no motion. Each tube is a shorted coaxial transmission line. The dielectric constant of the ceramic is so high that the line is short relative to the round-trip frequency. In the filter, the CCRs are coupled somehow, classic multiple-resonator math. It's fun to TDR one. It looks just like a shorted coax, but the impedances are low, 10 ohms maybe, and there is a lot of delay relative to the size.
>Any papers on that?
Probably stuff from the manufacturers, although they usually work in frequency domain. Boring sine waves.
> > >>>Microwave is fun !
Pulses are even more fun!
>>> >> >>I'm not very interested in sine waves or tuned circuits; we work in >>time domain. But lots of microwave parts work great off-label in pulse >>circuits. They'e just not well characterized for that. > >Yes, some transformers will, diodes... >But filters.. if it has high Q then it will show something like this: > >| >|| >||| >|| >| >damped oscillations. >At those high frequencies any piece of wire is one or more wavelength long. > >So if you are into making fast pulses... of one or one half period, does not seem that easy to me. >I have no experience with that at those frequencies, never needed it.
There are cheap logic chips with rise times in the 100s of picoseconds. https://www.dropbox.com/s/7gajbmt923oesli/NC7SV74_2.JPG?raw=1
> >That is why to me that RafaelMicro RT320M is so fascinating, and also that RTL-SDR stick, >the R320M a complete PLL oscillator and mixer at 9.76 and 10.6 GHz, and the USB stick a complete receiver up to 1.7 GHz with IQ outputs, >The length of the wires in the chip sort of overcomes the wavelength problem - is much much smaller than a wavelength. >But the sign on the wall is that smaller on chip integration is the future. > >What is the fastest, I mean shortest, pulse you can make?
Step-recovery diodes can make sub 100 ps pulses easily. NLTLs can get down to rise times in the single digits of ps. Gain-switched lasers can make optical pulses in the 10s of ps width, from fairly slow electrical drive.
>How much power does it deliver?
Spark gaps can be impressive! -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Thursday, September 13, 2018 at 6:09:16 AM UTC+10, John Larkin wrote:
> On Wed, 12 Sep 2018 16:49:24 GMT, <698839253X6D445TD@nospam.org> > wrote: > > >John Larkin wrote > >>On Wed, 12 Sep 2018 07:05:17 GMT, <698839253X6D445TD@nospam.org> > >>wrote: > >> > >>>John Larkin wrote > >>>>On Tue, 11 Sep 2018 20:57:34 GMT, <698839253X6D445TD@nospam.org> > >>>>wrote: > >>>> > >>>>>John Larkin wrote
<snip>
> There are cheap logic chips with rise times in the 100s of > picoseconds. > > https://www.dropbox.com/s/7gajbmt923oesli/NC7SV74_2.JPG?raw=1
And slightly less cheap ECLinPS Plus parts (from ON Semiconductor) http://www.onsemi.com/PowerSolutions/productList.do?id=220 explicitly designed to drive 50R transmission lines (or 75R). <snip>
> Step-recovery diodes can make sub 100 ps pulses easily.
Not that easily. You do have to be careful about construction to minimise stray inductance and capacitance.
> NLTLs can get down to rise times in the single digits of ps. > > Gain-switched lasers can make optical pulses in the 10s of ps width, > from fairly slow electrical drive. > > >How much power does it deliver? > > Spark gaps can be impressive!
But erosive. And the glow-to-arc transition takes closer a microsecond than a picosecond. Getting an arc discharge involves getting the electrode surface hot enough that it can deform into atomically sharp spikes, sharp enough to deliver field emission. In the glow stage, positive ion bombardment knocks off secondary electrons and incidentally warms up the bombarded surface. -- Bill Sloman, Sydney
John Larkin wrote
>CK722 was slow, maybe under 1 MHz, but the data sheets didn't spec it. >I think it was a nasty alloy-junction part.
It took me half an hour googling to find the Ft of the OC76 online... Anyways I _do_ remember Philips had OC13 sold as LF transistor (for audio) and OC44 OC45 as 'IF' transistor for the 455 kHz or so IF amplifiers. RF GE transistors came later... in the sixties IIRC, I build a small FM transmitter with just 1 transistor also using the Cce change with voltage to frequency modulate it. Not sure that would work with a modern transistor. The old ones were so sensitive I did something this +9V /// | | dynamic mike (few hundred ohm) === |--- | ( | ) ( === tuned to about 100MHz | ( | | |------ | c | b | | e | | | | | /// | - R----- That thing was so sensitive you could here a clock ticking over the radio. The mike changed the Vce a few mV, was enough to get many kHz frequency deviation.
>>>>>But most CCROs are probably used as >>>>>bandpass filters. >>>>> >>>>>http://www.mpdigest.com/2017/01/23/ceramic-resonator-band-pass-filter/ >>>> >>>> >>>> >>>>Yes of course, those ceramic filters, or should I say SAW filters, are everywhere, >>>>for example in TVs as IF filter. >> >>>A CCRO is different from a SAW. And different from a mechanically >>>resonant ceramic filter. I guess you knew that. >> >>No, I do not know everything :-) >>Looks in that picture like just some ceramic tubes like you add crystals together to make a steep filter.. >>Something vibrates mechanically... > >No, there is no motion. Each tube is a shorted coaxial transmission >line. The dielectric constant of the ceramic is so high that the line >is short relative to the round-trip frequency. In the filter, the CCRs >are coupled somehow, classic multiple-resonator math.
Not sure I grab that, will look it up.
>It's fun to TDR one. It looks just like a shorted coax, but the >impedances are low, 10 ohms maybe, and there is a lot of delay >relative to the size. > > >>Any papers on that? > >Probably stuff from the manufacturers, although they usually work in >frequency domain. Boring sine waves.
The whole world uses sine waves to commie-nuke-aid....
>>>>Microwave is fun ! > >Pulses are even more fun!
Yea digital, but even there it is deliberately bandwidth limited, to get more info over the same link, in the same bandwidth, that is an art too. For those who try the laser fusion perhaps... but that did not work out so well either? Still waiting for usable break even. Most stuff uses sine waves.... Spectra...
>There are cheap logic chips with rise times in the 100s of >picoseconds. > >https://www.dropbox.com/s/7gajbmt923oesli/NC7SV74_2.JPG?raw=1
Na yaa, 100 ps is only 10 GHz.... so rise and fall times are much faster /\ /\ / \/ \ | | 100 ps period time | | 50 ps up, 50 ps down This one works at > 12 GHz... ;-)
>Step-recovery diodes can make sub 100 ps pulses easily. NLTLs can get >down to rise times in the single digits of ps. > >Gain-switched lasers can make optical pulses in the 10s of ps width, >from fairly slow electrical drive. > >>How much power does it deliver? > >Spark gaps can be impressive!
Yea, I did that as a kid, when I asked the son of a local radio ham to ask his father to listen for my 'transmitter' I did not get friendly feedback... 'If I ever hear that thing [again?] I will...' We had a lot of TV interference from things with electric ignition driving past the house, local TV was at about 65 MHz.. Only later did they use screened ignition cables and some measures against RF radiation.
On Wednesday, September 12, 2018 at 8:04:55 PM UTC-7, bill....@ieee.org wrote:
> On Thursday, September 13, 2018 at 6:09:16 AM UTC+10, John Larkin wrote:
> > Spark gaps can be impressive! > > But erosive. And the glow-to-arc transition takes closer a microsecond than a picosecond.
Erosion is real; there's a molybdenum electrode with a few grams missing in my junk box. The platinum button in a spark plug, though, lasts quite a while with modest currents. Probably the metal ions just aren't part of that kind of arc.
whit3rd <whit3rd@gmail.com> wrote in news:8c742c2a-2bfb-4e62-aca6-
b37506b44acc@googlegroups.com:

> The platinum button in a spark plug, though, lasts quite a while > with modest currents.
Buy a set of points for an old V8 chevy OR even a Briggs and Stratton lawn mower engine. Platinum plated contacts made for the purpose.
On Thu, 13 Sep 2018 01:32:15 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

>On Wednesday, September 12, 2018 at 8:04:55 PM UTC-7, bill....@ieee.org wrote: >> On Thursday, September 13, 2018 at 6:09:16 AM UTC+10, John Larkin wrote: > >> > Spark gaps can be impressive! >> >> But erosive. And the glow-to-arc transition takes closer a microsecond than a picosecond. > >Erosion is real; there's a molybdenum electrode with a few grams missing >in my junk box. The platinum button in a spark plug, though, lasts quite a while >with modest currents. Probably the metal ions just aren't part of that kind of arc.
Does anybody know what this is? https://www.dropbox.com/s/np4s7ifgg5f4gbz/DSC01841.JPG?raw=1 https://www.dropbox.com/s/6ckipx3z8v4nf72/DSC01844.JPG?raw=1 Spark gap? Waveguide T/R switch? -- John Larkin Highland Technology, Inc lunatic fringe electronics