On 9/20/2021 7:06 PM, John Larkin wrote:> On Mon, 20 Sep 2021 17:45:12 -0400, bitrex <user@example.net> wrote: > >> Is it possible to take your standard Baxandall and tap the capacitor, >> take an aux winding off the secondary and feed a somewhat higher DC >> voltage to the cap (through the usual two-diode supply handoff >> arrangement), and use it to feed the gate drive to the transistors as >> well, which would be clocked rather than self-oscillating. >> >> The goal would be to have a quiet step-up converter that could do say 5 >> to ~150 in one step, or maybe with a single multiplier stage. That seems >> hard to do with anything off the shelf as compact pulse transformers >> with the appropriate turns ratio don't seem to be really available, you >> get into CFL-type transformers whose ratios are too large, but there >> might be something appropriate with a third winding to bootstrap the >> primary swing > > Lotta words. Got a sketch? >I don't think the idea is worth sketching up, yes you can boostrap a resonant converter off its own output in various ways and get it to swing harder into the primary. Unfortunately it looks to me like this always has the downside of ruining the "resonant" part, the resonant frequency isn't well-defined anymore and it runs more like a blocking oscillator.
Turbo Royer/Baxandall in boost configuration
Started by ●September 20, 2021
Reply by ●September 21, 20212021-09-21
Reply by ●September 21, 20212021-09-21
On 9/20/2021 9:04 PM, Anthony William Sloman wrote:> On Tuesday, September 21, 2021 at 9:05:38 AM UTC+10, bitrex wrote: >> On 9/20/2021 6:50 PM, Lasse Langwadt Christensen wrote: >>> mandag den 20. september 2021 kl. 23.53.07 UTC+2 skrev bitrex: >>>> On 9/20/2021 5:45 PM, bitrex wrote: >>>>> Is it possible to take your standard Baxandall and tap the capacitor, >>>>> take an aux winding off the secondary and feed a somewhat higher DC >>>>> voltage to the cap (through the usual two-diode supply handoff >>>>> arrangement), and use it to feed the gate drive to the transistors as >>>>> well, which would be clocked rather than self-oscillating. >>>>> >>>>> The goal would be to have a quiet step-up converter that could do say 5 >>>>> to ~150 in one step, or maybe with a single multiplier stage. That seems >>>>> hard to do with anything off the shelf as compact pulse transformers >>>>> with the appropriate turns ratio don't seem to be really available, you >>>>> get into CFL-type transformers whose ratios are too large, but there >>>>> might be something appropriate with a third winding to bootstrap the >>>>> primary swing >>>> Even if I really wanted to roll my own transformers the require ratio of >>>> something like 47u to 4.7m is annoying to do by hand on some common >>>> compact ferrite toroid like an FT50-43, and multiple multiplier stages >>>> start to suck efficiency pretty quickly >>> >>> isn't a transformer like used in USB chargers right around the right voltages when run in reverse? >>> >>> https://dk.rs-online.com/web/p/transformer-switch-mode-stromforsyning-smps/4185470/ >>> >> This is a cheesy 1 transistor boost, works OK and I can wind the coil on >> a FT50-43 in a few minutes. Efficiency is bad, almost 1/2 watt in the >> base resistor :((( > It's totally revolting. With only one transistor is isn't even a Royer inverter, and the simulation doesn't suggest that it is actually resonant. > > That doesn't mean that it won't work, and I suppose it could solve your problem. But all the waveforms are horribly spikey. Not attractive. >Just realized that the .asc isn't the same as the imgur link, it was so revolting I guess I forgot to save it
Reply by ●September 21, 20212021-09-21
On a sunny day (Mon, 20 Sep 2021 17:45:12 -0400) it happened bitrex <user@example.net> wrote in <Jh72J.114246$Kv2.67276@fx47.iad>:>Is it possible to take your standard Baxandall and tap the capacitor, >take an aux winding off the secondary and feed a somewhat higher DC >voltage to the cap (through the usual two-diode supply handoff >arrangement), and use it to feed the gate drive to the transistors as >well, which would be clocked rather than self-oscillating. > >The goal would be to have a quiet step-up converter that could do say 5 >to ~150 in one step, or maybe with a single multiplier stage. That seems >hard to do with anything off the shelf as compact pulse transformers >with the appropriate turns ratio don't seem to be really available, you >get into CFL-type transformers whose ratios are too large, but there >might be something appropriate with a third winding to bootstrap the >primary swingHigh ratio transformers are easy with UI or E cores I wind the small ones with thin seundary on the dremel... Just count... http://panteltje.com/pub/home_made_1_to_33_hv_transformer_img_3096.jpg 12V DC to approx 440 Vpp 20 to 44 kHz: http://panteltje.com/pub/ultrasonic_antifouling_bigger_transformer_IMG_5179.JPG http://panteltje.com/pub/ultrasonic_anti_fouling_test_board_IMG_5135.JPG Not to mention all the TV high voltage flyback stuff.. and what a little BC107 or so can do: http://panteltje.com/pub/new_transformer_test_setup_img_3153.jpg Have no fear of transformers.... http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg This uses a standard 1:10 audio? transformer flyback to power a GMtube: http://panteltje.com/panteltje/pic/gm_pic2/ seems quiet.... Even has GPS so many projects with transformers...
Reply by ●September 21, 20212021-09-21
On 9/21/2021 2:32 AM, Jan Panteltje wrote:> On a sunny day (Mon, 20 Sep 2021 17:45:12 -0400) it happened bitrex > <user@example.net> wrote in <Jh72J.114246$Kv2.67276@fx47.iad>: > >> Is it possible to take your standard Baxandall and tap the capacitor, >> take an aux winding off the secondary and feed a somewhat higher DC >> voltage to the cap (through the usual two-diode supply handoff >> arrangement), and use it to feed the gate drive to the transistors as >> well, which would be clocked rather than self-oscillating. >> >> The goal would be to have a quiet step-up converter that could do say 5 >> to ~150 in one step, or maybe with a single multiplier stage. That seems >> hard to do with anything off the shelf as compact pulse transformers >> with the appropriate turns ratio don't seem to be really available, you >> get into CFL-type transformers whose ratios are too large, but there >> might be something appropriate with a third winding to bootstrap the >> primary swing > > High ratio transformers are easy with UI or E cores > I wind the small ones with thin seundary on the dremel... > Just count... > http://panteltje.com/pub/home_made_1_to_33_hv_transformer_img_3096.jpg > > 12V DC to approx 440 Vpp 20 to 44 kHz: > http://panteltje.com/pub/ultrasonic_antifouling_bigger_transformer_IMG_5179.JPG > http://panteltje.com/pub/ultrasonic_anti_fouling_test_board_IMG_5135.JPG > > Not to mention all the TV high voltage flyback stuff.. > and what a little BC107 or so can do: > http://panteltje.com/pub/new_transformer_test_setup_img_3153.jpg > > Have no fear of transformers.... > http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg > http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg > > This uses a standard 1:10 audio? transformer flyback to power a GMtube: > http://panteltje.com/panteltje/pic/gm_pic2/ > seems quiet.... Even has GPS > > so many projects with transformers... >Here's a one transistor oscillator that might be worth experimenting with more. Instead of trying to bootstrap it from the secondary, speed the whole thing up to several hundred kHz, to bring the required primary inductance down. Then use an aux winding to apply negative feedback to the supply rail to whip that sine into shape: <https://imgur.com/a/MgBWVDq> Version 4 SHEET 1 1148 680 WIRE -320 -752 -416 -752 WIRE -144 -752 -320 -752 WIRE 112 -752 -80 -752 WIRE 208 -752 112 -752 WIRE 288 -752 208 -752 WIRE 432 -752 352 -752 WIRE 560 -752 432 -752 WIRE 704 -752 560 -752 WIRE 208 -656 208 -752 WIRE 432 -656 432 -752 WIRE 704 -656 704 -752 WIRE 560 -640 560 -752 WIRE -320 -624 -320 -752 WIRE 0 -624 -320 -624 WIRE -592 -576 -592 -624 WIRE 112 -496 112 -752 WIRE 112 -496 -112 -496 WIRE 208 -496 208 -592 WIRE 432 -496 432 -576 WIRE 560 -496 560 -576 WIRE 704 -496 704 -576 WIRE -592 -448 -592 -496 WIRE 480 -384 320 -384 WIRE 784 -384 544 -384 WIRE 912 -384 784 -384 WIRE 1056 -384 912 -384 WIRE -112 -352 -112 -496 WIRE 0 -352 0 -624 WIRE 112 -336 112 -496 WIRE 400 -288 224 -288 WIRE 480 -288 400 -288 WIRE 784 -288 784 -384 WIRE 784 -288 544 -288 WIRE -112 -272 -592 -272 WIRE 224 -240 224 -288 WIRE 784 -224 784 -288 WIRE 912 -160 912 -384 WIRE 1056 -128 1056 -384 WIRE 0 -96 0 -272 WIRE 0 -96 -208 -96 WIRE 112 -96 112 -272 WIRE 112 -96 0 -96 WIRE 224 -96 224 -160 WIRE 320 -96 320 -384 WIRE 320 -96 224 -96 WIRE 784 -96 784 -160 WIRE 784 -96 320 -96 WIRE -448 -64 -512 -64 WIRE -320 -64 -384 -64 WIRE 784 -32 784 -96 WIRE -208 0 -208 -96 WIRE 400 32 400 -288 WIRE 480 32 400 32 WIRE 608 32 544 32 WIRE -592 48 -592 -272 WIRE -512 48 -512 -64 WIRE -512 48 -592 48 WIRE -464 48 -512 48 WIRE -320 48 -320 -64 WIRE -320 48 -384 48 WIRE -272 48 -320 48 WIRE 320 128 320 -96 WIRE 480 128 320 128 WIRE 608 128 608 32 WIRE 608 128 544 128 WIRE 784 128 784 32 WIRE 784 128 608 128 WIRE 912 128 912 -96 WIRE 912 128 784 128 WIRE 1056 128 1056 -48 WIRE 1056 128 912 128 WIRE 784 160 784 128 WIRE 784 176 784 160 WIRE -208 208 -208 96 WIRE 784 272 784 240 FLAG -416 -752 +5 IOPIN -416 -752 In FLAG -208 208 0 FLAG -592 -448 0 FLAG -592 -624 +5 IOPIN -592 -624 Out FLAG 784 272 0 FLAG 208 -496 0 FLAG 704 -496 0 FLAG 432 -496 0 FLAG 560 -496 0 SYMBOL ind2 16 -368 M0 WINDOW 3 -49 82 Left 2 SYMATTR InstName L1 SYMATTR Value 4.7� SYMBOL ind2 240 -256 M0 SYMATTR InstName L2 SYMATTR Value 2.2m SYMBOL ind2 -128 -256 M180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L3 SYMATTR Value 1� SYMBOL npn -272 0 R0 SYMATTR InstName Q1 SYMATTR Value 2SCR553P SYMBOL cap 128 -272 R180 WINDOW 0 24 56 Left 2 WINDOW 3 -86 38 Left 2 SYMATTR InstName C1 SYMATTR Value 0.47� SYMBOL res -368 32 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 2.2k SYMBOL cap -384 -80 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C2 SYMATTR Value 0.1� SYMBOL voltage -592 -592 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL cap 768 -32 R0 SYMATTR InstName C3 SYMATTR Value 0.1� SYMBOL res 768 144 R0 SYMATTR InstName R1 SYMATTR Value 1Meg SYMBOL current 1056 -128 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName I1 SYMATTR Value 0.005 SYMBOL cap 768 -224 R0 SYMATTR InstName C4 SYMATTR Value 0.1� SYMBOL cap 896 -160 R0 SYMATTR InstName C5 SYMATTR Value 0.47� SYMBOL schottky -144 -736 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D5 SYMATTR Value 1N5817 SYMATTR Description Diode SYMATTR Type diode SYMBOL cap 192 -656 R0 SYMATTR InstName C6 SYMATTR Value 4.7� SYMBOL ind2 688 -560 M180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L4 SYMATTR Value 470� SYMBOL schottky 352 -768 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName D6 SYMATTR Value 1N5817 SYMATTR Description Diode SYMATTR Type diode SYMBOL schottky 480 -368 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D1 SYMATTR Value 1N5817 SYMATTR Description Diode SYMATTR Type diode SYMBOL schottky 480 -272 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D2 SYMATTR Value 1N5817 SYMATTR Description Diode SYMATTR Type diode SYMBOL schottky 544 16 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName D3 SYMATTR Value 1N5817 SYMATTR Description Diode SYMATTR Type diode SYMBOL schottky 544 112 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName D4 SYMATTR Value 1N5817 SYMATTR Description Diode SYMATTR Type diode SYMBOL res 416 -672 R0 SYMATTR InstName R2 SYMATTR Value 10k SYMBOL cap 544 -640 R0 SYMATTR InstName C7 SYMATTR Value 0.047� TEXT -632 472 Left 2 !.tran 5m startup uic TEXT -712 -360 Left 2 !K L1 L2 L3 L4 0.99
Reply by ●September 21, 20212021-09-21
On a sunny day (Tue, 21 Sep 2021 02:55:18 -0400) it happened bitrex <user@example.net> wrote in <rlf2J.13646$d82.5695@fx21.iad>:>On 9/21/2021 2:32 AM, Jan Panteltje wrote: >> On a sunny day (Mon, 20 Sep 2021 17:45:12 -0400) it happened bitrex >> <user@example.net> wrote in <Jh72J.114246$Kv2.67276@fx47.iad>: >> >>> Is it possible to take your standard Baxandall and tap the capacitor, >>> take an aux winding off the secondary and feed a somewhat higher DC >>> voltage to the cap (through the usual two-diode supply handoff >>> arrangement), and use it to feed the gate drive to the transistors as >>> well, which would be clocked rather than self-oscillating. >>> >>> The goal would be to have a quiet step-up converter that could do say 5 >>> to ~150 in one step, or maybe with a single multiplier stage. That seems >>> hard to do with anything off the shelf as compact pulse transformers >>> with the appropriate turns ratio don't seem to be really available, you >>> get into CFL-type transformers whose ratios are too large, but there >>> might be something appropriate with a third winding to bootstrap the >>> primary swing >> >> High ratio transformers are easy with UI or E cores >> I wind the small ones with thin seundary on the dremel... >> Just count... >> http://panteltje.com/pub/home_made_1_to_33_hv_transformer_img_3096.jpg >> >> 12V DC to approx 440 Vpp 20 to 44 kHz: >> http://panteltje.com/pub/ultrasonic_antifouling_bigger_transformer_IMG_5179.JPG >> http://panteltje.com/pub/ultrasonic_anti_fouling_test_board_IMG_5135.JPG >> >> Not to mention all the TV high voltage flyback stuff.. >> and what a little BC107 or so can do: >> http://panteltje.com/pub/new_transformer_test_setup_img_3153.jpg >> >> Have no fear of transformers.... >> http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg >> http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg >> >> This uses a standard 1:10 audio? transformer flyback to power a GMtube: >> http://panteltje.com/panteltje/pic/gm_pic2/ >> seems quiet.... Even has GPS >> >> so many projects with transformers... >> > >Here's a one transistor oscillator that might be worth experimenting >with more. Instead of trying to bootstrap it from the secondary, speed >the whole thing up to several hundred kHz, to bring the required primary >inductance down. Then use an aux winding to apply negative feedback to >the supply rail to whip that sine into shape: > ><https://imgur.com/a/MgBWVDq>I see it does not boost the supply, L1 is always on the +5, but raises the bias current to the transistor base via L3 R3 perhaps when C6 goes above that +5. No sure that is a good idea, The other secundary is just a bridge rectifier, sort of a double Villard circuit perhaps. Peculiar. As to the tuned one transistor sine wave converter, used that many times in the old days, for example for EPROM programmer http://panteltje.com/pub/tuned_eprom_programmer_voltage_generator.gif from this: http://panteltje.com/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_inside2_img_1757.jpg thing still works.. You can make it any frequency you want depending on the transistor, diode and core of course. But all those RF carriers..... If you have a Microchip PIC available some have a build in PWM generator and a comparator that works directly on the PWM so you can have cycle by cycle current limit etc etc. http://panteltje.com/pub/power_pic/power_pic_synchronous_rectifier_working_img_0965.jpg you can see the small current transformer at the bottom in red wire from the drain of the MOSFET. http://panteltje.com/panteltje/pic/pwr_pic/ been in use now since 2008 12 hours a day... There is more... Lots of stuff on ebay, have a 5V to 300 kV converter (more like 30kV in reality) and http://panteltje.com/pub/inductive_coupling_real_power_300Vpp_IMG_6092.JPG with those Chinese induction things: http://panteltje.com/pub/crucible_with_molten_solder_IMG_5439.JPG later...
Reply by ●September 21, 20212021-09-21
On Tue, 21 Sep 2021 06:32:35 GMT, Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:>On a sunny day (Mon, 20 Sep 2021 17:45:12 -0400) it happened bitrex ><user@example.net> wrote in <Jh72J.114246$Kv2.67276@fx47.iad>: > >>Is it possible to take your standard Baxandall and tap the capacitor, >>take an aux winding off the secondary and feed a somewhat higher DC >>voltage to the cap (through the usual two-diode supply handoff >>arrangement), and use it to feed the gate drive to the transistors as >>well, which would be clocked rather than self-oscillating. >> >>The goal would be to have a quiet step-up converter that could do say 5 >>to ~150 in one step, or maybe with a single multiplier stage. That seems >>hard to do with anything off the shelf as compact pulse transformers >>with the appropriate turns ratio don't seem to be really available, you >>get into CFL-type transformers whose ratios are too large, but there >>might be something appropriate with a third winding to bootstrap the >>primary swing > >High ratio transformers are easy with UI or E cores >I wind the small ones with thin seundary on the dremel... >Just count... > http://panteltje.com/pub/home_made_1_to_33_hv_transformer_img_3096.jpg > >12V DC to approx 440 Vpp 20 to 44 kHz: > http://panteltje.com/pub/ultrasonic_antifouling_bigger_transformer_IMG_5179.JPG > http://panteltje.com/pub/ultrasonic_anti_fouling_test_board_IMG_5135.JPG > >Not to mention all the TV high voltage flyback stuff.. >and what a little BC107 or so can do: > http://panteltje.com/pub/new_transformer_test_setup_img_3153.jpg > >Have no fear of transformers.... > http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg > http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg > >This uses a standard 1:10 audio? transformer flyback to power a GMtube: > http://panteltje.com/panteltje/pic/gm_pic2/ >seems quiet.... Even has GPS > >so many projects with transformers...Transformers are wonderful, as long as you don't wind them. You can easily turn a 2-minute 50-cent part into 1000x those numbers. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it.
Reply by ●September 21, 20212021-09-21
On Mon, 20 Sep 2021 17:59:22 -0700 (PDT), sea moss <danluster81@gmail.com> wrote: <snip>>But then I thought, maybe the active-clamp forward would work for you too. Try one of the transformers Lasse recommended. I cannot immediately see anything wrong with doing that... the active-clamp forward is nice since there is no reset winding needed, and the clamp capacitor soaks up the leakage energy making it one of the quieter isolated topologies. > >But like I said I am new to the topology so I cannot tell you if there are any subtleties to be careful with. Does anyone here have any insight into the active-clamp forward topology that I can't find in all the app notes? (not trying to hijack this thread)The active clamp isn't intended to 'absorb' leakage energy, but to recycle it. This is achieved if there's an energy path to the load during the clamping interval, as in a flyback circuit. In doing so, magnetizing energy can not only reset core flux, but reverse it, so that double core flux excursions are possible without core saturation. Core flux excursions that pass through zero are less lossy, in general. The same thing is possible with a forward converter, if synchronous rectification is present on the output. If the output rectifier is a self-driven or other kind of synchronous circuit, you can recover leakage energy to the load simply by adding a low power inductor (L~= to the main output choke). This also results in output ripple current cancelation. With reversing magnetizing current, you're set up for zero-voltage (or at least reduced voltage) switching, at a reduced switching loss. Under certain conditions, switch current can be negative at turn-on, depending on the magnitude of magnetizing current. In the 90s this was 'complicated' by lack of controller and driver circuitry - though the simple methods developed were in some ways superior to the integrated options available now. AD/LTC offer prepackaged models and simulations that run in LTspice ( eg ADP1074 , LT3765 ) which control both active clamp and synchronous rectifiers. RL
Reply by ●September 21, 20212021-09-21
On Mon, 20 Sep 2021 17:45:12 -0400, bitrex <user@example.net> wrote:>Is it possible to take your standard Baxandall and tap the capacitor, >take an aux winding off the secondary and feed a somewhat higher DC >voltage to the cap (through the usual two-diode supply handoff >arrangement), and use it to feed the gate drive to the transistors as >well, which would be clocked rather than self-oscillating. > >The goal would be to have a quiet step-up converter that could do say 5 >to ~150 in one step, or maybe with a single multiplier stage. That seems >hard to do with anything off the shelf as compact pulse transformers >with the appropriate turns ratio don't seem to be really available, you >get into CFL-type transformers whose ratios are too large, but there >might be something appropriate with a third winding to bootstrap the >primary swingHere is a sine oscillator. https://www.dropbox.com/s/wqygdxrcr2egxsv/AGC_Sine_Osc.jpg?raw-1 The output amplitude is very stable with time and temperature. The voltage at the collector is reliably 2xV+ p-p. I invented this when I was a kid, still in college. It was used in the Boresight Alignment Kit for the C5A. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it.
Reply by ●September 21, 20212021-09-21
...> Here is a sine oscillator. > > https://www.dropbox.com/s/wqygdxrcr2egxsv/AGC_Sine_Osc.jpg?raw-1 > > The output amplitude is very stable with time and temperature. The > voltage at the collector is reliably 2xV+ p-p. > > I invented this when I was a kid, still in college. It was used in the > Boresight Alignment Kit for the C5A. >...That configuration is usually known as a Reinartz oscillator. It has been commonly used as a self-oscillating mixer in transistor radios since the mid nineteen-fifties. In the common implementation the resonant tank is on the secondary rather than the collector to give some isolation from variation of transistor parameters and improve stability. https://www.electronics-notes.com/images/transistor-radio-self-oscillating-mixer-ferrite-rod-antenna.png kw
Reply by ●September 21, 20212021-09-21
On Tue, 21 Sep 2021 10:05:03 -0700 (PDT), "ke...@kjwdesigns.com" <keith@kjwdesigns.com> wrote:>... >> Here is a sine oscillator. >> >> https://www.dropbox.com/s/wqygdxrcr2egxsv/AGC_Sine_Osc.jpg?raw-1 >> >> The output amplitude is very stable with time and temperature. The >> voltage at the collector is reliably 2xV+ p-p. >> >> I invented this when I was a kid, still in college. It was used in the >> Boresight Alignment Kit for the C5A. >>... > >That configuration is usually known as a Reinartz oscillator. It has been commonly used as a self-oscillating mixer in transistor radios since the mid nineteen-fifties. > >In the common implementation the resonant tank is on the secondary rather than the collector to give some isolation from variation of transistor parameters and improve stability. > >https://www.electronics-notes.com/images/transistor-radio-self-oscillating-mixer-ferrite-rod-antenna.png > >kwMy circuit is clearly different. It's way simpler and has a built-in AGC system that precisely controls oscillation amplitude. I used it as the excitation for a Talyvel arc-second-resolution inclinometer, basically an LVDT on a pendulum. It was fun to work with. I tested it on a steel plate sitting on a 55-gallon drum full of rocks. I could see people walking around and flexing the concrete slab building. Hey, they still make them! https://scigate.com.sg/products/43-taylor-hobson/2661-electronic-levels-clinometers?pdt=true -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
