Turbo Royer/Baxandall in boost configuration (2023 Update)

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?

Oh yeah....one of those in reverse might work....

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 :(((

<Version 4 SHEET 1 880 680 WIRE 400 -256 320 -256 WIRE 608 -256 464 -256 WIRE 768 -256 608 -256 WIRE 336 -112 256 -112 WIRE 400 -112 336 -112 WIRE 608 -112 608 -256 WIRE 608 -112 464 -112 WIRE 288 -32 256 -32 WIRE 320 -32 320 -256 WIRE 320 -32 288 -32 WIRE 768 -32 768 -256 WIRE 608 -16 608 -112 WIRE 48 0 -64 0 WIRE 160 0 48 0 WIRE 336 48 336 -112 WIRE 400 48 336 48 WIRE 528 48 464 48 WIRE -560 64 -560 16 WIRE -240 80 -320 80 WIRE -128 80 -176 80 WIRE -64 144 -64 0 WIRE 48 144 48 0 WIRE 160 144 160 0 WIRE 288 144 288 -32 WIRE 400 144 288 144 WIRE 528 144 528 48 WIRE 528 144 464 144 WIRE 608 144 608 48 WIRE 608 144 528 144 WIRE 768 144 768 48 WIRE 768 144 608 144 WIRE -560 192 -560 144 WIRE -320 192 -320 80 WIRE -256 192 -320 192 WIRE -128 192 -128 80 WIRE -128 192 -176 192 WIRE 608 192 608 144 WIRE 400 224 256 224 WIRE 608 304 608 272 WIRE 48 336 48 208 WIRE 160 336 160 224 WIRE 160 336 48 336 WIRE 208 336 160 336 WIRE 256 336 256 304 WIRE 256 336 208 336 WIRE -64 352 -64 240 WIRE 208 384 208 336 WIRE 208 384 144 384 WIRE -320 464 -320 192 WIRE 400 464 400 224 WIRE 400 464 -320 464 FLAG 144 384 +5 IOPIN 144 384 In FLAG -64 352 0 FLAG -560 192 0 FLAG -560 16 +5 IOPIN -560 16 Out FLAG 608 304 0 SYMBOL ind2 144 240 M180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L1 SYMATTR Value 47µ SYMBOL ind2 272 -128 M0 SYMATTR InstName L2 SYMATTR Value 1m SYMBOL ind2 272 208 M0 SYMATTR InstName L3 SYMATTR Value 4.7µ SYMBOL npn -128 144 R0 SYMATTR InstName Q1 SYMATTR Value 2SCR552P SYMBOL cap 32 144 R0 SYMATTR InstName C1 SYMATTR Value 0.1µ SYMBOL res -160 176 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 680 SYMBOL cap -176 64 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C2 SYMATTR Value 0.022µ SYMBOL voltage -560 48 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL diode 400 -96 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D1 SYMATTR Value MURS120 SYMBOL diode 400 -240 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D2 SYMATTR Value MURS120 SYMBOL diode 464 64 M270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D3 SYMATTR Value MURS120 SYMBOL diode 464 160 M270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D4 SYMATTR Value MURS120 SYMBOL cap 592 -16 R0 SYMATTR InstName C3 SYMATTR Value 0.47µ SYMBOL res 592 176 R0 SYMATTR InstName R1 SYMATTR Value 1Meg SYMBOL current 768 -32 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName I1 SYMATTR Value 0.005 TEXT -632 472 Left 2 !.tran 0.01 startup uic TEXT 112 -184 Left 2 !K L1 L2 L3 0.95

Lotta words. Got a sketch?

Buy yourself a simple winding machine with a turns-counter. They were pretty cheap when I last looked.

Or ask Winfield Hill if he knows of a small coil-winding shop near you. Academics are into one-offs for specific gear for specific experiments.

I was gonna take a look at your Spice model, but I am currently digesting the active-clamp forward topology (off the clock) so why look at yet another power converter circuit?

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)

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.

On a sunny day (Mon, 20 Sep 2021 17:45:12 -0400) it happened bitrex snipped-for-privacy@example.net wrote in <Jh72J.114246$ snipped-for-privacy@fx47.iad:

High ratio transformers are easy with UI or E cores I wind the small ones with thin seundary on the dremel... Just count...

12V DC to approx 440 Vpp 20 to 44 kHz: Not to mention all the TV high voltage flyback stuff.. and what a little BC107 or so can do: Have no fear of transformers.... This uses a standard 1:10 audio? transformer flyback to power a GMtube: 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:

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 4.7µ 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 1µ 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 0.47µ 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 0.1µ 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 0.1µ 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 0.1µ SYMBOL cap 896 -160 R0 SYMATTR InstName C5 SYMATTR Value 0.47µ 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 4.7µ SYMBOL ind2 688 -560 M180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L4 SYMATTR Value 470µ 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 0.047µ TEXT -632 472 Left 2 !.tran 5m startup uic TEXT -712 -360 Left 2 !K L1 L2 L3 L4 0.99

On a sunny day (Tue, 21 Sep 2021 02:55:18 -0400) it happened bitrex snipped-for-privacy@example.net wrote in <rlf2J.13646$ snipped-for-privacy@fx21.iad:

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

from this: 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.

you can see the small current transformer at the bottom in red wire from the drain of the MOSFET. 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 those Chinese induction things: later...

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.

<snip>

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

Here is a sine oscillator.

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.

kw

My 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!

On 9/21/2021 1:31 PM, John Larkin wrote:

It works OK to put out ~150 volts thru a small toroid transformer you could wind by hand, into a bridge doubler. I use 4.7uH for the primary,

220u for the secondary, 1u for the feedback, 0.47u for the tank cap, 680 ohms and 2.2u for the AGC RC.

Probably any 30 volt 3 amp NPN would work OK

The frequency of oscillation is about 100kHz and efficiency looks to be

70-something percent, I don't think you could hope for much more from this topology in a high step-up ratio arrangement, as the base transistor burns a fair amount of power to give the Q sufficient drive.

I don't think Schottky diodes are really needed here but we got 'em.

(make sure "alternate solver" is turned on, the normal solver hates these type of circuits)

Version 4 SHEET 1 1148 680 WIRE -416 -752 -496 -752 WIRE 112 -752 -416 -752 WIRE -416 -624 -416 -752 WIRE -48 -624 -416 -624 WIRE 480 -624 320 -624 WIRE 784 -624 544 -624 WIRE 912 -624 784 -624 WIRE 1056 -624 912 -624 WIRE -672 -576 -672 -624 WIRE 400 -528 224 -528 WIRE 480 -528 400 -528 WIRE 784 -528 784 -624 WIRE 784 -528 544 -528 WIRE 224 -480 224 -528 WIRE 784 -464 784 -528 WIRE -672 -448 -672 -496 WIRE 912 -400 912 -624 WIRE 1056 -368 1056 -624 WIRE -48 -352 -48 -624 WIRE 112 -336 112 -752 WIRE 224 -336 224 -400 WIRE 320 -336 320 -624 WIRE 320 -336 224 -336 WIRE 784 -336 784 -400 WIRE 784 -336 320 -336 WIRE 784 -272 784 -336 WIRE 400 -208 400 -528 WIRE 480 -208 400 -208 WIRE 608 -208 544 -208 WIRE -416 -176 -416 -624 WIRE 320 -112 320 -336 WIRE 480 -112 320 -112 WIRE 608 -112 608 -208 WIRE 608 -112 544 -112 WIRE 784 -112 784 -208 WIRE 784 -112 608 -112 WIRE 912 -112 912 -336 WIRE 912 -112 784 -112 WIRE 1056 -112 1056 -288 WIRE 1056 -112 912 -112 WIRE -48 -96 -48 -272 WIRE -48 -96 -288 -96 WIRE 112 -96 112 -272 WIRE 112 -96 -48 -96 WIRE 784 -80 784 -112 WIRE 784 -64 784 -80 WIRE -288 0 -288 -96 WIRE 784 32 784 0 WIRE -416 48 -416 -96 WIRE -352 48 -416 48 WIRE -416 160 -416 48 WIRE -288 160 -288 96 WIRE -416 288 -416 224 WIRE -288 288 -288 240 FLAG -496 -752 +5 IOPIN -496 -752 In FLAG -288 288 0 FLAG -672 -448 0 FLAG -672 -624 +5 IOPIN -672 -624 Out FLAG 784 32 0 FLAG -416 288 0 SYMBOL ind2 -32 -368 M0 WINDOW 3 -49 82 Left 2 SYMATTR InstName L1 SYMATTR Value 4.7µ SYMBOL ind2 240 -496 M0 SYMATTR InstName L2 SYMATTR Value 220µ SYMBOL ind2 -304 256 M180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L3 SYMATTR Value 1µ SYMBOL npn -352 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 0.47µ SYMBOL res -400 -80 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R3 SYMATTR Value 680 SYMBOL cap -400 224 R180 WINDOW 0 24 56 Left 2 WINDOW 3 24 8 Left 2 SYMATTR InstName C2 SYMATTR Value 2.2µ SYMBOL voltage -672 -592 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL cap 768 -272 R0 SYMATTR InstName C3 SYMATTR Value 0.1µ SYMBOL res 768 -96 R0 SYMATTR InstName R1 SYMATTR Value 1Meg SYMBOL current 1056 -368 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName I1 SYMATTR Value 0.005 SYMBOL cap 768 -464 R0 SYMATTR InstName C4 SYMATTR Value 0.1µ SYMBOL cap 896 -400 R0 SYMATTR InstName C5 SYMATTR Value 0.47µ SYMBOL schottky 544 -128 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName D4 SYMATTR Value RB168L150 SYMATTR Description Diode SYMATTR Type diode SYMBOL schottky 544 -224 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName D1 SYMATTR Value RB168L150 SYMATTR Description Diode SYMATTR Type diode SYMBOL schottky 480 -608 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D2 SYMATTR Value RB168L150 SYMATTR Description Diode SYMATTR Type diode SYMBOL schottky 480 -512 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D3 SYMATTR Value RB168L150 SYMATTR Description Diode SYMATTR Type diode TEXT -816 -328 Left 2 !.tran 10m startup uic TEXT -792 -360 Left 2 !K L1 L2 L3 0.99

Base resistor, rather

If you have a design with a transformer that can be wound on a small toroid in a couple minutes, and you have a girlfriend that enjoys knitting, then you have new employee