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A less squirrely cute little circuit

This is an LTSpice model of Tim William's circuit, changed more or less as John Larkin suggested. It costs a few extra components to keep it stable and stop it feeding current spikes back into the 9V supply, but fewer than are needed to keep Tim's original circuit tidy - see my recent postings to that thread.

The ferrite beads L9 and L10 stop the high voltage output rectifier from messing up the inverter, and let it run at 135kHz.

Version 4 SHEET 1 1296 836 WIRE -1184 -720 -1232 -720 WIRE -880 -720 -1120 -720 WIRE -304 -720 -880 -720 WIRE -48 -720 -304 -720 WIRE 112 -720 -48 -720 WIRE -880 -688 -880 -720 WIRE 112 -688 112 -720 WIRE -304 -672 -304 -720 WIRE -304 -432 -304 -592 WIRE -48 -432 -48 -720 WIRE -880 -384 -880 -608 WIRE -368 -384 -880 -384 WIRE 896 -272 864 -272 WIRE 976 -272 960 -272 WIRE 1072 -272 976 -272 WIRE 1200 -272 1072 -272 WIRE -304 -256 -304 -336 WIRE -304 -256 -448 -256 WIRE -208 -256 -304 -256 WIRE 16 -256 -128 -256 WIRE 176 -256 16 -256 WIRE 368 -256 176 -256 WIRE 16 -224 16 -256 WIRE 176 -208 176 -256 WIRE 368 -208 368 -256 WIRE 864 -192 864 -272 WIRE 1200 -176 1200 -272 WIRE 976 -144 976 -272 WIRE 16 -128 16 -160 WIRE 112 -128 112 -624 WIRE 112 -128 16 -128 WIRE 176 -128 176 -144 WIRE 176 -128 112 -128 WIRE 368 -112 368 -144 WIRE 176 -96 176 -128 WIRE -448 -80 -448 -256 WIRE 864 -80 864 -128 WIRE 224 16 64 16 WIRE 448 16 224 16 WIRE 784 16 624 16 WIRE 864 16 864 -16 WIRE 864 16 784 16 WIRE 448 32 448 16 WIRE 64 48 64 16 WIRE 624 80 624 16 WIRE 784 80 784 16 WIRE -448 96 -448 0 WIRE 0 96 -160 96 WIRE 224 112 224 16 WIRE -160 128 -160 96 WIRE -1232 144 -1232 -720 WIRE 368 144 368 -32 WIRE 448 144 448 112 WIRE 448 144 368 144 WIRE 1072 144 1072 -272 WIRE 448 176 448 144 WIRE -160 240 -160 208 WIRE -48 240 -48 -352 WIRE -48 240 -160 240 WIRE -160 272 -160 240 WIRE 624 272 624 160 WIRE 784 272 784 144 WIRE 784 272 624 272 WIRE 976 272 976 -80 WIRE 976 272 784 272 WIRE 992 272 976 272 WIRE 224 288 224 176 WIRE 448 288 448 256 WIRE 448 288 224 288 WIRE 864 288 864 16 WIRE 224 320 224 288 WIRE 992 352 992 272 WIRE -160 368 -160 352 WIRE 160 368 -160 368 WIRE 864 384 864 352 WIRE 1200 400 1200 -96 WIRE 64 448 64 144 WIRE 224 448 224 416 WIRE 224 448 64 448 WIRE -880 496 -880 -384 WIRE -832 496 -880 496 WIRE -448 496 -448 160 WIRE -448 496 -576 496 WIRE -352 496 -448 496 WIRE -208 496 -352 496 WIRE 1200 496 1200 480 WIRE 1200 496 -144 496 WIRE 1200 528 1200 496 WIRE 864 560 864 448 WIRE -352 576 -352 496 WIRE -880 624 -880 496 WIRE -832 624 -880 624 WIRE -544 624 -576 624 WIRE -48 624 -48 240 WIRE 1200 640 1200 608 WIRE -544 688 -544 624 WIRE -544 688 -576 688 WIRE -1232 768 -1232 224 WIRE -544 768 -544 688 WIRE -544 768 -1232 768 WIRE -352 768 -352 640 WIRE -352 768 -544 768 WIRE -48 768 -48 704 WIRE -48 768 -352 768 WIRE 224 768 224 448 WIRE 224 768 -48 768 WIRE 784 768 224 768 WIRE 864 768 864 624 WIRE 864 768 784 768 WIRE 992 768 992 416 WIRE 992 768 864 768 WIRE 1072 768 1072 208 WIRE 1072 768 992 768 WIRE 1200 768 1200 720 WIRE 1200 768 1072 768 WIRE 784 816 784 768 FLAG 784 816 0 FLAG 176 -96 0 SYMBOL npn 160 320 R0 SYMATTR InstName Q1 SYMATTR Value 2N4401 SYMBOL npn 0 48 R0 SYMATTR InstName Q2 SYMATTR Value 2N4401 SYMBOL ind2 432 16 R0 SYMATTR InstName L1 SYMATTR Value 44µ SYMATTR Type ind SYMATTR SpiceLine Rser=0.1 Cpar=1p SYMBOL ind2 432 160 R0 SYMATTR InstName L2 SYMATTR Value 44µ SYMATTR Type ind SYMATTR SpiceLine Rser=0.1 Cpar=1p SYMBOL cap 208 112 R0 SYMATTR InstName C1 SYMATTR Value 2.2n SYMBOL ind2 608 64 R0 SYMATTR InstName L5 SYMATTR Value 4.4m SYMATTR Type ind SYMATTR SpiceLine Rser=0.1 Cpar=1p SYMBOL cap 768 80 R0 SYMATTR InstName C2 SYMATTR Value 220p SYMBOL diode 880 -16 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D1 SYMATTR Value 1N914 SYMBOL diode 880 -128 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D2 SYMATTR Value 1N914 SYMBOL diode 880 352 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D3 SYMATTR Value 1N914 SYMBOL diode 880 448 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D4 SYMATTR Value 1N914 SYMBOL cap 960 -144 R0 SYMATTR InstName C3 SYMATTR Value 6.8n SYMBOL cap 976 352 R0 SYMATTR InstName C4 SYMATTR Value 6.8n SYMBOL cap 1056 144 R0 SYMATTR InstName C5 SYMATTR Value 100n SYMBOL res 1184 -192 R0 SYMATTR InstName R1 SYMATTR Value 1000k SYMBOL res 1184 384 R0 SYMATTR InstName P1a SYMATTR Value 5k SYMBOL res 1184 512 R0 SYMATTR InstName P1b SYMATTR Value 5k SYMBOL res 1184 624 R0 SYMATTR InstName R4 SYMATTR Value 15k SYMBOL ind2 -144 224 R180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L3 SYMATTR Value 4µ SYMATTR Type ind SYMATTR SpiceLine Rser=0.1 Cpar=1p SYMBOL ind2 -144 368 R180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L4 SYMATTR Value 4µ SYMATTR Type ind SYMATTR SpiceLine Rser=0.1 Cpar=1p SYMBOL ind 352 -128 R0 SYMATTR InstName L6 SYMATTR Value 270µ SYMATTR SpiceLine Rser=1 Cpar=1p SYMBOL polcap 160 -208 R0 WINDOW 3 24 56 Left 2 SYMATTR Value 47µ SYMATTR InstName C6 SYMATTR Description Capacitor SYMATTR Type cap SYMATTR SpiceLine V=4 Irms=0 Rser=2.4 Lser=0 mfg="AVX" pn="TAJB476M004" type="Tantalum" SYMBOL References\\LT1431 -704 592 R0 SYMATTR InstName U1 SYMBOL res -64 -448 R0 SYMATTR InstName R2 SYMATTR Value 6.8k SYMBOL res -64 608 R0 SYMATTR InstName R3 SYMATTR Value 680 SYMBOL voltage -1232 128 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 9 SYMBOL FerriteBead -1152 -720 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L7 SYMATTR Value 3.642µ SYMATTR SpiceLine Ipk=0.2 Rser=0.6 Rpar=2700 Cpar=1.122p mfg="Wurth Elektronik" pn="742 792 092" SYMBOL FerriteBead 368 -176 R180 SYMATTR InstName L8 SYMATTR Value 3.642µ SYMATTR SpiceLine Ipk=0.2 Rser=0.6 Rpar=2700 Cpar=1.122p mfg="Wurth Elektronik" pn="742 792 092" SYMBOL npn -368 -432 R0 SYMATTR InstName Q3 SYMATTR Value 2N4401 SYMBOL FerriteBead 928 -272 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L9 SYMATTR Value 3.642µ SYMATTR SpiceLine Ipk=0.2 Rser=0.6 Rpar=2700 Cpar=1.122p mfg="Wurth Elektronik" pn="742 792 092" SYMBOL FerriteBead 864 592 R180 SYMATTR InstName L10 SYMATTR Value 3.642µ SYMATTR SpiceLine Ipk=0.2 Rser=0.6 Rpar=2700 Cpar=1.122p mfg="Wurth Elektronik" pn="742 792 092" SYMBOL res -464 -96 R0 SYMATTR InstName R7 SYMATTR Value 47k SYMBOL cap -464 96 R0 SYMATTR InstName C7 SYMATTR Value 10n SYMBOL res -896 -704 R0 SYMATTR InstName R5 SYMATTR Value 1k SYMBOL res -320 -688 R0 SYMATTR InstName R6 SYMATTR Value 100 SYMBOL FerriteBead -176 496 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L11 SYMATTR Value 3.642µ SYMATTR SpiceLine Ipk=0.2 Rser=0.6 Rpar=2700 Cpar=1.122p mfg="Wurth Elektronik" pn="742 792 092" SYMBOL cap -368 576 R0 SYMATTR InstName C8 SYMATTR Value 22n SYMBOL cap 0 -224 R0 SYMATTR InstName C9 SYMATTR Value 100n SYMBOL cap 96 -688 R0 SYMATTR InstName C10 SYMATTR Value 100n SYMBOL ind -112 -272 R90 WINDOW 0 5 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName L13 SYMATTR Value 4.7m SYMATTR SpiceLine Rser=13.8 Cpar=5p TEXT 368 352 Left 2 !K1 L1 L2 L3 L4 L5 0.999 TEXT 552 104 Left 2 ;| TEXT 552 128 Left 2 ;| TEXT 536 104 Left 2 ;| TEXT 536 128 Left 2 ;| TEXT -728 816 Left 2 !.tran 0 50m 0 10n startup TEXT -208 -192 Left 2 ;Multicomp TEXT -232 -160 Left 2 ;MCSD75_472KU TEXT -224 -128 Left 2 ;Farnell 1864155

--
Bill Sloman, Nijmegen
Reply to
Bill Sloman
Loading thread data ...

Got a screen shot?

Tim

-- Deep Friar: a very philosophical monk. Website:

formatting link

Reply to
Tim Williams

Just remember - it IS a power supply. Sometimes a simulation likes a load, too.

RL

Reply to
legg

Tim can tell us what it is.

-- Bill Sloman, Nijmegen

Reply to
Bill Sloman

I don't use LTSpice, I have Multisim here. Screenshot?

Tim

-- Deep Friar: a very philosophical monk. Website:

formatting link

Tim can tell us what it is.

-- Bill Sloman, Nijmegen

Reply to
Tim Williams

Send me your e-mail address ( snipped-for-privacy@ieee.org is real and works) and and I'll send you the cut and pasted schematic.

In principle I could put it on my web site, but it seems a bit excessive when you can just paste the text file I posted into NotePad, correct the extension from .txt to .asc and look at it (or run it) with LTSpice.

-- Bill Sloman, Nijmegen

Reply to
Bill Sloman

You computer should have room for both - LTSpice is free and doesn't take long to download. It has been used here before as medium for exchanging schematics.

LTSpice can also generate a Spice file (as well as the schematic) which Multisim should be able to run. Just send me you e-mail address and I'll send you that as well.

-- Bill Sloman, Nijmegen

Reply to
Bill Sloman

My e-mail is present in my headers. Perhaps tedious to coax out of Google Groups, but it's there (as well as from any other newsreader and server). Otherwise just post it on Imgur.com.

Tim

-- Deep Friar: a very philosophical monk. Website:

formatting link

Send me your e-mail address ( snipped-for-privacy@ieee.org is real and works) and and I'll send you the cut and pasted schematic.

In principle I could put it on my web site, but it seems a bit excessive when you can just paste the text file I posted into NotePad, correct the extension from .txt to .asc and look at it (or run it) with LTSpice.

-- Bill Sloman, Nijmegen

Reply to
Tim Williams

Oddly enough, Multisim supports importing schematics as netlists -- it takes a good minute or so to synthesize the schematic with symbols, and makes an ungodly mess anyway, but that it does it at all is actually pretty impressive. I don't care much for spice without a circuit since I'll see at a glance what's different.

Tim

-- Deep Friar: a very philosophical monk. Website:

formatting link

You computer should have room for both - LTSpice is free and doesn't take long to download. It has been used here before as medium for exchanging schematics.

LTSpice can also generate a Spice file (as well as the schematic) which Multisim should be able to run. Just send me you e-mail address and I'll send you that as well.

-- Bill Sloman, Nijmegen

Reply to
Tim Williams

formatting link

Reply to
bitrex

Thanks!

That 4.7m is an awful lot for a half watt converter. Not that it's much bigger given the current consumption,

Inductance is a bit low, FT50-43 with 15 turns should be more like 110uH. Not going to make a big difference, and it'll vary with signal level anyway.

C8 looks like a *bad* idea..

Why not ditch L13, L6, C6 and C9, and switch Q3 to a transconductance stage? Heck, with R5 and R6 where they are, just change to PNP and add a series resistor from base to '431; move compensation back to '431 cathode. Distortion will probably be lower as it isn't limited by L6's finite inductance.

Any particular reason for R2-R3? I've found they don't really matter, as long as they're low enough to put Q1-Q2 in the linear range when starting up, and keep them saturated while oscillating. Values R2 = 1k to 10k and R3 = infty appear to work.

Tempted to make an AC Baker clamp, so the bias current at R2 is proportional to AC voltage. At low voltage, just a trickle is supplied, limiting dissipation; as amplitude builds (peak detector + amplifier?), bias is cranked up to a maximum value (about equivalent to a 1k resistor). Hmm, if this subcircuit had a considerable time dependancy, it could do *very* interesting things against the outer loop (being negative impedance). Two solutions: leave it; or, make it so the current is proportional to voltage, in which case, it does *exactly* what the BJTs want -- proportional bias.

Don't worry, I still have a year to patent ;-)

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
Reply to
Tim Williams

From the original schematic - 3mA.

RL

RL

Reply to
legg

s much

That was my feeling too, but anything much less and the current through Q3 drops back to zero every cycle. The part I've used costs about $0.20 in small quantities.

You gave 10T+10T+100T on your circuit diagram.

ay.

If you connect R7 to the other side of L13, you don't need either C8 or L11. I should have seen that - thanks. That change significantly reduces the time the circuit takes to start up, as you'd expect. There's 8mV of 275kHz ripple in the REF input to the LT1431, but that doesn't mess up the long-tailed pair comparing the input with the internal reference too badly - the REF input sits at 2.5000785V

+/-4.15mV rather than 2.500V but the extra 78.5uV isn't going to worry anybody.

ge?

Post a circuit digram. I suspect that you are ignoring collector-base feedback - which was what made your original circuit so hard to tame - but I'm not going to think about it until I know exactly what you've got in mind

as

and R3

I often skipped R3, and drawn all the base drive from the supply rail. Putting in R3 allows you to increase R2 - making the circuit more efficient, because then more of the base current is supplied through R3 and L3/L4 - the base-drive winding - at a 5:1 step-down from the supply rail.

nal

, if

Two

e,

Anything that can do, MOSFET switches can do better.

-- Bill Sloman, Nijmegen

Reply to
Bill Sloman

On Aug 2, 5:16 am, legg wrote:

ss

t

rom

Sorry. I should have noticed.

Tim - correctly - objected to C8 and L11, and if you hook up R7 to the other side of L13, you don't need them. R6 has to be reduced to cope with a 3mA load on the output, and the 2N4401 will probably run out of current gain before R6 starts doing anything useful.

D5 protects the base-emitter junction of Q3, which wouldn't last long without it. I've been meaning to put that in for some time now, and have finally got around to it.

Here's the revised circuit diagram. Tim wants to try a slightly different circuit - precisely how different isn't immediately clear to me - but if he posts a circuit diagram we can take it from there.

Version 4 SHEET 1 1412 836 WIRE -1184 -720 -1232 -720 WIRE -880 -720 -1120 -720 WIRE -304 -720 -880 -720 WIRE -48 -720 -304 -720 WIRE 112 -720 -48 -720 WIRE -880 -688 -880 -720 WIRE 112 -688 112 -720 WIRE -304 -672 -304 -720 WIRE -304 -432 -304 -592 WIRE -48 -432 -48 -720 WIRE -880 -384 -880 -608 WIRE -624 -384 -880 -384 WIRE -368 -384 -624 -384 WIRE -624 -368 -624 -384 WIRE 368 -304 -448 -304 WIRE 896 -272 864 -272 WIRE 976 -272 960 -272 WIRE 1072 -272 976 -272 WIRE 1200 -272 1072 -272 WIRE 1344 -272 1200 -272 WIRE -624 -256 -624 -304 WIRE -304 -256 -304 -336 WIRE -304 -256 -624 -256 WIRE -208 -256 -304 -256 WIRE 16 -256 -128 -256 WIRE 176 -256 16 -256 WIRE 368 -256 368 -304 WIRE 368 -256 176 -256 WIRE 16 -224 16 -256 WIRE 176 -208 176 -256 WIRE 368 -208 368 -256 WIRE 864 -192 864 -272 WIRE 1200 -176 1200 -272 WIRE 976 -144 976 -272 WIRE 16 -128 16 -160 WIRE 112 -128 112 -624 WIRE 112 -128 16 -128 WIRE 176 -128 176 -144 WIRE 176 -128 112 -128 WIRE 368 -112 368 -144 WIRE 176 -96 176 -128 WIRE -448 -80 -448 -304 WIRE 864 -80 864 -128 WIRE 224 16 64 16 WIRE 448 16 224 16 WIRE 784 16 624 16 WIRE 864 16 864 -16 WIRE 864 16 784 16 WIRE 448 32 448 16 WIRE 64 48 64 16 WIRE 624 80 624 16 WIRE 784 80 784 16 WIRE -448 96 -448 0 WIRE 0 96 -160 96 WIRE 224 112 224 16 WIRE -160 128 -160 96 WIRE -1232 144 -1232 -720 WIRE 368 144 368 -32 WIRE 448 144 448 112 WIRE 448 144 368 144 WIRE 1072 144 1072 -272 WIRE 1344 144 1344 -272 WIRE 448 176 448 144 WIRE -160 240 -160 208 WIRE -48 240 -48 -352 WIRE -48 240 -160 240 WIRE -160 272 -160 240 WIRE 624 272 624 160 WIRE 784 272 784 144 WIRE 784 272 624 272 WIRE 976 272 976 -80 WIRE 976 272 784 272 WIRE 992 272 976 272 WIRE 224 288 224 176 WIRE 448 288 448 256 WIRE 448 288 224 288 WIRE 864 288 864 16 WIRE 224 320 224 288 WIRE 992 352 992 272 WIRE -160 368 -160 352 WIRE 160 368 -160 368 WIRE 864 384 864 352 WIRE 1200 400 1200 -96 WIRE 64 448 64 144 WIRE 224 448 224 416 WIRE 224 448 64 448 WIRE -880 496 -880 -384 WIRE -832 496 -880 496 WIRE -448 496 -448 160 WIRE -448 496 -576 496 WIRE 1200 496 1200 480 WIRE 1200 496 -448 496 WIRE 1200 528 1200 496 WIRE 864 560 864 448 WIRE -880 624 -880 496 WIRE -832 624 -880 624 WIRE -544 624 -576 624 WIRE -48 624 -48 240 WIRE 1200 640 1200 608 WIRE -544 688 -544 624 WIRE -544 688 -576 688 WIRE -1232 768 -1232 224 WIRE -544 768 -544 688 WIRE -544 768 -1232 768 WIRE -48 768 -48 704 WIRE -48 768 -544 768 WIRE 224 768 224 448 WIRE 224 768 -48 768 WIRE 784 768 224 768 WIRE 864 768 864 624 WIRE 864 768 784 768 WIRE 992 768 992 416 WIRE 992 768 864 768 WIRE 1072 768 1072 208 WIRE 1072 768 992 768 WIRE 1200 768 1200 720 WIRE 1200 768 1072 768 WIRE 1344 768 1344 224 WIRE 1344 768 1200 768 WIRE 784 816 784 768 FLAG 784 816 0 FLAG 176 -96 0 SYMBOL npn 160 320 R0 SYMATTR InstName Q1 SYMATTR Value 2N4401 SYMBOL npn 0 48 R0 SYMATTR InstName Q2 SYMATTR Value 2N4401 SYMBOL ind2 432 16 R0 SYMATTR InstName L1 SYMATTR Value 44=B5 SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL ind2 432 160 R0 SYMATTR InstName L2 SYMATTR Value 44=B5 SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL cap 208 112 R0 SYMATTR InstName C1 SYMATTR Value 2.2n SYMBOL ind2 608 64 R0 SYMATTR InstName L5 SYMATTR Value 4.4m SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL cap 768 80 R0 SYMATTR InstName C2 SYMATTR Value 220p SYMBOL diode 880 -16 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D1 SYMATTR Value 1N914 SYMBOL diode 880 -128 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D2 SYMATTR Value 1N914 SYMBOL diode 880 352 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D3 SYMATTR Value 1N914 SYMBOL diode 880 448 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D4 SYMATTR Value 1N914 SYMBOL cap 960 -144 R0 SYMATTR InstName C3 SYMATTR Value 6.8n SYMBOL cap 976 352 R0 SYMATTR InstName C4 SYMATTR Value 6.8n SYMBOL cap 1056 144 R0 SYMATTR InstName C5 SYMATTR Value 100n SYMBOL res 1184 -192 R0 SYMATTR InstName R1 SYMATTR Value 1000k SYMBOL res 1184 384 R0 SYMATTR InstName P1a SYMATTR Value 5k SYMBOL res 1184 512 R0 SYMATTR InstName P1b SYMATTR Value 5k SYMBOL res 1184 624 R0 SYMATTR InstName R4 SYMATTR Value 15k SYMBOL ind2 -144 224 R180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L3 SYMATTR Value 4=B5 SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL ind2 -144 368 R180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L4 SYMATTR Value 4=B5 SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL ind 352 -128 R0 SYMATTR InstName L6 SYMATTR Value 270=B5 SYMATTR SpiceLine Rser=3D1 Cpar=3D1p SYMBOL polcap 160 -208 R0 WINDOW 3 24 56 Left 2 SYMATTR Value 47=B5 SYMATTR InstName C6 SYMATTR Description Capacitor SYMATTR Type cap SYMATTR SpiceLine V=3D4 Irms=3D0 Rser=3D2.4 Lser=3D0 mfg=3D"AVX" pn=3D"TAJB476M004" type=3D"Tantalum" SYMBOL References\\LT1431 -704 592 R0 SYMATTR InstName U1 SYMBOL res -64 -448 R0 SYMATTR InstName R2 SYMATTR Value 6.8k SYMBOL res -64 608 R0 SYMATTR InstName R3 SYMATTR Value 680 SYMBOL voltage -1232 128 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 9 SYMBOL FerriteBead -1152 -720 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L7 SYMATTR Value 3.642=B5 SYMATTR SpiceLine Ipk=3D0.2 Rser=3D0.6 Rpar=3D2700 Cpar=3D1.122p mfg=3D"Wur= th Elektronik" pn=3D"742 792 092" SYMBOL FerriteBead 368 -176 R180 SYMATTR InstName L8 SYMATTR Value 3.642=B5 SYMATTR SpiceLine Ipk=3D0.2 Rser=3D0.6 Rpar=3D2700 Cpar=3D1.122p mfg=3D"Wur= th Elektronik" pn=3D"742 792 092" SYMBOL npn -368 -432 R0 SYMATTR InstName Q3 SYMATTR Value 2N4401 SYMBOL FerriteBead 928 -272 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L9 SYMATTR Value 3.642=B5 SYMATTR SpiceLine Ipk=3D0.2 Rser=3D0.6 Rpar=3D2700 Cpar=3D1.122p mfg=3D"Wur= th Elektronik" pn=3D"742 792 092" SYMBOL FerriteBead 864 592 R180 SYMATTR InstName L10 SYMATTR Value 3.642=B5 SYMATTR SpiceLine Ipk=3D0.2 Rser=3D0.6 Rpar=3D2700 Cpar=3D1.122p mfg=3D"Wur= th Elektronik" pn=3D"742 792 092" SYMBOL res -464 -96 R0 SYMATTR InstName R7 SYMATTR Value 47k SYMBOL cap -464 96 R0 SYMATTR InstName C7 SYMATTR Value 10n SYMBOL res -896 -704 R0 SYMATTR InstName R5 SYMATTR Value 1k SYMBOL res -320 -688 R0 SYMATTR InstName R6 SYMATTR Value 10 SYMBOL cap 0 -224 R0 SYMATTR InstName C9 SYMATTR Value 100n SYMBOL cap 96 -688 R0 SYMATTR InstName C10 SYMATTR Value 100n SYMBOL ind -112 -272 R90 WINDOW 0 5 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName L13 SYMATTR Value 4.7m SYMATTR SpiceLine Rser=3D13.8 Cpar=3D5p SYMBOL res 1328 128 R0 SYMATTR InstName R8 SYMATTR Value 43k SYMBOL diode -608 -304 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D5 SYMATTR Value 1N914 TEXT 368 352 Left 2 !K1 L1 L2 L3 L4 L5 0.999 TEXT 552 104 Left 2 ;| TEXT 552 128 Left 2 ;| TEXT 536 104 Left 2 ;| TEXT 536 128 Left 2 ;| TEXT -728 816 Left 2 !.tran 0 50m 0 10n startup TEXT -208 -192 Left 2 ;Multicomp TEXT -232 -160 Left 2 ;MCSD75_472KU TEXT -224 -128 Left 2 ;Farnell 1864155

-- Bill Sloman, Nijmegen

Reply to
Bill Sloman

Have either of you have looked at the basic circuit closely enough to be making any changes?

Going back to basics:

formatting link

RL

Reply to
legg

Tell us what's worrying you in plain text - I don't feel like ploughing through through the collection of files you've stuff into your zipped collection to find out what you are actually on about.

-- Bill Sloman, Nijmegen

Reply to
Bill Sloman

Read the text file. It's the only one so I didn't think the title 'readme.1st' was justified.

There are some jpg images there, which should show a relationship between input and output, over the control range. The files and images are associated by file name.

The relative slopes of current drain will give info on charging penalties before the load is actually engaged on the output.

The point at which the error amplifier output switches indicates supply and reg node requirements, at the load presented, regarless of the control method used.

Note that abnormally hf operation is not present in the first iteration of the original schematic - this is (apparently) actually an artifact of the feedback network..........

You are welcome.

RL

Reply to
legg

On Aug 3, 12:14=A0am, legg wrote:

o

I can't say that I'm much wiser after reading the text file. It's all a bit unspecific

I've had another go at the circuit

Version 4 SHEET 1 1412 836 WIRE -1184 -720 -1232 -720 WIRE -880 -720 -1120 -720 WIRE -304 -720 -880 -720 WIRE -48 -720 -304 -720 WIRE 112 -720 -48 -720 WIRE -880 -688 -880 -720 WIRE 112 -688 112 -720 WIRE -304 -672 -304 -720 WIRE -304 -432 -304 -592 WIRE -48 -432 -48 -720 WIRE -880 -384 -880 -608 WIRE -624 -384 -880 -384 WIRE -368 -384 -624 -384 WIRE -624 -368 -624 -384 WIRE 896 -272 864 -272 WIRE 976 -272 960 -272 WIRE 1072 -272 976 -272 WIRE 1200 -272 1072 -272 WIRE 1344 -272 1200 -272 WIRE -624 -256 -624 -304 WIRE -448 -256 -624 -256 WIRE -304 -256 -304 -336 WIRE -304 -256 -448 -256 WIRE -208 -256 -304 -256 WIRE 16 -256 -128 -256 WIRE 176 -256 16 -256 WIRE 368 -256 176 -256 WIRE 16 -224 16 -256 WIRE 176 -208 176 -256 WIRE 368 -208 368 -256 WIRE 864 -192 864 -272 WIRE 1200 -176 1200 -272 WIRE 976 -144 976 -272 WIRE 16 -128 16 -160 WIRE 112 -128 112 -624 WIRE 112 -128 16 -128 WIRE 176 -128 176 -144 WIRE 176 -128 112 -128 WIRE 368 -112 368 -144 WIRE -880 -96 -880 -384 WIRE -880 -96 -1024 -96 WIRE 176 -96 176 -128 WIRE -448 -80 -448 -256 WIRE 864 -80 864 -128 WIRE 224 16 64 16 WIRE 448 16 224 16 WIRE 784 16 624 16 WIRE 864 16 864 -16 WIRE 864 16 784 16 WIRE 448 32 448 16 WIRE 64 48 64 16 WIRE 624 80 624 16 WIRE 784 80 784 16 WIRE -448 96 -448 0 WIRE 0 96 -160 96 WIRE 224 112 224 16 WIRE -160 128 -160 96 WIRE -1232 144 -1232 -720 WIRE 368 144 368 -32 WIRE 448 144 448 112 WIRE 448 144 368 144 WIRE 1072 144 1072 -272 WIRE 1344 144 1344 -272 WIRE 448 176 448 144 WIRE -160 240 -160 208 WIRE -48 240 -48 -352 WIRE -48 240 -160 240 WIRE -1024 272 -1024 -96 WIRE -160 272 -160 240 WIRE 624 272 624 160 WIRE 784 272 784 144 WIRE 784 272 624 272 WIRE 976 272 976 -80 WIRE 976 272 784 272 WIRE 992 272 976 272 WIRE 224 288 224 176 WIRE 448 288 448 256 WIRE 448 288 224 288 WIRE 864 288 864 16 WIRE 224 320 224 288 WIRE 992 352 992 272 WIRE -160 368 -160 352 WIRE 160 368 -160 368 WIRE 864 384 864 352 WIRE 1200 384 1200 -96 WIRE 64 448 64 144 WIRE 224 448 224 416 WIRE 224 448 64 448 WIRE -880 496 -880 -96 WIRE -832 496 -880 496 WIRE -448 496 -448 160 WIRE -448 496 -576 496 WIRE 1200 496 1200 464 WIRE 1200 496 -448 496 WIRE 1200 528 1200 496 WIRE 864 560 864 448 WIRE -880 624 -880 496 WIRE -832 624 -880 624 WIRE -544 624 -576 624 WIRE -48 624 -48 240 WIRE 1200 640 1200 608 WIRE -544 688 -544 624 WIRE -544 688 -576 688 WIRE -1232 768 -1232 224 WIRE -1024 768 -1024 336 WIRE -1024 768 -1232 768 WIRE -544 768 -544 688 WIRE -544 768 -1024 768 WIRE -48 768 -48 704 WIRE -48 768 -544 768 WIRE 224 768 224 448 WIRE 224 768 -48 768 WIRE 784 768 224 768 WIRE 864 768 864 624 WIRE 864 768 784 768 WIRE 992 768 992 416 WIRE 992 768 864 768 WIRE 1072 768 1072 208 WIRE 1072 768 992 768 WIRE 1200 768 1200 720 WIRE 1200 768 1072 768 WIRE 1344 768 1344 224 WIRE 1344 768 1200 768 WIRE 784 816 784 768 FLAG 784 816 0 FLAG 176 -96 0 SYMBOL npn 160 320 R0 SYMATTR InstName Q1 SYMATTR Value 2N4401 SYMBOL npn 0 48 R0 SYMATTR InstName Q2 SYMATTR Value 2N4401 SYMBOL ind2 432 16 R0 SYMATTR InstName L1 SYMATTR Value 44=B5 SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL ind2 432 160 R0 SYMATTR InstName L2 SYMATTR Value 44=B5 SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL cap 208 112 R0 SYMATTR InstName C1 SYMATTR Value 2.2n SYMBOL ind2 608 64 R0 SYMATTR InstName L5 SYMATTR Value 4.4m SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL cap 768 80 R0 SYMATTR InstName C2 SYMATTR Value 220p SYMBOL diode 880 -16 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D1 SYMATTR Value 1N914 SYMBOL diode 880 -128 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D2 SYMATTR Value 1N914 SYMBOL diode 880 352 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D3 SYMATTR Value 1N914 SYMBOL diode 880 448 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D4 SYMATTR Value 1N914 SYMBOL cap 960 -144 R0 SYMATTR InstName C3 SYMATTR Value 6.8n SYMBOL cap 976 352 R0 SYMATTR InstName C4 SYMATTR Value 6.8n SYMBOL cap 1056 144 R0 SYMATTR InstName C5 SYMATTR Value 100n SYMBOL res 1184 -192 R0 SYMATTR InstName R1 SYMATTR Value 1000k SYMBOL res 1184 368 R0 SYMATTR InstName P1a SYMATTR Value 5k SYMBOL res 1184 512 R0 SYMATTR InstName P1b SYMATTR Value 5k SYMBOL res 1184 624 R0 SYMATTR InstName R4 SYMATTR Value 15k SYMBOL ind2 -144 224 R180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L3 SYMATTR Value 4=B5 SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL ind2 -144 368 R180 WINDOW 0 36 80 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName L4 SYMATTR Value 4=B5 SYMATTR Type ind SYMATTR SpiceLine Rser=3D0.1 Cpar=3D1p SYMBOL ind 352 -128 R0 SYMATTR InstName L6 SYMATTR Value 270=B5 SYMATTR SpiceLine Rser=3D1 Cpar=3D1p SYMBOL polcap 160 -208 R0 WINDOW 3 24 56 Left 2 SYMATTR Value 47=B5 SYMATTR InstName C6 SYMATTR Description Capacitor SYMATTR Type cap SYMATTR SpiceLine V=3D4 Irms=3D0 Rser=3D2.4 Lser=3D0 mfg=3D"AVX" pn=3D"TAJB476M004" type=3D"Tantalum" SYMBOL References\\LT1431 -704 592 R0 SYMATTR InstName U1 SYMBOL res -64 -448 R0 SYMATTR InstName R2 SYMATTR Value 6.8k SYMBOL res -64 608 R0 SYMATTR InstName R3 SYMATTR Value 680 SYMBOL voltage -1232 128 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 9 SYMBOL FerriteBead -1152 -720 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L7 SYMATTR Value 3.642=B5 SYMATTR SpiceLine Ipk=3D0.2 Rser=3D0.6 Rpar=3D2700 Cpar=3D1.122p mfg=3D"Wur= th Elektronik" pn=3D"742 792 092" SYMBOL FerriteBead 368 -176 R180 SYMATTR InstName L8 SYMATTR Value 3.642=B5 SYMATTR SpiceLine Ipk=3D0.2 Rser=3D0.6 Rpar=3D2700 Cpar=3D1.122p mfg=3D"Wur= th Elektronik" pn=3D"742 792 092" SYMBOL npn -368 -432 R0 SYMATTR InstName Q3 SYMATTR Value 2N4401 SYMBOL FerriteBead 928 -272 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L9 SYMATTR Value 3.642=B5 SYMATTR SpiceLine Ipk=3D0.2 Rser=3D0.6 Rpar=3D2700 Cpar=3D1.122p mfg=3D"Wur= th Elektronik" pn=3D"742 792 092" SYMBOL FerriteBead 864 592 R180 SYMATTR InstName L10 SYMATTR Value 3.642=B5 SYMATTR SpiceLine Ipk=3D0.2 Rser=3D0.6 Rpar=3D2700 Cpar=3D1.122p mfg=3D"Wur= th Elektronik" pn=3D"742 792 092" SYMBOL res -464 -96 R0 SYMATTR InstName R7 SYMATTR Value 33k SYMBOL cap -464 96 R0 SYMATTR InstName C7 SYMATTR Value 10n SYMBOL res -896 -704 R0 SYMATTR InstName R5 SYMATTR Value 1k SYMBOL res -320 -688 R0 SYMATTR InstName R6 SYMATTR Value 10 SYMBOL cap 0 -224 R0 SYMATTR InstName C9 SYMATTR Value 100n SYMBOL cap 96 -688 R0 SYMATTR InstName C10 SYMATTR Value 100n SYMBOL res 1328 128 R0 SYMATTR InstName R8 SYMATTR Value 43k SYMBOL diode -608 -304 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D5 SYMATTR Value 1N914 SYMBOL cap -1040 272 R0 SYMATTR InstName C8 SYMATTR Value 330n SYMATTR SpiceLine V=3D16 Irms=3D0 Rser=3D0.007 Lser=3D0 SYMBOL ind -112 -272 R90 WINDOW 0 5 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName L13 SYMATTR Value 100=B5 SYMATTR SpiceLine Ipk=3D0.29 Rser=3D0.55 Rpar=3D33813 Cpar=3D2.94p mfg=3D"W= urth Elektronik" pn=3D"744043101 WE-TPC 4828" TEXT 368 352 Left 2 !K1 L1 L2 L3 L4 L5 0.999 TEXT 552 104 Left 2 ;| TEXT 552 128 Left 2 ;| TEXT 536 104 Left 2 ;| TEXT 536 128 Left 2 ;| TEXT -728 816 Left 2 !.tran 0 50m 0 10n startup

The LT1431 at U1 now provides local control of the voltage at the emitter of Q3 - the local feedback through R7 and C7 to the REF input of the LT1431 now comes from there, rather than from the top of C6 as in the previous version which avoids the delay through L13.

I've added C8 to kill the high frequency gain around the local feedback loop - 330nF cuts down the switching frequency ripple at the emitter of Q3 to about 20mV peak to peak, and to 8mV at the REF input of the LT1431.

This has let me cut L13 from 4.7mH to a much more reasonable 100uH, and still limit the 230kHz ripple current getting back into the power supply to about 250uA.

There's about 80mA circulating through Q1 and Q2 and the transformer primary, but with good layout you can keep that very localised.

There's another 10mA or so circulating around C8 and the LT1431, but again that can be kept localised.

I can't say that I think that this version of the circuit is anything wonderful, but at least I've dealt with the issues that worried me in the previous version.

Whether this deals with the issues that were worrying Legg, I don't know. Maybe he'll tell me.

-- Bill Sloman, Nijmegen

Reply to
Bill Sloman

Oops, don't know where I remember 15t from.

See:

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Notable consequences:

- More bias current. TIP32 could be higher gain (???) or darlington (3906 + TIP32, or some TIPxxx), or a PMOS for that matter.

- Unconditionally current limited, short proof (though with high dissipation)

- Doesn't have the voltage gain a freewheeling inductor provides; in fact, the resonant voltage peaks will be clipped by the TIP32's C-B junction. (What's the reverse beta of TIP32 anyway?) This will increase distortion at full output...which is a silly thing to be concerned about when there are diodes on the output in this case.

Obvious blunder: feedback is backwards. Sadly, TL431 isn't provided with a "noninverting" input, so another transistor has to be provided to invert feedback. This could be eliminated if, say, a spare op-amp were handy in the implementation. Maybe the LT version has this.

Ah, true -- I notice the base winding typically ends up biased a little below ground. A lower impedance helps recycle some of that, somewhat counterintuitively.

Joule thief, energy scavenger? Doubt it ;)

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
Reply to
Tim Williams

Congratulations.

1) Runs and regulates 2) into the needed load 3) at a frequency close to that demonstrated in the original hardware.

If a TL431 was used, however, there would be issues with this kind of compensation method. Perhaps the LT version doesn't have the same problems - I doubt that models used demonstrate them either, but who knows.

This doesn't get a simulation of the original cute circuit, which would be to-the-point, and of interest.

Even the open-loop stimulus example can be made to oscillate at MHz frequencies, instead of the desired lower range, by starting the 'stimulation' level 400 to 500mV higher than that used in the cute1var3.asc file presented. Such a difference should be irrelevant. Until it's done, the simulations of this circuit are all just a bit of trickery, or slight of hand.

RL

Reply to
legg

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