Single Coil Two Transistor Boost Circuits

[MarkE]

OK, that I can understand. Here's the code fully "arduinoized" and tested, runs a nice square pulse with minimal jitter at 104.8 kHz.

//------------------------------------------
//----MarkE's Pulser Code               
//----gives 104.8 kHz
//------------------------------------------

void setup(){
  pinMode(6,OUTPUT);
}
void loop() {
delay00:
  digitalWrite( 6, HIGH )  ;
  goto delay01 ;
delay01:
  goto delay02 ;
delay02:
  digitalWrite( 6, LOW ) ;
  goto delay05 ;
delay05:
  goto delay00 ;
}

//-----------------------------------------

Thanks !

(ETA: This appears to be the fastest with this method, even if I only use a single goto:delay pair for HIGH and LOW, it still runs at 104.8 kHz.)
(ETA2: Atmel 328P)

I am glad that it helps.  I have yet to dig into how Arduino code compiles.  I was hoping that the compiler would be smart enough to reduce the goto's to the next line into RJMP +0 assembly instructions.  It looks like the compiler is inserting overhead of more than 30 instructions.

[Farmhand]

Yeah I'm keen to use Arduino so your code helps me a lot, I might get it out and have a play with it. 100 kHz or so is plenty fast
enough for most booster situations I think. I went down to 30 kHz last night messing about and my little dog started growling at me.
After a while I realized it might be the circuit noise. I wonder what our electronic world sounds like to a dog. Probably very noisy and annoying.  One reason I think I would like to use about 60 kHz or above, surely they couldn't hear that.


P.S. I was writing my previous post before the last two went up I think. Mine looks out of place now a bit. But anyway some might use picaxe. I think micro's are a great way to control and interface separate circuits, as well as they can do a lot themselves.
..

[TinselKoala]

I am glad that it helps.  I have yet to dig into how Arduino code compiles.  I was hoping that the compiler would be smart enough to reduce the goto's to the next line into RJMP +0 assembly instructions.  It looks like the compiler is inserting overhead of more than 30 instructions.

I can't see any big change in frequency when I use 4 or 6 pairs of goto:label statements, and since the main loop with just the write instructions is actually slower than the goto loop, I think that the extra overhead is mostly in the write statements. I might do some additive tests to see how many goto pairs I have to put in before the frequency changes much.

[Farmhand]

I noticed with this circuit that when the load is 3 x 5 mm LED's between the diode output and the positive rail that the ring down is clipped on
the negative side of the oscillations and the very first one seems to have a "charging" type appearance but upside down.
As shown in the first scope shot.

However in the second shot with the load of 2 x AA cells in series between the diode output and the circuit ground the oscillations are free and not clipped.

It appears that if the ring down is "very ringy" when the load is between the diode output and the positive rail some power may be returned. Possibly bringing the ring down back to supply voltage quicker (if there was enough time for that).

Just a small thing I noticed, not sure if my assumption is correct. Just sayin. 
..
Maybe if I connect my scope to the computer I can get better scope shots.

...

[Farmhand]

Tonight's experiment will be to test the run time for the circuit as adjusted shown last post from 2 x 50 Farad capacitors charged to 0.75 volts each,
which is about 14 Joules per capacitor (28 total), I'll put them in series and run from 1.5 volts down to 0.8 volts, which will be 0.4 volts
on each capacitor and about 4 Joules per capacitor (8 joules total). Leaving me with 8 Joules total from 28 Joules to begin with.
So I'll use 20 Joules, and time it. I'll run the 3 x 5 mm LED's as load.
...

EDIT:....

Results: With 20 Joules it ran for 24 minutes before going under 0.8 volts, at 1.5 volts it had 8.3 volts across the LED's and they
were quite bright, at 0.8 volts input it had 7.8 volts across the 3 x 5 mm LED's, not as bright, but still bright to look at and throwing
useful light.

Works out to I think about 0.83 Joules per minute average, and divided by 60 seconds = about  0.014 Watts power draw average I think.

And it kept running for a further 4 minutes when at 0.68 volts the lights went out.

Not bad and thats with an MPSA06 transistor. about 5 on 6 off I think at the start, 1 mH inductor.

..