R2 = 3k ohms

R3 = 10 ohms

C1 = 680 pico Farads rated for 1000 volts (I don't like this high voltage

rating)

C2 = 47 micro Farads

Q1 = NTE12

Q2 = NTE11

Input = Two Eveready "C" Nimh cells, v=2.52 volts, i=116 mA. They

discharge at fairly stable voltage.

Output = Two Nichia white leds in parallel,

LED1: 3.46 volts, 24.8 mA,

LED2: 3.41 volts, 27.1 mA

I'm using an FP ferrite bead. Hole=.184", length=1/8", OD=3/8".

I don't know

what kind of ferrite it is. I got it from Hosfelt Electronics for 15 cents.

I have more test results for the two transistor circuit.

I swapped the NTE11 for an ECG128P. It started well but the output led

current dropped about in half. Then I switched to rechargable alkalines

instead of Nimh. I got a little more output current but it started harder.

I switched back to NTE11 / NTE12 and made a new coil with

about 40 turns

instead of 20. I got about 15 more mA through the leds so

I increased R2 to

5k to get 27 mA in each led.

Next I varied C2. With 47 micro F it almost doesn't run. I can

jump start it

but then it fades and goes out.

With C2=4.7 micro F it runs fine after a jump start by pulsing R2 to 3k.

Without C2 it starts perfectly.

Results:

NTE11/12

R2=5k

C2=4.7 micro F

LED current = 27 mA each (3.5 v)

Battery input = 3 volts, 122 mA with C2=4.7, 116 mA with no C2.

Light quality = high

There's some kind of pattern emerging here. The 47 micro F

capacitor works

fine with the one transistor circuit, then for the two transistor

circuit, as the

number of coil turns increases, there's a preference for a lower

value C2.

A larger coil might mean lower frequency so maybe lower

frequencies like

smaller C2 values. There's a little more light, but not much more,

with the 4.7

micro F C2 compared to no C2.

I guess I gotta go find a smaller C2 capacitor. What is another

size C1 to try?

Is there a size relationship between C1 and C2?

There isnt really any size relationship

between C1 and C2, except when ripple

is a concern.

For the purpose of understanding C1 a little better, Q2 has two

distinct states:

1. Q2 turned on

2. Q2 turned off

When Q2 is on, C1 charges very quickly though the base emitter of Q1

and through Q2 collector emitter.

When Q2 is off, C1 discharges through the 10k resistor.

At very low input voltages like 1.2 volts, R1=5k does appear to

work better then 10k.

A value of 500pf appears to work with inductor values from

200uH to 3200uH, but i would try 1000pf with larger inductances

also. Stick to 500pf or so for lower inductances.

Apparently, the lower the value of C1 the lower the ripple output.

I think I've got it.

It seems to be starting very well under all conditions. I think there is
a

relationship between C1 and C2.

Here's two things:

1. Sometimes my brain doesn't work very well. One of my capacitors,

the 4.7 micro F, is a polarized electrolytic. I tried hard, but for some
of

my testing, I had it in backwards. Sorry.

2. It's starting right up now with C2 = 47 micro F. I put a second 680

pico F capacitor in parallel with the first C1. That gives it a little
more

something that I've got to think about, but it's working. It starts right

up. Zoom.

Q1=nte12

Q2=nte11

R1=10k

R2=5k

R3=10 ohms

#leds = 2

2 x 1.5 volt batteries

C1= two 680 pico F in parallel

C2= 47 micro F

D1=nte585

Here's numbers for the two transistor circuit using a 47 micro F filter

capacitor on both the battery side and the LED side:

Two Alkaline batteries in series:

Vbattery = 3.06v

Ibattery = 114.7 mA

LED1: i=32.8 mA, v=3.58 volts

LED2: i=35.6 mA, v=3.54 volts

Two Nimh batteries in series:

Vbattery = 2.46v

Ibattery = 72.5 mA

LED1: i=18.5 mA, v=3.37 volts

LED2: i=16.6 mA, v=3.35 volts

Ibattery with and without the inlet filter capacitor was almost identical.