1 transistor step up-Need help !!

Can anyone draw me a simple 1 transistor step up circuit to power +/- 3 white LEDs from one AAA batt. ?
I know you should use a certain coil...
So, is it possible to draw a little circuit and provide me all the neccesary component info (coil: wich ferrit diametre, wich wire diametre in mm, how many turns, how to wire,...)
Thanks!

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by electronic wim:
Can anyone draw me a simple 1 transistor step up circuit to power +/- 3 white LEDs from one AAA batt. ?
I know you should use a certain coil...
So, is it possible to draw a little circuit and provide me all the neccesary component info (coil: wich ferrit diametre, wich wire diametre in mm, how many turns, how to wire,...)
Thanks!<HR></BLOCKQUOTE>

Here it is. Good luck. Let me know how it works. http://edusite10.tripod.com/led3/onetran/single_tran.html

I am planning on modding my Mag AAA during summer holidays.

Henry

Hi
I have a couple of these kinds of things running on my bench. I used a ferite torroidal core about .250" in o.d., and 34 ga magnet wire, with about 20 t on the feedback winding, and 35 t on the "inductor side". I use a 2n2222a transistor, with 220 ohms in the base. The shottly and cap increase brightness considerably, but the cap only jas to be a .22 uf (film cap) to work. This thing will work down to about .4 v. Make sure you use a Shooky diode. 1n5819 is a good place to start. I have driven two diodes in parallel, but the total light output is about the same as with one LED getting all the current. Remember the phase of the ffedback winding has to be opposite the "drive winding. If it doesn't work when ya turn it on, reverse the two wires in the feedback wirning (connected to batt + and the resistor. Hope this helps. These little things are fun to play with.

I've been playing with the satcure circuit, too. I cut the "throttle" resistor down to 47 ohms and am running it on a fairly depleted "C" cell. It seems to work with a wide range of cores and turns. Seems the fewer turns, the higher the freqency it operates at. Of course the coil will handle more power at higher frequencies, but the transistor and diode get less efficient. I have one operating with only 4 turns on each coil on a 3/8 inch toroid and the freqency is higher than my meter can measure (200K). I also tried a coil with 19 turns for each coil and it was operating at about 40K(different core), and one with 9 or 10 turns was operating at 130K. All the cores I've been using are fairly high permiability as in one turn is about 2 or more microheneries. I'd really like to see an explanation of how this circuit works similar to MrAl's explanation of the brinkman circuit. I'd like to optimize it, but I've got to admit at this point I'm just trying things.

That's interesting information. I've always wondered how critical the number of coil windings is and how much variation is acceptable for the capacitor size.

In a related discussion at, CPF/Electronics Forum. Bat.../satcure circuit, I attempted to explain how a satcure circuit works. I'd like anyone who can to check what I said and either confirm it or correct it. Thanks

Start with the switching mode of a transistor; if you bring the base voltage close to the emitter's
voltage the transistor goes to cutoff; only a little leakage current will flow. Bring the base voltage
closer to the collector's voltage, and the transistor goes into saturation, and the transistor will
only drop a small fraction of a volt and pass a lot of current.

In the satucure circuit, the primary of the transformer is connected to the collector of the
transformer and the secondary is connected to the base.

When the transistor is conducting, current will flow thru the primary. As long as the field in the
inductor is expanding, a current will be generated in the secondary which pushes the base
voltage closer to the collector voltage, quicky putting the transistor into saturation and
maximising the current thru the coil.

When the inductor is saturated, the field ceases to expand and so the voltage that was being
generated in the secondary stops; the voltage to the base is not held so high, and the transistor
drops out of saturation. This reduces the current thru the primary, and the inductor's field starts
to collapse. The collapsing field generates a voltage in the primary, which boosts the voltage to
the LED. The collapsing field also generates a voltage in the secondary, but this time the reverse
of the voltage generated earlier; this time the generated voltage pushes the transistor's base
toward the emmitter's voltage and further reduces the current thru the transistor, reducing
current thru the coil, collapsing the field faster and pushing the transistor into cutoff until the
field has totally collapsed.

At this point the base is no longer being driven toward the emitter voltage, the transistor comes
out of cuttoff, and current from the emitter again begins to flow thru the collector and coil. The
field begins to build, and we are back to the initial condidtion.

The inductance of the primary coil slows the rise and fall of the current, and is the primary
determinant of the frequency at which the circuit will oscillate.