Breadboard Bits - Switching Converter

Prototype

This mess of wires is my first operable switching converter. A few too many gator clips, but it works.
For the past several months, I have been learning the intricacies of the design and operation of magnetic and inductive components. While this is seemingly a relatively simple thing, my penchant for full theoretical understanding caused this to take a fair bit of study.

Well, today it finally paid off. A simple circuit, shown, allows me to light up a white LED, which has a 3V forward drop, from a 1.5V battery. The circuit is a rather boring boost converter, zener shunted, run from an astable multivibrator. That said, it seems to work quite well.

This circuit is not going to find its way into Circuit Corner though. While it does work, and I am quite happy with that fact, it is actually a terrible design, simply a proof of concept for my future designs.

And a picture of it operating. A bit fuzzy, because it was very difficult to keep the battery connected and take the picture.
Bigger and better things are on their way after this. I have an idea, that at the time of writing, I have yet to test, that should improve on this design considerably, and make it useful for powering bright LEDs from small batteries.

Boost Regulator

My new boost converter running six LEDs in series. Far fewer gator clips this time, and the big red inductor does not make an appearance.
This is a slight variation of a design that I will shortly be writing a Circuit Corner article about, my 12 transistor regulated boost converter. The regulation is quite reasonable, and can be tightened by increasing a resistor value. I had about 10% regulation while going from unloaded to the theoretical power limit of the component values I chose.

Apparently, suitably low-value resistors for the current sense are not part of my standard complement of parts. As a result of this, this particular circuit has the OC sensor disabled. In this case, running from a 9V battery, the only problem this caused is that I was not able to use the large red inductor (low value, high current) that I used for the last design, as doing so prevented sufficient voltage accumulation to start and caused the switch element to heat up, suggesting saturation and the resulting pull on the positive rail. I am reasonably confident that, if I had a 2.2ohm resistor, the current limiting would work.

I ran a series of 6 high-brightness LEDs (a mix of white and blue) from this converter. Since each LED has a forward voltage drop of about 3V, six in series would require 18V (I measured 16V in operation), well over the 8V that my nearly-depleted 9V battery could provide.