This thread will outline circuit and component tweaks and improvements to the common blocking oscillator aka Joule Thief. It will present "rule of thumb" techniques rather than a mathematical engineering approach so that it is more palatable to the average constructor. For cohesiveness, it will be locked until the general outline is presented, then it will open to discussion. Acquaint yourself with basic blocking oscillator operation here:http://mysite.du.edu/~etuttle/electron/elect37.htm or at the Wiki site here: http://en.wikipedia.org/wiki/Blocking_oscillatorSearching the web you will find other interesting explanations also entitled "Joule Thief". Some of the subjects discussed will include: Determining the purpose of the blocking oscillatorFirst we need to define exactly what function or functions they would like the Joule Thief or any such circuit to perform. Since different functions require different circuit topologies, we can properly design the optimum circuit once the goal is known. Is the requirement: a) to drain the remaining energy from a single nearly dead AA cell and transfer that energy to a supercap? b) to drain the remaining energy from a single nearly dead AA cell and light a bank of series connected LED's What type of LED's and how many Lumens are required. c) some other requirement or combination of the above. If you don't need to design for a single nearly dead AA cell, and can put several in series or parallel, the topology will change again. Can the batteries be fresh or is the idea to scavenge remaining energy from nearly dead cells? There is no such thing as a one size fits all blocking oscillator or JT design. First the desired use must be defined, input and output current and voltage requirement, then we can set about optimizing various circuit topologies and turns ratio's to accomplish the task. Sizing the magnetics Optimizing the turns ratio and wire type Optimized circuit topologies Speedup networks Base drive requirements
« Last Edit: 2011-01-22, 13:56:10 by ION »
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Topic: Improvements To The Blocking Oscillator (Read 1104 times)
