#qi-hardware IRC log for Friday, 2017-02-03

sb0hmm does this work? http://laserhacker.com/wp-content/uploads/2013/06/SuperJoule3.jpg00:19
DocScrutinizer05work for what?02:02
DocScrutinizer05the circuit isn't all that clear on its intended purpose02:03
DocScrutinizer05also looks terribly BOM-optimized, with no considerations about *anything* except BOM02:04
Action: DocScrutinizer05 idly wonders if that "laser saber" is meant as an electromagnetic weapon to jam communication or even erase magnetic tapes02:08
DocScrutinizer05meh, had to use some guessing to find http://laserhacker.com/?p=52702:14
DocScrutinizer05that looks like a ferrite toroid, not a rod02:15
DocScrutinizer05meh! sb0, yes it might work, but definitely not nicely02:17
DocScrutinizer05but I think they messed up orientation of primary and secondary coil of transformer02:25
sb0oh yes sure, it's not nice. but does it oscillate at all and drive the transformer?02:27
sb0the secondary circuit is driving the transistor between collector and base, not between the emitter and base as one would expect02:27
DocScrutinizer05yeah, it looks pretty strange03:08
DocScrutinizer05then OTOH B-W vs B-C doesn't _really_ make a difference for AC, only for DC03:09
DocScrutinizer05s/B-W/B-E/03:10
DocScrutinizer05with the coil between B-E you had no bias opening the transistor, and you'd need an additional resistor to create such bias to make the circuit start up03:11
DocScrutinizer05anyway it's a really nasty circuit, that could easily latch up03:15
DocScrutinizer05the components "Light" and "B"(attery) are not really defined and probably complex, with their complexity being relevant in that nasty circuit03:20
DocScrutinizer05maybe the whole circuit is actually only working by operating the transistor in a possibly destructive way.03:24
DocScrutinizer05but *maybe* those schematics are outright wrong03:44
DocScrutinizer05I mean, you can't drain current from a NPN base, you only can dump current into it03:47
DocScrutinizer05the "Light" component actually looks like it might be an LED energy-saver lamp, which means it is a Graetz-bridge with a buffer capacitor behind03:50
DocScrutinizer05this would massively change the way this circuit works03:51
whitequarksb0: oh that's just a joule thief10:22
whitequarksb0: wiki even has a full descrition 10:23
whitequarkhttps://en.wikipedia.org/wiki/Joule_thief#Description_of_operation10:23
sb0whitequark, not exactly, the output is in series with the base10:26
whitequarkah, hm10:26
DocScrutinizer05yeag, it's terribly weird23:49
DocScrutinizer05yeah, even23:50
DocScrutinizer05it has one obvious advantage (if you can call advantages on a defunct design): switching off the load ('Lamp') will immanently switch off the circuit23:51
DocScrutinizer05a joule-thief works via the positive feedback (like basically all oscillators do), so opening the C-E of transistor must make current flow through 'lamp', until transistor eventually switches off (for whatever reason, prolly saturation of the transformer) and then the feedback will need to apply *low* voltage to transistor to make a positive feedback... :-o where does the stored energy in transformer get dissipated then??!, *at 23:57
DocScrutinizer05least* this circuit needs a clamp diode E-B to allow transformer energy to power the 'lamp' while current flows from B through coil to 'lamp' and then to don't know where (mind you C-E closed)23:57
--- Sat Feb 4 201700:00

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