I looked into the way of doing it in LTSpice, and it can do RMS and MEAN calculations over many cycles. I found that input is 955uW and output is 213uW. Not surprising here. These numbers shows us that a lot of power is spent at the transistor/coil/core/diode. Therefore when we get a n=50% when only considering the power stored in a cap at the output, that is a strong indicator of ou. As I have shown in the other posts, including the power dissipation on the diode might be enough to show ou.
Good points, Lane... and also Gibbs.
The discussion at OU -- note that I found this morning on my variant of Xee2's variant, that the LED dims quickly down (Pinput ~ 700mW), then the LED turns back ON (clearly) while the Pinput has dropped dramatically.
/2 C V**2
So Pinput = 1/2 C (Vstart**2 - Vend**2)/time
= 1/2 10mF (2.8**2 - 1.7**2) / 3.4 seconds = 7.3 mW =
7300 uW (above Vcritical)
Not too exciting so far, but I noticed that the LED came BACK ON at approx 1.63 Volts! Not bright, but clearly glowing. Note that Xee2 on his schematic specifies 1.366V as Vinput, so this would be in the range of much lower power consumption, Pinput.
Note that the power consumption is hundreds of times LESS:
Pinput = 1/2 C (Vstart**2 - Vend**2)/time
= 1/2 10mF (1.431**2 - 1.243**2) / 200 seconds = 0.0126 mW = 12.6 uW !! (below Vcritical)
The input power has dropped by a factor of over 500.
Next I put a 1ohm resistor in series with the LED, and the Pinput dropped to about
9.3 uW. As in "microwatts"!!
BTW, I noticed the same pattern for the sj1 circuit a while back, dimming, then the LED comes back on and glows for a lot longer thereafter. I thought it was just a curiosity when I discussed this with smartscarecrow last week, but now I see this as an important effect -- and very dramatic with Xee2's circuit, a huge reduction in Pinput.
With a red LED instead of Green, the Pinput is roughly the same (11 uW from 1.291V to 1.117V in 200s). The red LED goes OFF at about 1.44 Vin (from the cap) and back on at lower Pinput, at about 1.406 Vin.
Now this is exciting -- but why the huge drop in Pinput at a critical voltage?? I really don't know, but would like to understand. Will some of you jump in and let's see if we can figure this out? My GUESS is that the lower Pinput range is the most interesting in terms of seeking OU.
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Topic: Circuit sj1. Terse and Technical only. (Read 167601 times)
