Thanks professor, will try your configuration. My configuration is far from yours. I can hardly charge my 1000uF capacitor in place of R0 to above 2V, after 2 minutes of charging with my input at 5V (after a while the red LED won't lit anymore, and I noticed the circuit stops working after a while, because the frequency drops to zero), this shows that there must be something special in your configuration. Have you tried to replace one of your crucial components at a time (Diode, Transistor, Toroid core) and observe significant changes in your measurements?
Clearly, our DUT's are different. I don't know why, but I have some further results to share. I'm working with two capacitors now, 10,000 uF = 10mF each, so a total of 20 mF. Charged to 2.58V using 2 rechargeable AA's. I use the caps to run the device until the voltage drops to 1.5V on the caps and note the time t required using a stop-watch. Thus, I have a reliable measure of Ein and Pin:
E = 1/2 C V**2, P = E/t,
So Pin = 1/2 20mF (2.58V**2 - 1.5V**2) /t = 44.06mJ/t
So 44.06 mJ are put into the system, and dividing this Ein by the time, I derive Pin. The measurements have proven repeatable -- and interesting.
Here are some results this morning:
Basic conditions:
Rb 52Kohms
MPS2222
C-B 151 pF
D red LED
L-B, L-O bifilar 9turns, ferrite toroid 1"OD, ~120uH each
Ro = 1Kohm
Rr= 0, CSRout = 0 (removed)
Oscilloscope ATTEN used to look at the Pin waveform most of the time in my little lab at home.
1. With the above conditions, the caps discharge from 2.58V to 1.5V in t = 37.8 seconds, so Pin = 44.06mJ/37.8s = 1.17 mW.
LED dim but clearly visible throughout the run.
2. Next, I removed the Ro/LED from the system, so current flows back to ground through L1 loop only, t = 37.0 s, Pin = 1.19mW.
A bit of a surprise, repeatedly, with the Ro/LED out of the circuit, without that load, the input power drain INCREASES.
A bit hard to explain without OU perhaps, but not sure. In any case, the power drain through the LED and 1Kohm resistor is small (if not negative
)...
3. So I take the output of L1 and connect it to point 6 (instead of to point 4), so that the return path is through the 1Kohm Rout. Rout/LED back in the circuit.
Now the LED is extremely dim, but visible in a darkened room. t= 52s, Pin = 0.85mW. Pin went down, as might be expected since the current through L1 is impeded by the 1Kohm Ro.
4. Next, change Ro from 1Kohm to 220ohms. Same test as in 3, now t = 62.2 sec, Pin = 0.71mW. Now this is surprising to see Pin go down with Ro reduced, since the current through L1 is impeded LESS by 220ohms than by 1Kohm Ro -- we are approaching the situation in 1 where the L1 output goes directly to ground.
5. Back to condition as in 1, but with Ro=220ohms, t= 38.2 s, Pin = 1.15mW (about the same as with Ro=1Kohm).
6. Next, I removed the Ro/LED from the system, so current flows back to ground through L1 loop only, t = 37.1 s, Pin = 1.19mW.
A bit of a surprise, repeatedly, with the Ro/LED out of the circuit, without that load, the input power drain INCREASES. As before.
Next I went to my own "replication", with the conditions as in 4 above, and found t=54 seconds (0.82mW), rather than 62.2 s with the 1st DUT. So small variations make a difference (not too surprising) -- in particular, the toroid/windings differ in my own replication. But the power draw (Pin) is much less than your Pin, Laneal...
Now, this gives us an idea of how the circuit behaves, and a measure of the low power consumption.
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Topic: Circuit sj1. Terse and Technical only. (Read 165287 times)
