Details please.I would prefer a CMOS gate oscillator RC oscillator.
I tried to avoid extra clutter.ADG736 power supply connections are missing in your schematic.
Well, that's a start. Efficiency sounds higher than 1% though. If you get 10uA @ 5V out for 1mA @ 0.5V in, that's 10%.Getting back to that idea, it mostly worked.
I'm getting about 10µA out of it in broad sunlight, with up to 9V of voltage.
That gives efficiency of about 1%?
:???: 10Ω primary, 7KΩ secondary gives a voltage ratio of about 26.5 to 1The transformer i got is 1:70, 10Ω primary, 7KΩ secondary.
The problem is, it does not self-start and collapses when the secondary gives less than about 5V - it needs to draw just under 1mA from the source to start oscillating.
[snip]
Anything meaningful i can do to improve it?
I use the free version of SIMetrix SIMPLIS.What did you use to simulate it?
I always thought it was the proportion of the number of turns that define the transformer's ratio. How does winding resistance come into play?:???: 10Ω primary, 7KΩ secondary gives a voltage ratio of about 26.5 to 1
It is a mains 220V to 3V transformer.I think the transformer step-up ratio is critical. You could try a small mains transformer e.g. 240V to 3V or 6V, or perhaps wind your own transformer on a ferrite ring.
Thanks, that looks interesting.I use the free version of SIMetrix SIMPLIS.
Probably, but an interesting one.Pipe dream?
Probably, but an interesting one.
It would certainly be easier to just use a few extra photocells.
By now it's obvious that this "free energy" sucks - for the cost of such a boost circuit i can get a pack of watch batteries, each of which could supply that sensor board for about a year.Or a single lithium coin cell... but that takes the fun out of it I guess.
Yes, it's the ratio of the number of turns on the primary and secondary. Sorry for the confusion, I didn't realize you were talking about winding resistance.I always thought it was the proportion of the number of turns that define the transformer's ratio. How does winding resistance come into play?
That's what I thought you meant. The impedance ratio is often quoted, especially for audio transformers, but it's not to do with winding resistance.Or does the Ohms there mean something else?
I've seen the resistances mentioned and the ratio=sqrt(primaryΩ/secondaryΩ) equation here - http://www.dicks-website.eu/fetosc/enindex.htm , but couldn't find where it came from.
I would calculate efficiency as the useful output power delivered to an external load divided by the total power drawn from the photocell.Sustains itself (consumption of 11µA at 2.6V) with 1200µA at 0.39V, 6% efficiency?
Charges 100µF cap zero to 3V in about 1.5 seconds (200µA?) with 1800µA at 0.433V. 72% efficiency?
I'm not really sure how to estimate efficiency - i usually measure how long it takes to charge a capacitor from A to B and go from here.
Is that a valid method?
Then why is there so much discrepancy?
These are raw numbers - it charges that capacitor in a second while being powered externally, so it's 37% for conversion.I'm surprised the charge pump idea works so well! I expected it to have difficulty raising it's own supply voltage.
Now that makes sense, thanks.The impedance ratio is often quoted, especially for audio transformers, but it's not to do with winding resistance.
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