Bob Engelhardt wrote:
Winston wrote:
Bob Engelhardt wrote:
The wiki ckt has a current-limiting resistor in series with the voltage
source. Not so the posted ckt.

It *is* in the posted circuit.
Sort of.

As James mentions, the internal resistance of the PV
cell is the current-limiting resistor.

I meant the capacitor voltage source. Is its internal resistance a
sufficient current limiter? I'm not familiar with super caps, but the
common ones that I am familiar with will supply huge currents, momentarily.


This circuit, yes?

D1
.--||--+-----+---- (+) to caliper
+ | | |
.------. + | |
| | --- ---
| ---- | --- \ / ~~
| | C1| ---
| ---- | | | LED (red)
| | | |
'------' | |
- | PV | |
'--------+-----+--- (-) to caliper


Under no circumstances would the voltage across
the LED (and capacitor) go above, say 1.8 V
because the LED turns any additional
voltage into current. In order for C1 to produce
a current large enough to endanger the LED or
the caliper, it would have to be allowed to charge
significantly above the 'zener point' of the LED.
It just cannot.


--Winston