Utilitarianism, (n.)

[no one ever]

It's about 7:00 pm in wintertime in southern California.. and the power goes out. It's completely dark, no light except the moon's beams and neighboring cities' glow, and we've nothing but a lantern and a few candles to light our way through the house.

What do I do in such dire straits as a hobbyist-junior-E.E.?



Measure my Univibe's LDR's in the now-darkened garage with said lantern. 



I thought I'd share my notes: (ordered from Smallbear, original datasheet unknown)

Dark Resistance: >17M  (  )

Light Resistance: 560, 650, 700, 750 ( twas different for each one )

::Take considerably more time to climb in resistance then they take to decline. Went from >17M to .01M in one flash.

::I think my flutter measurements are way off... they measured at about 1k to 15k.

::Test method: photocells held diagonally in tabletop vise, with rubber boots on each jaw for insulation. Leads wrapped around probe's rings (air is a poor dielectric? ). Flashlight w/ momentary switch used as light source in 50^o garage.



Couldn't find a datasheet, so I thought I'd make my own. 

[Peter Snowberg]

In the words of Monte Burns.....

Excellent! 

[no one ever]

In the words of Monte Burns.....

Excellent! 

thank ya 

[no one ever]

Let's assume my flutter (rapid on-off) measurements are off by a factor of 10 (10k-150k)... do I have typical photocells? 

[jrc4558]

That's a large range, but not unheard of. Some photocells I had we going from few ohms to almost 6 megs...

[no one ever]

That's a large range, but not unheard of. Some photocells I had we going from few ohms to almost 6 megs...

Hmm. Well I know my 1k-15k must be wrong.... hopefully.

[Peter Snowberg]

Vactrols have a rather amazing range. Running 1mA through a VTL5C4 gives a range of 1.25K to 400 Megs!  If you're pulling 40mA through the cell (not likely in a pedal) the low end of the range drops to 75 ohms.

Response varies all over the map.