RadioShack Photocells Data Sheet InterpretationPhotocells

[Fndr8875]

Im low on cash right now and have a pack of these, Id like to just buy the VTL51 or whatever cus that seems to be the optimal one to use in place of home made LDR Tremolos and other pedals that use this sort of setup. Ive read a few post that say to use the largest one in the pack, I tried a magnavibe a while back and had pulsing from led, but something was wrong in that volume drop was so low i could barely hear it unless turning SS 10 watt test amp up to ten. It calls for 5k/20m which in the second half of specs looks like its close enough to those specs. I just dont upderstand the Lux stuff and why the first chart is so low in resistance compared to the second half. There is no info on package. But ive learned recently to copy paste part number from radioshacks website and google that part number and add datasheet after to get specs on something. dont get me wrong I love small bear, but the Vactrol or optocoupler or whatever is $8.75, wtf, why are they so high, small bear is pretty good about having reasonable prices, and Ill pay more for peace of mind ordering from them than ebay, im guessing there harder to find. If anyone can recommend a quality one for say 2 bucks that would really help(if it exist). For now need help translating info above to see if its worth messing with, with these photocells. Im low on cash and just cant make an order right now so gotta use what i got.


Photocells Multi-pack (5)
(276-1657)                 Specifications             Faxback Doc. # 38703

TYPE            ILLUMINATION  @  RESISTANCE   ILLUMINATION   @   RESISTANCE

P722-7R: ......... 1 Lux .....@.. 13 kOhms ..... 100 Lux ....@... 900 kOhms
P722-5R: ......... 1 Lux .....@.. 15 kOhms ..... 100 Lux ....@... 1.1 kOhms
P1201: ........... 1 Lux .....@. 120 kOhms ..... 100 Lux ....@..... 7 kOhms
P201D-7R: ........ 1 Lux .....@. 130 kOhms ..... 100 Lux ....@..... 8 kOhms
P201D-5R: ........ 1 Lux .....@. 160 kOhms ..... 100 Lux ....@..... 9 kOhms

                                  CELL RESISTANCE
          POWER     VOLT.BETWEEN             10 LX            RESPONSE TIME
TYPE     DISSIPATION  TERMINALS   0 LX       MIN~MAX          RISE    DECAY
P722-7R: .. 150 mW ... 200 VDC . 0.5 MOhms . 2.5~7.5 kOhms .. 50 ms . 40 ms
P722-5R: ... 70 mW ... 100 VDC . 0.5 MOhms . 5.3~15 kOhms ... 50 ms . 40 ms     
P1201: ..... 70 mW ... 100 VDC ... 5 MOhms .. 20~60 kOhms ... 40 ms . 30 ms
P201D-7R: . 100 mW ... 200 VDC .. 20 MOhms .. 23~67 kOhms ... 50 ms . 20 ms
P201D-5R: .. 50 mW ... 100 VDC .. 20 MOhms .. 48~140 kOhms .. 50 ms . 20 ms

Coating: ...................................................... Resin (All)

Voltage betwee Terminals @ 25 degrees C............................ 100 Vdc

Power Dissipation @ 25 degrees C..................................... 70 mW

Ambient Temperation Range (C).................................... -30 - +80

Spectral Peak............................................... 540 nm typical

Cell Resistance 0 1x....................................... 5 M Ohm minimum

Cell Resistance 10 1x.............................. Min 20 kOhms - 60 kOhms

Gamma 100/10.................................................. 0.75 typical

Pre-historic Error (Change PE) @ 1 1x............. +0.10 for 30 sec typical

Pre-historic Error (Change PE) @ 1 1x............ +0.15 for 120 sec typical

Color Temperature Error (Change CE @ 10 1x).................. -0.15 typical

Response Time @ 10 1x................................... 40 ms Rise typical

Response Time @ 10 1x.................................. 30 ms Decay typical

Specifications are typical; individual units might vary. Specifications are
subject to change and improvement without notice.

[Fndr8875]

magnavibe schmatic


http://i605.photobucket.com/albums/tt137/pinkjimiphoton/MagnavibeSchemsmall.jpg


Verolayout

http://tagboardeffects.blogspot.com/search?q=magnavibe

[smallbearelec]

If you happen to find any among the RS ones that work for your job, great. It's chancy, because what goes into those packs is whatever surplus RS's buyers happened to find available. They're probably perfectly good parts. However, the resistance range--especially the dark resistance--might not be ideal for you.

Yea, the pre-assembled VTL-type modules are expensive. The price reflects both what they cost us and also the fact that they are guaranteed to hit within known specs. But look at these photocells: http://smallbear-electronics.mybigcommerce.com/photocells-cds-5mm-diameter/

They run less than a buck each. The 9203, in particular, is known to work well in 'vibe-type circuits. Combine one with a green 3mm LED

http://smallbear-electronics.mybigcommerce.com/led-t-1-3mm-water-clear-high-brightness/

and roll your own module. Can be done with heat shrink and epoxy glue, or I have these headers:

http://smallbear-electronics.mybigcommerce.com/headers-and-covers/

Later edit: Try the P201D types. The 20 meg dark resistance of those looks good.

I hope this helps.

[Fndr8875]

I wasnt implying that small bear was jacking up the price, hell an ebay search shows 1 us seller, for 10 bucks, and some from china for 22.99 each. Ive made orders from most of the pedal selling sites and IMO yours is always right on the money in terms of what i expect, im still new to this hobby so, but the 90 cent lm301 made an awesome Rat. I make stupid errors, or lets call them beginner or errors bc my eyes are burning from starting at shit til 3 am, and it stings to do so on and expensive part when your poor like me. Payday comes and ill be hopefully getting the vtl5c2 optocoupler, a Ca3080, and or some matched Fets. Wanna do a Fat fuzz factory so bad, but my Rat has quenched my thirst for over the top dist/fuzz....Oh yea your Alumium Knobs...i want some with the smooth sides, but i can figure out which ones they are called, from memory one is called diamond something and forget the other but what are the ones with smooth sides called?
But again i wasnt implying your prices were unfair, just the part itself was pretty expensive. Considering there is a boss tremolo for $50 bucks thats practicly brand new at my local GC. But whats the fun in that lol??

[PRR]

> dont upderstand the Lux stuff and why the first chart is so low in resistance compared to the second half.

Lux is light level. IIRC, 1 Lux is dim indoor light and 100 Lux is very bright indoor light.

With an LED right at the photo-R, inside a closed black box/tube, you can probably go below 1 Lux and above 100 Lux.

Resistance range-- The magic stuff is moderately expensive and bulky. A higher resistance cell is smaller and cheaper. But sometimes a lower R cell saves other costs enough to be worth it. That's why both kinds are made. Depends what you are doing with them.

Remember these photo-resistors are NOT made for audio use. 99% of sales were for outdoor light dusk/dawn switches and for burner flame-out detectors. In these applications very wide parameter spreads were not very important, and smooth linear change was not needed. Around 1959 some audio-spec photo-resistors were on the market, making some interesting products (LA2a limiter, Fender tremolo), but the audio market was never large and often found other ways to do their thing.

The price- this type photo-resistor has been BANNED (Lead and other toxic metals) for sale in Europe as part of new equipment. The ripple effect is that US makers do not want this type photo-resistor in their inventory, for fear it might get to Europe and be fined. It seems to be widely available and made in/near China, but for burner and lamp control, so production spreads may be very wide and specs way off the mark.

Yes, Bear's prices for VTL parts are near market, even a bit low. His no-name generic photo-resistor seem to be a better grade of the burner/lamp market parts and that price looks very low (surely smart buying, not bogus parts). The Radio Shack price is twice what it should have been some years back, but RS has been slow to adjust price when a part gets scarce, so may be a good buy this year. OTOH RS's buyers are clueless, so you never really know what their suppliers have stuffed in the bubble-packs.