Good and fast CDS cells

[britt-stinker]

Hey can someone recommend me some good and fast CDS cells to put outside boxes to control different pots? I have some but they are very slow at rising and falling.

Anyone?

[Ge_Whiz]

The problem / advantage of CdS LDRs is that they are inherently slow. It's a feature, not a bug. But how are you using them? As a series resistance, or as part of a voltage divider?

Also note that LDRs vary widely in their resistance range. If you need a resistance less than 1 Megohm, you need to get an LDR with that as a top value - some go to much higher resistance (5 Megs or more).

[britt-stinker]

The problem / advantage of CdS LDRs is that they are inherently slow. It's a feature, not a bug. But how are you using them? As a series resistance, or as part of a voltage divider?

Also note that LDRs vary widely in their resistance range. If you need a resistance less than 1 Megohm, you need to get an LDR with that as a top value - some go to much higher resistance (5 Megs or more).

As a voltage divider. The ones I have go to about 500k ohm i think. I thought that I just got some bad ones(I mean bad for the application I was gonna use them for).

[zachary vex]

perkin-elmer purchased vactrol, which made some very fast and wide-range photoresistors for many years, but as far as i've been able to ascertain, they are no longer selling the individual high-speed cells outside of the vactrols designed for high-speed and wide-range.  it's a sad thing, but we are witnessing the death of an enormous amount of technology in a very short period of time.

[R.G.]

it's a sad thing, but we are witnessing the death of an enormous amount of technology in a very short period of time.

It's what I call MBA disease.

There is a fundamental set of tenets in MBA land that your investments must produce a certain rate of return. Any investments - that is, product and manufacturing lines - that is not returning that rate is underperforming, and should be "redirected". This quickly leads to a sort of lowest common denominator in the market. Whatever sells in big volumes is available cheaply and widely. Whatever sells in lower volumes or cannot be manipulated above the minimum rate of return is not available at all.

There is no love of technology in the MBA mind - only money.

[A.S.P.]

"RoHS" is involved, too.

[R.G.]

Yes, then there's RoHS. There's nothing quite as techie friendly as making it a crime to use any part older than X. 

[no one ever]

it's a sad thing, but we are witnessing the death of an enormous amount of technology in a very short period of time.

It's what I call MBA disease.

There is a fundamental set of tenets in MBA land that your investments must produce a certain rate of return. Any investments - that is, product and manufacturing lines - that is not returning that rate is underperforming, and should be "redirected". This quickly leads to a sort of lowest common denominator in the market. Whatever sells in big volumes is available cheaply and widely. Whatever sells in lower volumes or cannot be manipulated above the minimum rate of return is not available at all.

There is no love of technology in the MBA mind - only money.

thus the need for buying huge lots to get rare items.. thus the need for a representative of a small market to ascertain such lots... thus we must thank the lord for smallbear. 

[Joe Kramer]

Hi!

You might want to try Silonex part #NSL-6112.  Available through Allied Electronics.  I don't have the data sheet in front of me, but in practice, these are pretty fast and responsive.  Added plus, they're small too, about  4mm around.

Joe

[no one ever]

anyone know a part number for CdS cells at mouser.. poring through their catalog, not even finding a photoresistor.

[The Tone God]

anyone know a part number for CdS cells at mouser.. poring through their catalog, not even finding a photoresistor.

Mouser stopped carrying phtotocells about a year ago. Digikey starting carrying cells around that time so hit them up or Smallbear or similar.

Andrew

[no one ever]

anyone know a part number for CdS cells at mouser.. poring through their catalog, not even finding a photoresistor.

Mouser stopped carrying phtotocells about a year ago. Digikey starting carrying cells around that time so hit them up or Smallbear or similar.

Andrew

ahh. that would explain everything. i know about smallbear, but steve doesn't carry lamps and an assortment of other things i need... and i'm familiar with mouser.

i've already got the vibe cells from smallbear...


i'll cease my derailment of this topic. 

[britt-stinker]

To be more speciffic I'm lookin for one to control the delay time on mine rebote delay 2.5. It is allready modded to a very long delay