Measuring LDRs an on going headache

[Flying]

I have two bags of GL5516 LDRs bought from two different suppliers on ebay, using my multimeter and shoving the LDR in a dark drawer I'm getting a reading of about 4M ohms from one lot and 6M ohms from the other. KE-10720 LDRs seem to be beyond the measuring capability of my multimeter.

Using one of those transistor/component testers I can watch the resistance of one of the GL5516s climb up 14M ohms in 9 seconds before going beyond the range of the tester.

The data sheet for both of these LDRs says the dark resistance is 500k.

Am I making a stupid mistake in measuring them? I can't see how two different types of LDRs from 3 different suppliers could all happen to be so far out of spec!

Any thoughts on what I'm doing wrong? Or if you happen to have any G5516s could you measure them to see what readings you get. Thanks.

 

[Bricksnbeatles]

Maybe the drawer isn’t dark enough?

 

[Robert]

GL5516 should measure around 500K dark resistance.

 

[Flying]

Okay, so I'm not doing anything stupid, a GL5516 in a dark environment should measure close to 500k.

I just find it very hard to imagine two different suppliers sent out the wrong LDRs, maybe there was a bad batch. I'll order some more and see what I get.

The multimeter is still on and it's now reading 20.97M ohms.

 

[Flying]

Just got a new batch of GL5516 LDRs, using two different multimeters and a component tester I'm getting dark readings of:

5-6M ohms on the component tester.
3-4M ohms on one multimeter and
3-3.5M ohms on the other.

The value drifts quite a bit hence the ranges.

The specs say 500K.

I can only source from ebay as no component supplier like RS, CPC or Rapid sell them (I'm in the UK).

I fear this curtails any further projects that use LDRs as I just don't know what I've got, unless I'm just not testing them correctly. I would love to know what measurements you are getting as I just feel I must be doing something wrong as surely 3 different suppliers of GL5516 LDRs can't all be sending me the incorrect ones.

 

[Robert]

When I was ordering GL5516's in bulk (a few hundred at the time) there was always a fairly large percentage of them that tested in the meg ohm range.

My guess is that they just aren't sorted very well.

 

[uranium_jones]

OK, so I measured some that I got from Amazon and I wasn't getting a stable reading. I figured that I was doing something stupid but apparently it could also be the LDRs. Gives me a new thing to try again this weekend.

 

[fig]

...and now for something almost completely different

I have a bag of lasers....now where is that box of hamsters?

 

[Flying]

The GL5516 is for the delegate compressor, I just don't feel is behaving quite right, maybe it's the GL5516, or the LED, but as I can't seem to get hold of any GL5516s that are anywhere close to specification I guess it's a case of putting it to one side for the moment.

I might have a go at the diamond Comp as I already have the vactrol for that.

So over to you Fig, what's the plan with the lasers?