Sourcing LDRs

[Timko]

The Duelin' Herbies has been my proverbial Waterloo. I burned out a board trying to troubleshoot one this winter.  But since I drilled the enclosure (and it was a lot of frilling), I ordered a new board from Chris, hoping to get this one right. After some more troubleshooting, I finally got the LEDs functioning like they should. But I still got not envelope effect. So I measured the LDRs I had sourced (some GL5528s), and boy are they off. The values are supposed to be around 10k with light and 1M with dark, but these were going over 10M dark. I tested about a dozen of the ones I got and all were about the same.

So I'm interested how people source LDRs to ensure they are sent a part in the specs they are after. I either ordered them off of Amazon or eBay (probably the latter). Are there particular eBay dealers that are more reliable than others?

[Yahoo67]

I am in the same boat as you Timko! I ordered a kit off eBay a while ago for cheap and after a couple of build that didn't work properly I decided to test them.... And boy they were all off.

I have seen many people post that they source them from futurlec but never have tried them personally.
https://www.futurlec.com/

Just search ldr on the search bar and you got a couple of options. They are a bit more expensive than eBay ones but are still kinda cheap so that's nice

Hope that helps !

[jimilee]

I used Tayda ones, I read Chris' documentation and went with that. You are covering them before testing them in the build aren't you?


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[m-Kresol]

I am in the same boat as you Timko! I ordered a kit off eBay a while ago for cheap and after a couple of build that didn't work properly I decided to test them.... And boy they were all off.

I have seen many people post that they source them from futurlec but never have tried them personally.
https://www.futurlec.com/

Just search ldr on the search bar and you got a couple of options. They are a bit more expensive than eBay ones but are still kinda cheap so that's nice

Hope that helps !

I had very bad experience with futurlec the one time I ordered from them. Never again. If you can, try to avoid them

[Timko]

I used Tayda ones, I read Chris' documentation and went with that. You are covering them before testing them in the build aren't you?


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I am actually testing the LDRs that I have in my stash not in the build.  I couldn't figure out why I was getting little to no change in the effect from the Envelope even though the lights were working as they should, and I was only getting noticeable LFO effect with the Color cranked. 

I used GL5528s which should fall in line with the 10k/1M paramters.  Mine seem to be more like 100k/10Ms.  The Tayda KE10720s seem to be in the 10k/500k range. 

[LaceSensor]

futurlec have a great selection but prepare to wait a long time

[Timko]

I measured my GL5528s again in ambient daylight, then used a wooden covering to block out the light.  I stuck them into my breadboard then used a multimeter to test the resistance.  I was consistently getting 5k/300k light/dark readings. 

I also tried out some of the Tayda LDRs I ordered a few months ago and noticed that they were no where close to .5M dark.  They were more in the 200k range.

Do you all have a different method of testing LDR ranges when you do builds?  I generally don't test them but feel I need to start with every build like this going forward.

[Timko]

I did some more testing this evening, this time with the GL5516s that I have.  The data sheet says these should be between 10k and 20k for light resistance, and somewhere in the 0.5M range for dark resistance.  My office has windows on all 3 sides, so I opted to do this after 8:30 when the sun had set. In my rig, I'm using a green diffused LED to measure light resistance connected to a 390E resistor (that's what's in the Duelin Herbies, my current LDR project).  I then cover the light and LDR in this little wooden box, totally isolating it. There's a switch where I can turn the light off and on. I measure the resistance of the LDR in ohms on my multimeter. I bet the light is well north of the 10Lux setting as I was getting light resistance values in the 1.5k to 3k range.  But the dark range was still well north of 20M, and kept increasing until my multimeter was out of range to read it anymore.

I found a data sheet for the GL5516 which state the dark resistance is "Refer to the resistance ten seconds after the 10Lux light is shut up."  If I wait 10 seconds, the multimeter will be out of range to measure these things.  Is there something I'm missing here regarding the dark resistance of these things?  I assumed I was going to get something in the 400k-600k range and find the ones that matched.  Do I even care about the dark resistance?