Hero999 said:Sorry I don't know what you're asking and I'd guess that no one else does.
Please cut your post down to the questions you want to ask.
3v0 said:How about attaching a sensor in front of each LED using a Velcro attachment. That would allow you to remove it for servicing.
There's nothing wrong with asking for suggestions. Please don't take this the wrong way. All I was saying that perhaps you should consider shortening your posts and cutting to the point more.crashsite said:Sorry, I wasn't aware that a request for suggestions, rather than a "question" was illegal in this area.
Hero999 said:You can get some pretty small SMT LEDs and have you considered electroluminescent wire?
Optical fibre is good but it doesn't conduct that much light.
mike11298 said:These circuits are so simple anyone can make 'em - blindfolded. all it is is a transistor-as a-switch circuit.
Hope this helps somewhat
Hero, he's looking for ways to attach sensors, not light emitters. He has equipment that will be buried in an enclosure, and he wants to be able to monitor the indicators on that equipment without having to open them and attach wires.Hero999 said:There's nothing wrong with asking for suggestions. Please don't take this the wrong way. All I was saying that perhaps you should consider shortening your posts and cutting to the point more.
You can get some pretty small SMT LEDs and have you considered electroluminescent wire?
Optical fibre is good but it doesn't conduct that much light.
Michael, DG412 is activated by voltage, not current. And they are very expensive if you have to buy them.mike11298 said:Because you intend to have many LEDs you may want to consider an 'analog switch' which is a chip with switches that are activated by current. The advantage of that, is that they dont need an extra resistor where you'd have one at the base of a transistor. Plus they're a whole lot cheaper and smaller.
Roff said:Hero, he's looking for ways to attach sensors, not light emitters. He has equipment that will be buried in an enclosure, and he wants to be able to monitor the indicators on that equipment without having to open them and attach wires.
crashsite said:Yes.
In an ideal world where the manufacturers mount their LED indicators such that they can be plucked off the equipment and relocated, without heroic effort, there wouldn't have even been a question. The LEDs would have simply been extracted and re-mounted on the remote panel and wires run back to the equipment.
Pretty simple in the '70s...virtually impossible in the new millenium. Ah, the joys of progress.
Torben said:You might be able to use some of the thousands of spare LEDs you have as the sensors instead of the slower CdS cells.
crashsite said:Have you done any testing on this and accumulated some data?
Torben said:Nope, but I plan to do some simple tests tonight after the baby's in bed. I'll report back if I find anything interesting, but it sounds like you pretty much already covered it.
I thought it might be too easy.
crashsite said:Be interested to hear what you discover. I did my testing after reading an article in some electronics magazine (back when they were made out of paper rather than bytes of data) and, got a bug in my ear to try it.
Torben said:However, a CdS cell feeding a simple Darlington made of 2 2N2222s works nicely, with a pot to set the input bias as a sensitivity adjustment. It's very sensitive and while not super-fast it seems more than fast enough to give a good visual replication of the hard drive activity light on my laptop (I hot-glued the CdS cell over the LED on the top panel).
crashsite said:Yep, that's pretty much what I was thinking. Actually, I was assuming that, depending on the LED (size, brightness, speed and color) I'd probably end up using a mix of transistors and IC comparators. The comparator especially for trying to capture the light from the bi-color LEDs with filters.
If you've still got a bug in your ear, you might like to try some different colors with cellophane filters. It's been awhile since I saw the color response curve for a CdS cell but it's likely that there are some conbinations that would be tough.
Actually, a chart of the resistance change of the cell with different LEDs and LED/filter combos (either measured directly or via voltage or current changes) would be very useful.
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