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Regarding Light Dependent Resistor

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shermaine

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May i know what is meant by R and R dark for LDR specification?
And if i were to use for spot light, what should the range of R i should use?
And what is meant by spectral peak, Lux and footcandle?
What information do i need for my spot light use to search for suitable LDR?
Please advise. Thanks.
 
If you just want to switch on the spot light at night, the specs aren't too important.

The LDR has a low resistance in light, and a higher value in dark, and all values in between. You can change the value with a resistor in series or parallel if needed. For a simple switch, I'd go for the cheap, since I don't need to know precisely how much light is falling on it, like a light meter.

There are tons of 'Dark-Activated Switch' circuits on the web, several here in the threads. Shouldn't be hard to find on to build/study. Remember several sites with lengthy descriptions about the circuits.

How come you have a red square under your name? Mine is green...
 
Look at the properties of the squares.
A red square means he has a negative reputation.
A green square means you have a positive reputation.
 
LDRs have one of the greatest dynamic ranges of any electronics component. They will go from less than 100 ohms in bright light to over 100M ohms in jet-black darkness. I made a light-tight box for experimenting with LDRs when teaching my electronics class and needed to make connections from outside to inside the box. It was made from opaque black plastic and I drilled holes, mounted and interconnected a solderless breadboard connector inside and out to two opposite sides of the box, one for the LDR and the other for a light source. I ended up having to paint the inside of the box, all the seams and the inside solderless connector with flat black model paint to kill off the light leakage. The LDR could "see" it all. Interesting. I had to have the students set up a voltage divider using the LDR and then use a DMM to measure the drop across the series resistance and then Ohm's Law to calculate the LDR resistance in total darkness since DMMs were limited to 20M ohms max.

Dean
 
Click one the User CP at the top left hand side of the screen and a link to the posts you got reputation will appear.

Your posting history doesn't look too bad but I do notice that you sometimes use text speak, for example in your above post you've written hv when it should be hv, perhaps that's why?

Text speak makes posts harder to read, I tend to just ignore posts that I can't understand but if I'm feeling nice I will tell people.
 
LDR volume control

MIDI instruments sound robotic/ soulless; lacking dynamic variations.

I used to play the accordion for years and albeit I'm keen to enjoy MIDI instruments, so far their "dead" dynamics put me off...
For instance, I have got those great BigFish "Play the Tango" sound samples of each button of the bandoneon.
I also have got a 120-button accordion bass (box section only; i.e. without the bellow) wired to my Roland D20 Synth.. The question is: how to add volume variations, the way accordion/ bandoneon players do with bellow movements while playing the bass buttons?

Since my both hands are occupied playing buttons and keys, I have no hand free to vary the volume control (for vibrato and volume variations). Foot control is far too inaccurate for expressing rapid, accurate vibrato variations.
Since my 120-button accordion bass is attached to brackets on left side of the Synth, I was thinking of suspending it via gentle springs. Then only a lever to a volume control would be needed.
By shaking or pressing up & down the whole 120-button bass box I could vary the vibrato and volume rate as needed to add realism to any MIDI instrument.
Ordinary pots won't last; I suppose a mechanical/ electronic solution is what I'm after. Years ago, I saw a pedal from an Elka organ, which had a v-shaped slot through which a bulb light hit the LDR. Maybe there's a way of doing the same even more efficiently with a special opto-coupler? I have got an old PC-mouse, whose rubbered steel-ball often failed to drive the two little perforated plastic wheels. If I'm not wrong this type of optocouplers in there might be the answer... The volume variations have to be pretty responsive or sudden in order to create vibrato as applied by bandoneon (tango) players (?) I plan to just add this volume control at the output of the PC's soundcard.

I'm grateful for any useful advice on this idea. Now that I'm retired I have at last time to live out my dreams. :) jjj333 from Chile
 
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You can buy a motion activated, dusk to dawn controller for like $15 USD at a hardware store. If you buy the right brand you can find individual parts in some of them, making them very possible for modification, if that's the thing you're looking for... Most of them are being made like el cheapos and use those black blob IC's surface mounted.
 
Whilst it's possible, I very much doubt that you'll find one of those black blob ICs in a dawn to dusk switch because it's such as simple circuit and the fack that they work at mains voltages and not run from a battery.
 
Hero999 said:
Whilst it's possible, I very much doubt that you'll find one of those black blob ICs in a dawn to dusk switch because it's such as simple circuit and the fack that they work at mains voltages and not run from a battery.
at least you don't have to replace batteries, :D
 
Searching the Internet, I discovered that Yamaha built a breath controller (Model: BC3 ...sounds like a trani) for $80, but this thing requires another gadget to translate it to MIDI. Price tag: with shipping & import duty $300+. Since I need only to control the soundcard's stereo output, DIY is my idea. Does anyone of you wise men have a clue how this BC3 breath controls works? I imagine, that it must be some type of fine, flexible plastic gate, flap or membrane, sensitive to slightest air movement, which controls the brightness of a light.

I guess, I'll have to experiment until I get one such gate logarithmically controlling light from a bulb/ LED to an LDR, which then controls another 2 bulbs/ LEDs with an LDR (each) to control the soundcard's stereo output.
In case it doesn't work out with breath control, I still can use it with the 12-bass box (as already described).

Any suggestions on that are "willkommen", for there might be even better/ shorter way to Rome...
of which I didn't think; 100 brains are better than 1 :)
===============
Progress Report: Since nobody of you experts was able/ willing to help me, I googled my head off and discovered that the Morley stereo volume foot pedal circuit could do the job. I designed a breath controller (idea) for it:

**broken link removed**Instead of the piston, a rubber membrane (cut from a condom) could push the slider (using silicon).
P.S. Anyone interested in the easiest method of playing MIDI music is invited to d/l my PDF instructions at: **broken link removed**
 
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