What is Ldr: Definition and 25 Discussions

RdlD RNA (regulator detected in LDR-D) is a family of small non-coding RNAs which repress the protein LdrD in a type I toxin-antitoxin system. It was discovered in Escherichia coli strain K-12 in a long direct repeat (LDR) named LDR-D. This locus encodes two products: a 35 amino acid peptide toxin (ldrD) and a 60 nucleotide RNA antitoxin. The 374nt toxin mRNA has a half-life of around 30 minutes while rdlD RNA has a half-life of only 2 minutes. This is in keeping with other type I toxin-antitoxin systems.Northern blots showed that ldrD and rdlD are both transcribed and primer extension analysis showed the rdlD transcript is not translated.
Homologues exist in related Enterobacteriaceae such as Salmonella enterica and Shigella boydii. The Ldr peptide genes that have been discovered are thought to have evolved from a common ancestor.

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  1. Zeynaz

    LDR circuit electricity question

    So far what i figured out is that R2 and R3 are in parallel, R1 and LDR in parallel. And these two parallel circuits are parallel to each other ( tell me if I am wrong) The voltmeter has to read 0 but I am not sure how i can achieve that. Is there a rule where when the resistance of each side...
  2. D

    What is the operation principle of the LDR?

    Homework Statement Construct suitable circuit and record your finding to illustarte the operational principle of the sensors: sound, light Results: Distance from light source (cm) - light intensity (lx) 0 - 1000 10 - 400 20 - 260 30 - 200 40 - 190 50- 180 experiment involved moving a...
  3. R

    Selective Incident Headlight Intensity Measurement

    Hey guys, I am trying to come up with an idea to measure incident intensity of headlights from an oncoming car for one of my uni projects. This wasn't specifically assigned project topic, we get to choose what we want to do. It's my Instrument and Measurement unit, and I had this idea thought it...
  4. T

    Measure LDR Light with Microcontroller - 10bit Resolution

    I have a micro-controller with 10 bit resolution. How can I convert the voltage or digital output of the microcontroller to a Lux reading ?
  5. RaulTheUCSCSlug

    Creating a Line Following Robot with Arduino and Mindstorms: A Six Sigma Project

    I'm looking to build an Arduino that is capable of following a line depending on a colored strip on the ground, either black or white. I think I might use a LDR, but not quite sure where to even start to be honest. My office is having an Arduino contest, and I just want the Arduino to carry...
  6. C

    Transistor Logic Gate : NOT Gate Explanation?

    Hi everyone. I would like to ask about this light sensor using not gate circuit. I use LDR as an input and a LED as an output. I have tried this circuit in Proteus, and it works. When the LDR 'off', LED turns on, and vice versa. But i don't really understand about the working principle of this...
  7. C

    Extremely low on resistance LDR?

    I need a variable AC attenuator and the only thing I can think of is an LDR. However I would need the on resistance to be very low, less than 10 ohms. I've only found LDRs with on resistances of 100ohms minimum. Is it possible to go lower than the listed minimum is I use a really really bright...
  8. bradzyc

    Simple LDR Circuit problem....

    Hi guys, Right a really simple question here and I'm missing something really basic. I have a simple LDR circuit that I can't seem to get working. I'm completely adept at Electronics and it's use is just for a small project I'm working on in my spare time. Attached below is a picture of the...
  9. W

    Circuit Components-Potential differencd across LDR (photoresistor)

    Homework Statement The following figure shows a potential divider circuit made up of a LDR and a variable resistor R. It is used to activate a buzzer circuit which sounds only at 2.6V and above. The resistance of the variable resistor varies from 100ohm to 10kohm while the resistance of the LDR...
  10. A

    Potential Divider: R(R+r)*E=V - Wrong Ans Explained

    Homework Statement http://puu.sh/dzujr/dcf208c4a5.png Homework Equations Potential divider concept--> R(R+r)*E=V The Attempt at a Solution When there is low light, resistence of LDR increase to produce light. So, voltage across LDr increases and voltage across thermistor decrease-->lower...
  11. C

    Appropriate arrangement of light meter circuit with LDR and resistor question:

    Homework Statement If you have a series 'light-meter' circuit with a cell EMF of 12V that must include both an LDR and a resistor only (in series), which way would you put them around to make this most effective and why? ~~~That is, would you have LDR then resistor, or resistor then LDR...
  12. K

    Can an LDR Detect X-Rays for Bounce Back Conditions?

    Can LDR detect the X-Rays? Please help me. If it does, I have to make the x ray detector for bounce back conditions.:confused:
  13. M

    How to design and construct a LDR

    please describe in amateur terms I am building multiple circuits and want to house these in a toy car for recreational purposes ( the project not the toy lol ) thanks
  14. R

    How Does Liquid Depth Affect LDR Readings?

    1. The problem statement I'm currently conducting an investigation into how a Light Dependent Resistor changes depending on the depth of a liquid above it. The experiment is pretty simple, however the write up is somewhat more problematic. Firstly I'm asking whether I should read voltage...
  15. P

    The affect of changing Light intensity on Resistance due to LDR

    I've got an experiment coming up where I have to find out how the resistance in a circuit changes as more layers of 'tracing paper' are added onto a LDR i.e. as more paper is added the light intensity will fall and as a result the resistance through the circuit will increase. I am testing for...
  16. C

    LDR Circuit Projects - Ideas for Science Fair

    Hey everyone, My teacher assigned my group with working on any LDR-related (Light Dependant Resistor) experiment/circuit. I haven't worked with these resistors before, so I was wondering, what kind of projects can I do? And is there something flashy that will attract people at our science...
  17. B

    LDR: Why is conductance proportional to log(intensity)?

    I am doing a experimental report on various solid state devices and have come unstuck on my work with LDRs. I have data relating conductance of a CdS photo-resistor to intensity of (white) light. The problem is that I am completely unsure as to why there is a log relationship, as has been...
  18. E

    Can an LDR be used in a proximity sensor for coursework in Advancing physics?

    Homework Statement I am just about to start my AS level Advancing physics - Sensors coursework. I was wondering whether it would be a good idea to build a proximity sensor using an LDR in a potential divider. I would reflect an LED off an object, and move the object at different...
  19. A

    How Does Light Wavelength Affect LDR Output in Plant Growth Lamps?

    Homework Statement it is a reasearch project i have to plan an experiment to find what effect different wavelengths of light, from a lamp which is used to grow plants, will have on the output of an LDR. Homework Equations The Attempt at a Solution so far my plan is (breifly) to...
  20. D

    Wavelength and resistance of an LDR

    Homework Statement Light Dependent Resistors appear to have a spectral response; that is, at different wavelengths of light, the LDR will become less resistant than at others. For example, a cadmium sulphide LDR has a high response at 550 as shown at...
  21. C

    What Can We Learn About LDR Sensitivity From Strobe Light Experiments?

    Ive gone about doing an experiment without thinking about what I'm actually trying to find out (result of poor planning) and I am now in a bit of a pickle. My experiment involved an LDR in a circuit connected to a digital oscilloscope (picoscope). I placed a stroboscope 100cm away and set...
  22. C

    Cathy's Question: Motor on/off with LDR and Resistor?

    I've no idea how to start the following question so any help or guidance would be really appreciated. A potential divider circuit is set up with a LDR and a fixed resistor, R. The LDR has a resistance of 200 Ω when it is light and 2500 Ω when it is dark. A motor is set so that it comes on if...
  23. F

    Light Dependent Resistor vs. Phototransistor

    Hi, I'm wondering what the difference between a light dependent resistor and a phototransistor is. Am i correct in assuming they are the same if the third lead of the phototransistor is not connected to anything? Thanks!
  24. C

    Engineering Designing Circuits with LDR and NTC :smiley:

    hello everybody, my teacher:mad: wanted me to design a few circuits like these; 1) an electronic termometer, 2) a circuit that switches on the lights and pulls the pitches in evenings by using circuit elements like LDR and NTC. pls help me :rolleyes: