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40 Threads found on Led Noise
Undervoltage lockout being tickled by weak mains, poor socket connection or a PFC front end problem? Thermal protection toggling due to a die or board level heat issue? Control loop instability? noise issue w/ current mode control at low duty cycles is often a problem, with the turnoff edge coming close to turnon the switch "ringing tail" ma
Nothing is shown regarding the more sensitive side, the phototransistor. Presumably "active" means these are conducting, but I would not assume that this is because of the led illuminating. A shorted-pins on that led would be good diagnostic cut, if that settles it down then maybe the long wire and local EMI pickup is enough to weakly light the LE
If the led is red and has a 1.7V forward voltage drop then the piezo buzzer might not work with only 1.7V. Why not connect the buzzer to 0V and the output of the second opamp instead? Both opamps have a gain of at least 20,000 and might amplify their own noise causing the led to light all the time. The batteries are missing a capacitor (...)
Im trying to build a circuit which flashes leds when there is data transmission on the lines. Instead of using transistors I saw an example of an op-amp circuit that can be used to light the leds since this is much simpler design and I can use a single dual op-amp chip to drive both RX and TX leds. This is the schematic I based my design (...)
Hello, We have got a contractor to do a 100W flyback led driver for us, and we believe that he has not done a very good job. The circuit works but we believe that its performance is compromised in the way that he has done it. The circuit schematic and LTspice simulation are attached. He has used an external current sense error amplifier wi
Hello, Has anybody experienced problems when sending "PWM dimming style" current pulses down wires to leds (wires of length up to 2 metres long)?....I am referring to sending PWM dimming pulses to a 42V, 2.5A led module. Presumably the current pulses should not have too steep sides or else radiated emissions will result?
Hi, I'm working on the led Dimming for automotive. Driver IC : ZXLD1370 Input : 12V led cuttent : 100mA (24V) Boost Mode PWM frequency (15 Pin) : 1KHz This noise is generated in the ZXLD1370. To reduce the noise? Solve other? 113691 ZXLD1370 datasheet
Hi Shahar, I think everything depends on the size of the object and what the background is reflecting to create a meaningful signal to noise ration. For low cost application your can check-out also led-triangulation like it is used to detect a person in front of an elevator or automatic door. How triangulation work you can check-out here: w
Hi all, I'm working on an optical sensor and am looking to increase my SNR. I've constructed a circuit to cancel out led emitter noise with feedback control. PDref monitors just the emitter, while PDsig carries the sensor signal + emitter noise. Feedback consists of integrator -> JFET VCR -> current divider. Please see attached circuit. LT (...)
Hi everyone, I'm trying to build large led panels (3x128 led modules) using WS2801 leds, with data coming from a Teensy 3.0 microcontroller. I'm having difficulties transmitting my Data and Clock signals between the different panels. The three panels have a separate power supply, so I can't transmit my signals directly because of ground (...)
Be careful of led torches (flashlights) as well! Keith
Hello All, I need to design current stabilized led drivers. (Requiring very low noise, low thermal drift of led currents) Main supply voltage is 15V dc led currents are about 500mA each. I also need to adjust the led currents btw 200 .. 600mA individually for each channel. I can use DAC outputs (...)
Dear FvM, Thanks for your reply. So the point is simulation is simulation and real is real?? The code is below (sorry but I do not know how to summarize the code...) LIBRARY IEEE; USE IEEE.STD_LOGIC_1164.ALL; ENTITY DSADC IS -- a delta sigma analog to digital converter PORT ( clock : IN STD_LOGIC; reset : IN STD_LOGIC; data_in
Hi please help !! ....I made a clap switch with an led and it worked fine clap switch as it is shown in the image attached is a clap On only switch and the led goes off fading within a certain time , then I clap again to ligh it on . Now I just wanted to change the led with a DC Fan ...everything went fine but the fan doesnt stop rotating so
Is it true that led car indicator lights (flashers) have to be done with linear led drivers because switch mode led drivers cause too much ringing on the power wires feeding the indicator lights.?. It is quite likely PWM would radiate a lot of noise in the AM band so filtering would absolutely necessary.
My VU meter has an electret mic feeding a preamp so its level is good enough for the LM3915 led driver IC. Please post your LM3915 schematic. Here is mine:
Assalam-o-alekum i am facing problem in using RF transmitter and receiver of 433.92 MHz RWS-371 RF module series Wireless Hi Power Receiver module (RF ASk) TWS-BS RF module series Wireless Hi Power transmitter module (RF ASk) i am trying to transmit high/low pulse by connecting data in pin of transmitter to VCC/ground and by connecting led
For maximum range you need :- max power in required direction ( led input power, focusing optics). For reception, you need max receiver sensitivity and focusing optics + using the minimum bandwidth required, this is to minimise the noise, which is proportional to bandwidth. So with your present baud rate (if satisfactory for your needs), fit a low
I think it is a good idea to use an optically coupled MOSFET driver. In that way, you have isolation as well as the driver section on one chip. Two such drivers are TLP250 and HCPL3120. They are also relatively common and easy to use. So, you can try them.
Our led drivers are just burst mode or on/off control types. How can you tell the difference between the whine from a vibrating ceramic capacitor and the whine from a switch mode inductor.? These are boost and buck led drivers.