replace LED with relay that activates large LED panel

Started by Fernando Cassia in sci.electronics.design4 years ago 6 replies
LED

Hi there, I have a circuit that, under some circumstances, lights a LED. The problem is that the LED is too small and can only be seen while...

Hi there, I have a circuit that, under some circumstances, lights a LED. The problem is that the LED is too small and can only be seen while in clos= e proximity of the circuit. What I'd like to do, is keep the LED in place, but add some additional circ= uitry after the LED so the original LED keeps functioning, but when it dete= cts the led has voltage applied to it, drive a relay that ...


Blinking LED controlling small relay - issues?

Started by xpzzzz in sci.electronics.design6 years ago 6 replies
LED

I have built a circuit that uses a flashing LED (flashing function built- in) to control a relay; the relay resistance is the current-limiter for...

I have built a circuit that uses a flashing LED (flashing function built- in) to control a relay; the relay resistance is the current-limiter for the flashing LED. Do I need to worry about voltage spikes killing the LED, and if so, is there a simple way to prevent that. LED 5V, 12v supply. This works now, but it would be nice to know if it will not break two weeks from now...


Re: Auto Base LED replacements

Started by admiralsmead in sci.electronics.design2 years ago
LED

You could give one of these a...

You could give one of these a try. http://www.aliexpress.com/item/3W-BA15s-LED-Car-Light-Bulb-24V-12V-3014-SMD-LED-BA15s-Lamp-Singl e-Contact-Bayonet/32525056686.html or http://www.aliexpress.com/item/UAU-LED-33-LEDs-LED-DC-12-v-110v-220v-E27-Sinais-de-volta-Reversa -luzes/32499870127.html the trick for LED replacement of a incandescent bulb is to have many SMD LED around the bulb, not just a cou


What does a "self-ballasted" LED mean ?

Started by Anonymous in sci.electronics.design3 years ago 7 replies

Could some electronics guru pleas explain what a "self-ballasted" LED lamp mean ? I have seen LED lamps, running off the AC line, and...

Could some electronics guru pleas explain what a "self-ballasted" LED lamp mean ? I have seen LED lamps, running off the AC line, and powered by a simple small 5V 1 Amp SMPS, but what exactly does a self-ballasted LED lamp mean ?


single switch on off and mode select

Started by panfilero in sci.electronics.design5 years ago 7 replies
LED

Hello, I'm trying to come up with a way to only have one button, and use that to power my circuit on and off, and also to flip through...

Hello, I'm trying to come up with a way to only have one button, and use that to power my circuit on and off, and also to flip through different modes of operation. For example, my circuit is suppose to blink an LED in different patterns, click it once, turns on LED is on click it again LED is blinking slow click it again LED is blinking fast click it again LED is blinking slow (any ...


Correcting a LED response curve?

Started by Jacques St-Pierre in sci.electronics.design10 years ago 61 replies

Hi, I am designing a product using a Vactrol (led controlled resistor) to simulate a RTD. The led intensity will be control by the buffered...

Hi, I am designing a product using a Vactrol (led controlled resistor) to simulate a RTD. The led intensity will be control by the buffered output of a D/A chip. It is working, but to be useful, we have to operate the led in the worst region of it's curve, resulting in very coarse response. Since I do not have enough resolution on this D/A to correct that from software I am searching ...


LED string - does it matter where the resistor is?

Started by unk in sci.electronics.design2 years ago 1 reply
LED

powering a string of three leds with a current limiting resistor - can I go LED - R - LED - LED ?

powering a string of three leds with a current limiting resistor - can I go LED - R - LED - LED ?


simple led dimming circuit

Started by Anonymous in sci.electronics.design4 months ago 9 replies
LED

Hi everyone, have a project where I need a simple LED dimming circuit to make a 20 mA UV LED brighten and dim slowly at about 5 or 10 Hz (LED...

Hi everyone, have a project where I need a simple LED dimming circuit to make a 20 mA UV LED brighten and dim slowly at about 5 or 10 Hz (LED needs 3.5-3.7 V). Any suggestions? Only thing I could think of was some kind of 555 circuit but that is just due to my limited experience. Scot


those LEDs from mid 1980..

Started by Nils in sci.electronics.design3 years ago 8 replies
LED

That other thread about LEDs reminded of something I have observed a few days ago. I was in need for an additional indicator LED to debug...

That other thread about LEDs reminded of something I have observed a few days ago. I was in need for an additional indicator LED to debug someting. Since it is only a temporary thing I picked an old leaded 3mm red LED out of my 'assorted parts' junk box and soldered it right beside another, new red LED. The old LED must be from the mid 80th and hasn't seen much use. At least I remember ...


Replacement LED?

Started by DaveC in sci.electronics.design2 years ago 51 replies
LED

The LED in my flashlight is blinking (2/sec). It?s not the support circuitry (constant current): the voltage across the LED is constant 4v. I...

The LED in my flashlight is blinking (2/sec). It?s not the support circuitry (constant current): the voltage across the LED is constant 4v. I presume it?s a failure mode of the LED. It happens immediately upon power-on. http://imgur.com/a/rIRDG The form-factor is close to a 5x5mm (h x diam). Standard through-hole leads. But it?s a pretty high-intensity one. Don?t know what m


Lighting a LED with a candle flame

Started by Jan Panteltje in sci.electronics.design5 years ago 34 replies

Lighting a LED with a candle flame After reflecting on the circuit 'oscillator running on home made thermocouple', and failing to get a LED...

Lighting a LED with a candle flame After reflecting on the circuit 'oscillator running on home made thermocouple', and failing to get a LED lighting up yesterday, it all fell into places, and I realized that the means to obtain the required 2V DC for the LED WAS ALREADY THERE. For the curious and experimenters, here is the complete diagram: http://panteltje.com/pub/lighting_a_LED_with...


PSpice Netlisting/Template Trick

Started by Jim Thompson in sci.electronics.design5 years ago 7 replies

Just discovered (or re-remembered :-), in PSpice... To just have the color of an LED showing in the schematic (I hate over-klutzy drawings), I...

Just discovered (or re-remembered :-), in PSpice... To just have the color of an LED showing in the schematic (I hate over-klutzy drawings), I just enter color and the template collects the model name... Template= X^@refdes %1 %2 My\@COLOR\@LED COLOR=RED LED=LED ...Jim Thompson -- | James E.Thompson | men...


LED output vs bias current

Started by George Herold in sci.electronics.design4 years ago 20 replies

So I was shinning some Cree leds onto a photodiode and measuring the photoc= urrent. Here=92s a plot (opamp bias current ~20pA subtracted from...

So I was shinning some Cree leds onto a photodiode and measuring the photoc= urrent. Here=92s a plot (opamp bias current ~20pA subtracted from data.) https://www.dropbox.com/s/atyo4uvsb09fgd7/LED-PD.BMP Below about 1mA of LED bias current the photo current increases as the 3/2 = power of the led current. Which was totally unexpected! (I expected linea= r.) I=92m making up a hand-waving ...


LED question

Started by panfilero in sci.electronics.design6 years ago 4 replies
LED

Hello, There's this schematic I've been looking at and I can't figure out why they are using a FET and two resistors to light up an LED which I...

Hello, There's this schematic I've been looking at and I can't figure out why they are using a FET and two resistors to light up an LED which I believe is suppose to indicate that the device is on. The device is a guitar effect pedal. I'm have a hard time figuring out when the LED comes on, and also why the FET is there, and the parallel resistor. What I'm talking about is located towrds t...


Haunted By LED Light

Started by amdx in sci.electronics.design6 years ago 38 replies

I'm haunted by LED light! When I wake up there's the LED on the cordless phone charger and the LED display on my alarm clock, also two LEDs...

I'm haunted by LED light! When I wake up there's the LED on the cordless phone charger and the LED display on my alarm clock, also two LEDs on the VCR. I walk in the bathroom there are 3 LEDs on the toothbrush, I walk down the hall and there is a second toothbrush with it's 3 LEDs, then I hit the dining room, where my modem has 5 LEDs and the router has another 6 LEDs plus the Xbox PS h...


LED drivers and itty bitty transformers?

Started by mkr5000 in sci.electronics.design6 years ago 6 replies

Ok, so I buy one of these led driver modules off of ebay, made in china -- they work great and will drive up to FOUR 1W power led's in series at...

Ok, so I buy one of these led driver modules off of ebay, made in china -- they work great and will drive up to FOUR 1W power led's in series at 350ma. The transformer in this thing is really small, maybe a half inch square. It has a 120v input and who knows what out. Something I think I need to bone up on are DC to DC converters because this is where the magic lies, correct? So, if this ...


Fading LED circuit with 555 timer.. LED stays on..

Started by Phil in sci.electronics.design7 years ago 3 replies
LED

Hi, I've built this circuit: http://www.555-timer-circuits.com/up-down-fading-led.html On a breadboard and I'm struggling to get it...

Hi, I've built this circuit: http://www.555-timer-circuits.com/up-down-fading-led.html On a breadboard and I'm struggling to get it functioning correctly. The LED just stays on.. How can you tell if the 555 timer chip is working?


simplest offline circuit to power a small LED for a short time

Started by Jamie M in sci.electronics.design7 months ago 32 replies

Hi, I would like to make (or find an off the shelf device) that can power a small LED for a specified time ie adjustable from 1 to 30minutes,...

Hi, I would like to make (or find an off the shelf device) that can power a small LED for a specified time ie adjustable from 1 to 30minutes, after the main 120VAC power is disconnected. The LED brightness should degrade over that time, starting at full brightness, and then to no light after the specified time. The circuit should also be able to operate down to -40C. The LED initial p...


LED on Photodiode step response

Started by George Herold in sci.electronics.design7 years ago 163 replies
LED

I=92 looking at the step response of a photodiode (PD). I=92m stepping the current into a LED such that the step doubles the photo current from...

I=92 looking at the step response of a photodiode (PD). I=92m stepping the current into a LED such that the step doubles the photo current from the PD. (I=92m not starting with the LED off, but on slightly.) Here=92s a =91scope shot. The bottom trace in the PD response. (The top is the voltage step to the LED (through 100 ohms)... AC coupled to get rid of a big DC offset.) http://img18...


Circuit request - digital led clock (studio timepiece)

Started by Anonymous in sci.electronics.design5 years ago 5 replies

Hi ALL, I have no design knowledge but a little understanding and the ability to put a circuit together. My soldering etc. is reasonable. I...

Hi ALL, I have no design knowledge but a little understanding and the ability to put a circuit together. My soldering etc. is reasonable. I really really really would like to put together a digital led clock with: Analog style round face with digital led time readout in the middle ie ... 22:10 12 static hour leds around the face 60 sequenced leds for seconds led t 12 always on. ...