Failure mode of LEDs in overcurrent situation

Started by Andrew T. in sci.electronics.basics4 days ago 2 replies

I'm curious about what happens to an LED when it is exposed to a moderate overcurrent situation. This question came about as I was...

I'm curious about what happens to an LED when it is exposed to a moderate overcurrent situation. This question came about as I was troubleshooting some small white LED lights I built using 3 5mm LEDs and a current limiting resistor to run on 12Vdc (supplied by a lead-acid battery charged by solar). After some time, many of these strings would start to flicker or blink. I was about to po...


Crimping technique?

Started by Terry Pinnell in sci.electronics.basics5 days ago 3 replies

Is a crimping tool supposed to work on these things? https://www.dropbox.com/s/hnflor5ratjg06s/CrimpingMaleHeader.jpg?raw=1 All of my...

Is a crimping tool supposed to work on these things? https://www.dropbox.com/s/hnflor5ratjg06s/CrimpingMaleHeader.jpg?raw=1 All of my attempts so far have splayed three of the four squashable sections outwards instead of squeezing them inwards. (The exception is the bit that?s already folded.) Using thin nosed pliers I can make a reasonable connection. Although even with that method it...


Roof co-ax amp supply question

Started by Charlie+ in sci.electronics.basics2 weeks ago 2 replies

Hi All, I want to test out an in-line aerial amp and have supplied it with 12V battery and circuit for testing as below glummed from the web...

Hi All, I want to test out an in-line aerial amp and have supplied it with 12V battery and circuit for testing as below glummed from the web and spares. I can build things but am no shakes on real theory. It works well but seems a bit noisy (hiss on stereo) but I have it down at the RX end of the co-ax at the moment prior to going up the roof with it, so that might make quite a difference t...


Ads On the Circuit Board

Started by Bret Cahill in sci.electronics.basics3 weeks ago 1 reply

OK, you take something apart 'cause it's broke and you already suspect it was _designed_ to break. Yer suspicions get confirmation and when you...

OK, you take something apart 'cause it's broke and you already suspect it was _designed_ to break. Yer suspicions get confirmation and when you get inside. The circuit board has a message printed on it: "For a low cost replacement, visit ______electronics.com" Is this common in electronics? Maybe, "for a good time call __________" would be funnier. Bret Cahill


Calculate run time of battery to a specified voltage

Started by AK in sci.electronics.basics4 weeks ago 11 replies

I want to calculate approx run time of a D cell with a capacity of 13,000 Mah. I assume that Time(H) = Capacity(Ah)/Current(A) equals a final...

I want to calculate approx run time of a D cell with a capacity of 13,000 Mah. I assume that Time(H) = Capacity(Ah)/Current(A) equals a final battery voltage of 0 volts which will not work in my case. I need a calculation for an ending voltage of around 2.0 volts. (At 2.0 volts, my clock starts losing time.) Thanks


motor wiring / Keeps starting and stopping

Started by Steve Wolf in sci.electronics.basics4 weeks ago 4 replies

I have motor that was removed from my furnace when a new furnace was installed. I know the motor is good as I replaced it few years. (2 Y...

I have motor that was removed from my furnace when a new furnace was installed. I know the motor is good as I replaced it few years. (2 Y Old). At the time, instead of replacing the motor with a "Furnace" motor for 400 dollars I replaced it with this one for 90 dollars. It worked great until I replaced the furnace. I thought I would now turn it into a grinding wheel. I connect up two wires...


Servo motor recommendation sought

Started by D.M. Procida in sci.electronics.basics1 month ago 2 replies

For my plotter project I have experimented with a variety of different servo motors. Very cheap analog micro servos work very well (I have...

For my plotter project I have experimented with a variety of different servo motors. Very cheap analog micro servos work very well (I have been using Tower Pro SG90s), as you can see from the images on the site, but digital versions do not, because they are too twitchy. I'd like to try with some different digital (more expensive) servo motors to see if the


Misusing a transformer

Started by david eather in sci.electronics.basics1 month ago 6 replies

Just a sanity check if you don't mind. I have a 230v to 30v 1amp 50Hz transformer - is there anything wrong with plugging that into 115v 60Hz...

Just a sanity check if you don't mind. I have a 230v to 30v 1amp 50Hz transformer - is there anything wrong with plugging that into 115v 60Hz to get 15v 1 amp out?


Diode test and identify

Started by Steve Wolf in sci.electronics.basics1 month ago 8 replies

trying to fix AC/DC power plug. I have a Diode that says: GW327 SR560 I THINK this is a Schottkty Diode. Setting meter to Diode test,...

trying to fix AC/DC power plug. I have a Diode that says: GW327 SR560 I THINK this is a Schottkty Diode. Setting meter to Diode test, Im getting, 1.71 Forward and Reverse .171. Normally on diode I know you should get 1 on reverse Are these readings allowable or is the Diode Bad. Thanks.


Harmon divider 10:1 and 100:1

Started by amdx in sci.electronics.basics2 months ago 3 replies

Just found this neat method to make 10:1 voltage dividers. Not as important now that you can get such precision resistors, but with this you...

Just found this neat method to make 10:1 voltage dividers. Not as important now that you can get such precision resistors, but with this you don't need them. Also measurable on a single voltage range so no worry about another attenuator in your meter. Again not so important with modern meters. I had to read it twice to understand it, maybe you will do better. > http://conradhoffman.co


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