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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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26th Sep 2019, 10:12 am | #61 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,013
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Re: Your first experience with LEDs?
I think the sales boom for LED watches was more due to Kojak.
Not many could afford the Omega one! |
9th Oct 2019, 6:37 pm | #62 |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Re: Your first experience with LEDs?
Some early tri colour leds, a cds photocell, and a couple of nice military standard panel indicators, on with an nve filter
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9th Oct 2019, 6:41 pm | #63 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Your first experience with LEDs?
I remember those DIL-packaged sets-of-LEDs - I built a battery-condition indicator for one of my cars using one of those and a chip - LM39something - that was specifically designed as a driver for such applications - there were 2 versions, one log, the other linear; the log ones were invariably used as level/drive-indicators in recording applications and transmitter modulators.
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9th Oct 2019, 6:48 pm | #64 | |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Re: Your first experience with LEDs?
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9th Oct 2019, 6:51 pm | #65 |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Re: Your first experience with LEDs?
The chinese are all over them
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9th Oct 2019, 6:53 pm | #66 | |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Your first experience with LEDs?
Quote:
I remember that you could even at one time buy those DIL "Bar-graph" LEDs which had the first 6 or 7 LEDs green, then a couple of orange and finally one red, specifically for use with the 3914/3915 chips. |
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9th Oct 2019, 7:12 pm | #67 |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Re: Your first experience with LEDs?
Definitely, we had test sets with lm311 comparator and resistor chains to do a similar thing
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10th Oct 2019, 4:46 am | #68 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
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Re: Your first experience with LEDs?
Wasn't there also an LM3916, which was a similar bargraph driver with yet another response curve?
You could also get at one time little PCBs with the LED and LM3914 dice directly on the board and bonded out to each other. A dozen or so external connections to the LM3914 connections other than most of those for the LEDs. RS did them, I still have the datasheet. I have one used as a battery condition indicator in a piece of telecoms test equipment (Tester 301B), one of the LEDs or its connection has failed alas. It's not important (it's used in bar rather than dot mode, so the missing LED simply appears as a gap in the bar and I can still tell when the battery needs charging) but I'd like to replace it. But finding a replacement is hard, it pretty much has to be the original module to fit in the space. |
10th Oct 2019, 6:31 am | #69 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
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Re: Your first experience with LEDs?
I've seen cassette decks where one bargraph driver IC was multiplexed to drive two rows of LEDs alternately.
The design confused me at first, because there did not seem to be an oscillator controlling the switching, nor any transistors that looked good for the full current .....
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If I have seen further than others, it is because I was standing on a pile of failed experiments. |
10th Oct 2019, 8:31 am | #70 |
Hexode
Join Date: Jul 2010
Location: Royal Berkshire, UK.
Posts: 470
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Re: Your first experience with LEDs?
I built a power amp a good few years back using a pair of LM39** to drive a couple of bar graphs as VU meters.
Cross-linking the cathode from LED 1 to anode of LED 2 and so on, up the chain gave a wonderful fade effect, where the upper-most LED would be dim, the next one down, slightly brighter and the 1st LED nice and bright, for example. At full tilt with a hearty beat the effect was obvious, too loud and the whole bar graph would flash. Mark
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Slowly turning the 'to-do', into 'ta-dah' |
11th Oct 2019, 2:49 pm | #71 | ||
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Your first experience with LEDs?
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24th Oct 2019, 9:41 pm | #72 |
Heptode
Join Date: Jul 2010
Location: Wellington, New Zealand.
Posts: 653
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Re: Your first experience with LEDs?
My first LED was in a watch of which I was mightily proud as it seemed to futuristic. One point about car/bike ignition systsm is I have allways wondered why they do not use some variant of the pizeo electric ignition buttons as on gas torches or barbecues. Surely some sort of drive off the car timing belt and cam operating a pizeo button could achieve the spark with using a battery or electronics (save for the pizeo circuit) at all.
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24th Oct 2019, 10:48 pm | #73 | |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,129
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Re: Your first experience with LEDs?
Quote:
For ignition in an engine, many millions of operations would be needed rather than a few thousand. |
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24th Oct 2019, 11:07 pm | #74 |
Retired Dormant Member
Join Date: Dec 2006
Location: Wickham, Hampshire, UK.
Posts: 107
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Re: Your first experience with LEDs?
Think I'm going to have to dig out the vintage LED collection, it's been while since I last looked.
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27th Oct 2019, 3:10 pm | #75 |
Diode
Join Date: Nov 2016
Location: Bedfordshire, UK.
Posts: 2
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Re: Your first experience with LEDs?
First one was a 3mm red in the '70's sometime, from RS. It was used in a logic probe - a design from one of the magazines that used a 7400 as a flipflop to extend the pulse.
Later I got some of those claw-shaped monsanto 7-seg displays referred to earlier with the intention of making a DVM (never completed, though I may still have the display board). |