Let there be light

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Sceadwian

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Woke up early and had some time to kill, never did anything with mains before so I whipped this up for amusement. Also goes to show what having a large bag of idle 15000mcd LED's will do to a bored person.
Two sets of 40 LED's in series, one wired in inverse parallel. The flickers a bit much (at least for me) but it's served it's purpose of amusement, and that first thrill of plugging something into a wall without it bursting into flames.
 

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Krumlink said:
I hooked up a speaker to 24VAC and you could hear the 60hz before it melted and broke down.
Click to expand...

Years back, me and a friend connected a speaker directly across 240V AC mains - stood well back, and turned the power on!. The cone entirely left the speaker and flew across the room
 
Krumlink said:
was this during your younger, wilder years
Click to expand...

You young kids have got to realise, that it's all been done before, long before you were born!

And Audioguru was probably doing it, even before I was born!
 
Has anyone ever heated up a vacuum tube grid 'till it glowed like a night light?

Has anyone ever intentionally fried a tantalum cap in order to evacuate the workplace, thereby getting out of some work time?

Has anyone ever left their workplace PC running during the lunch hour with a text-to-speech program continuously repeating "xxxxxx is an a$$hole" whereby xxxxx is the name of the department supervisor?

Has anyone ever connected the center conductor of a 75' high, 80m dipole to the shop teacher's metal desk?

Has anyone ever charged up small, 200v electrolytic caps and left them lying about on the lab tables?

Has anyone ever entered numerous formulas into a programmable caculator that was allowed for use during a test?

 
Ive done that before, I had some 330V 10 uf caps that were still charged when I put them into my sorters. I then had the nasty repercussions when I needed one of em 2 seconds later. The voltage was 275 roughly, from a disposable camera flash board, just put the cap between the capacitors leads and it will charge up.
 
kchristie, there was no need for one. The voltage drop is 124 volts, slightly more than the RMS voltage of the outlet, I calculated the RMS current was going to be 8ma's (this is a linear asumition I'm not sure how the diode no linearity will tweak the RMS ma's). I bought them as a lot so I'm asuming they're closely matched. Even the worst case scenario of the 170 volts across them that's only 4.25 volts per diode, it's a bit high but the peak is so short it's not hurting anything.

From what I gather LED rope light uses a setup very similar to this. I actually used more LED's than I needed just to be sure I didn't burn them out.
 
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Nigel Goodwin said:
And Audioguru was probably doing it, even before I was born!
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I am still doing it. I enjoy doing it. Hee, hee. I am still a dirty old man.
Oh, electronics?
I have never blown up a speaker or a resistor or a transistor or a diode or an LED because I believe in max power ratings.

Nigel, I was born in August, 1945 just after the official WW2 ended.
I think Hitler's war was WW2 and Japan's war was WW3.
Was Japan just taking advantage of the concentrated effort in Europe?
Boy oh boy was Japan taught a lesson, twice! BOOM, BOOM!
 
Audioguru, the Japanese war started in the 1941's (pearl harbor) and the war in Europe for the Americans began in 1943 ish (invaded Europe in 1944, invaded Africa in 1942, but the European war was going on/started in 1939). It is all perspective of how you look at it.

What was your reaction when the IC came out? I bet it blew your mind
 
audioguru said:
Nigel, I was born in August, 1945 just after the official WW2 ended.
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WOW.. You are old (no offenses).. You were 47 years when I borned...amazing
You're like my grandpa.. just that he actually don't even know how to turn on a computer.
 
I worked for Philips in Canada when they made a two-transistors Schmitt-trigger IC and some RTL logic ICs. Then DTL logic ICs.

I saw their first compact cassete player and it later became a recorder.
I saw their first dim LED.
I saw their office "computer" that used punched cards for its program and core memory (little ferrite donuts on crossed wires).

The Philips Canadian head office blew my mind. Its foundation was made from thousands of obsolete old car radios.
 
Voltboy said:
WOW.. You are old (no offenses).. You were 47 years when I borned...amazing
You're like my grandpa.. just that he actually don't even know how to turn on a computer.
Click to expand...

Hey Voltboy, how old do you think the people who designed, built and flew the mission to the moon were!

If thinks look advanced to you today it's because today's designers stand on the shoulders of giants

Lefty
 
Going back to the original LED post, I took apart a (yes broken) LED exit sign once. It had a current limiting resistor on it though, probably in the 5W range if I'm remembering correctly (which I'm probably not).

It had a nice SCR circuit too to detect power loss, had a reset button and everything.
 
I am not old. (62)
I am just not as young as I used to be.
I feel almost the same as when I was young.
Some old people act and feel very old.
 
Krumlink said:
What was your reaction when the IC came out? I bet it blew your mind
Click to expand...
Back in 1980 I worked for an electronic supply store that was owned and started by a guy who worked as young engineer under Alexander Graham Bell, designing vacuum tubes as well as with Whestinghouse Corp. He told me numerous stories of him making vacuum tube audio amplifiers and delivering and installing them via horse and buggy to distant towns. The old guy used to just hang around the business and fuss with the silliest things like a poor rolling caster on a cart and would whine a lot. But, he was the owner! He'd come to the service shop and start arguments about solid state versus vacuum tubes. Once when IC chip technology was mentioned, he started yelling and throwing his arms about almost in a fit of rage! His looks resembled Colonel Sanders of KFC. He was so frustrated with the advancement of electronic technology... yet as a R&D engineer for Bell Labs, he was in on the ground floor of it way, way back!! We referred to him as the "Colonel" when he'd come into the shop to pester us.
 
I normally use series resistors with LEDs, the worst I've ever done is connected up three 350mA LEDs in series to a 9V.
 
As I said, the RMS voltage for the diode array was covered plus 4 volts. Diodes are forgiving devices, and in reality it's the junction temperature that is the true limiting factor. The peak inverse was covered less transients and surges. No resistor was needed. For real world applications the wire resistence, capacitive and inductive reactance would have regulated the maxium current well bellow the failure mode of this particular diode 'structure' Otherwise they wouldn't use them in LED rope lighting, mind you they're cuttable at every half phase voltage level (couple feet usually)
 
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