LEDs

[kazakhan]

I think a 120VAC shock in one arm is fun. It vibrates your arm like crazy! :lol:

I had a lamp years ago that had a brass switch that would give a nice pleasant vibration when touching the switch eventually it developed too much bite (240VAC)

I have never been bitten by high voltage DC. They say your muscles contract and you can't let go. I worked with a guy whose arm caught fire when he was working on a live broadcasting transmitter! :shock:

When I was 5 I stuck a fork in the wall socket and my muscles most certainly contracted, I couldn't let the bloody thing go, I also couldn't breath. It was immense pain, luckily my mother walked past the room a few seconds after insertion and gave my arm a swift kick. Strangely my hand wasn't burned although it was quite red and sore. And of course this incident only increased my interest in all things electrical
I also bent and grabbed a live soldering iron when I was a teenager, the muscle spasm threw me back over 2 metres and left a severe burn on the palm of my hand.

 

[monkeytree]

powerful stungun?

 

[Oznog]

The best way to do this is a high voltage source LED driver. They do make these:
**broken link removed**

You will need a high voltage output transistor to do this. No high wattage resistors, no flickering, and even current regulation.

 

[solidhelix]

ot:what is teh maximum current that will flow on a LED before it blows up?

 

[solidhelix]

ot:what is teh maximum current that will flow on a LED before it blows up?

 

[solidhelix]

ot:what is teh maximum current that will flow on a LED before it blows up?

 

[audioguru]

Hi Solidhelix,
I think that your "submit" button blew-up!

In a 25 degrees C ambient temperature, most ordinary LED's have a maximum continuous current rating of 30mA to 50mA, check their datasheet. New high-power LED's like Lumileds have a built-in heatsink and are rated for up to 350mA or more.

I have some ultra-bright blue and green LED's blinking extremely brightly at 100mA. They have a maximum continuous current rating of only 30mA, but I followed their recommended pulse width reduction and repetition rate in their datasheet to be safe.

I don't think that LED's blow-up. I have never destroyed one but they probably just suddenly stop emitting light without releasing any majic smoke because the junction or bonding wire inside melts. :lol:

 

[lord loh.]

You could use an LED with a large resistor in series or several LEDs in series(This is being done. You do not have to bother about the reverse bias condition..).

The rersistor approach shall waste a lot of power.

You can visit a few sites of LED manufacturers and see if they have any 220v LED...

 

[solidhelix]

@ audioguru

WAHHHH...my "submit" button did blew up ... i just noticed my triple post this afternoon...

Well, i will follow the 25mA - 50mA current rating you said...

I don't think that LED's blow-up. I have never destroyed one but they probably just suddenly stop emitting light without releasing any majic smoke because the junction or bonding wire inside melts.

this is waht my thinking about, if the LED gets hot, will it burn the solder joints or wires?

 

[audioguru]

Hi Solidhelix,
The power rating of an ordinary LED is very low so I think that one would fail long before it would get hot or melt a solder joint.
The max internal temperature for the LEDs I use is only 110 degrees C. Its case would only be warm and its wires much less than the temp to melt solder.

 

[ece_jm]

I believe it's the curent that kills people and not the voltage. And it's different when it's AC or DC. As I remember 100mA for AC and 300mA for DC is enough to kill you. (Regardless of the voltage)

Here's some example:
**broken link removed**

 

[ece_jm]

I believe it's the current that kills you and not the voltge. And it differs when its AC or DC. 100mA for AC and 300mA for DC is enough to kill you. (Regardles of the voltage)

Here's an example:
**broken link removed**

 

[Mikebits]

Electric shock - Wikipedia, the free encyclopedia

 

[DigiTan]

It's going to be a mix of current and timing. In the early muscle stimulation experiments, you would run a specialized electrode directly to the nerve axion and apply pulses of increasing current or pulse width in each trial until you saw a muscle contraction. The minimum current and pulse width requirements to reach the nerve's action potential would be recorded as the Rheobase and Chronaxie; with DC of course being the bigger hazard. Normally the keratin protein skin provides enough resistance to keep outside shocks from inducing currents above the rheobase. But the resistance of wet or injured skin is unpredictable enough that even single-digit voltages might pose a threat under the wrong conditions.

Back on the LED topic, pretty much every discrete LED I've seen would fail above 50mA (continuous). Usually, the light fades or the color shifts before your eyes and then it just never works again. The only exception I know are specialized LEDs like the color-shifting types, or high-powered stuff like XLamps where they're made to draw 100mA or much more. Just choose your components first and the schematic second (instead of the other way around) and you'll be fine.