Whoop! I fried my first LED the other night....

[TheFantod]

....I was testing my A/B box and trying to figure out why the LED's wouldn't light. (I was using a 9 volt outside power jack). I got a 9volt battery and a battery snap and tried testing the leads. Only I forgot to test the lead BEFORE the resistor.

The green one turned orange for a second, then went out. Then I smelled that wonderful electronics burn smell.

So do I get a badge now or what?  Seriously, I'm starting to feel like a pro!

Tim

[Paul Marossy]

I have some red ones that literally blow their tops off when you do that. Done that once or twice.

I recently made a little LED tester that has a current limiting resistor with a couple of alligator clips fastened to a wood base controlled by a momentary switch. Makes checking LEDs a real snap.

[jkokura]

....I was testing my A/B box and trying to figure out why the LED's wouldn't light. (I was using a 9 volt outside power jack). I got a 9volt battery and a battery snap and tried testing the leads. Only I forgot to test the lead BEFORE the resistor.

The green one turned orange for a second, then went out. Then I smelled that wonderful electronics burn smell.

So do I get a badge now or what?  Seriously, I'm starting to feel like a pro!

Tim

I had nearly the exact same thing happen to me too, 2 weeks ago! I couldn't figure out why that happened, then I checked my resistors - I was using 2.2 OHM resistors, not 2.2k resistors. I nearly burned out a 2nd green LED before I figured it out too.

I usually use 2.2k or 4.7k resistors, no matter what size or colour of LED - is that bad? Is there an easy chart to tell you what size R to use?

Jacob

[MoltenVoltage]

Wait til you smoke your first pot - then you get the badge.   

The higher resistance ones smell like Nag Champa!

[JKowalski]

I usually use 2.2k or 4.7k resistors, no matter what size or colour of LED - is that bad? Is there an easy chart to tell you what size R to use?

It doesn't really matter... Just depends how bright you want it. 2.2k and 4.7k sound like good values to use.

[Taylor]

Wait til you smoke your first pot - then you get the badge.  

The higher resistance ones smell like Nag Champa!

I've done this a couple of times. It's a wake-up call that you are way off track with your design when the insides of the potentiometer start glowing red...

edit: Just occurred to me that any girlfriends or non-electronics types reading this post would get the wrong idea...

[served]

Wait til you smoke your first pot - then you get the badge.   

The higher resistance ones smell like Nag Champa!

That's a good one!

And I have to admit that when i was building a Styrofoam cutter, I needed something to control the voltage with, so I made up a scheme to control the voltage. But it was too off, and the potentiometer burned in flames. I think it was around 60V and 8A  That was scary.

[darron]

I have some red ones that literally blow their tops off when you do that. Done that once or twice.

I recently made a little LED tester that has a current limiting resistor with a couple of alligator clips fastened to a wood base controlled by a momentary switch. Makes checking LEDs a real snap.

"alligator clips"... "snap"... i get what you're doing...

Wait til you smoke your first pot - then you get the badge.   

The higher resistance ones smell like Nag Champa!

i come back to the forum after the break and you guys are talking about smoking pot??

[Paul Marossy]

i come back to the forum after the break and you guys are talking about smoking pot??

Smoke LEaD, it's better. (As in LEaD solder)  
     

[sshrugg]

Wait til you smoke your first pot - then you get the badge.   

The higher resistance ones smell like Nag Champa!

Lol! They really do!  I blew up a jumbo sixed RGB color changing one. It made a LOUD pop and blew it's top off. I had it hooked to a battery that I was holding loose in my hand and when I jumped I threw it across the room by reflex. Felt like I should be counting my fingers!

[G. Hoffman]

I had nearly the exact same thing happen to me too, 2 weeks ago! I couldn't figure out why that happened, then I checked my resistors - I was using 2.2 OHM resistors, not 2.2k resistors. I nearly burned out a 2nd green LED before I figured it out too.

I usually use 2.2k or 4.7k resistors, no matter what size or colour of LED - is that bad? Is there an easy chart to tell you what size R to use?

Jacob

Yes.  Look up the max current rating for your LED (most of the ones you probably use are around 20-25mA), and then apply Ohm's Law - R=V/I.  So, if you have 9V power, you divide 9 by 0.020 and get 450 ohms.  That ignores the forward voltage (aka voltage drop) of the LED, so you could probably use a slightly smaller resistor and get a fraction more output, but why?  You probably don't need the extra brightness.  If you really want, the formula is R = (V_S - V_L) / I, with V_S being the source voltage, and V_L being the LED forward voltage.  But do you really need to do all that work?  I don't.

Or, you could use google and type in LED Circuit Calculator, though most of them will want to know the forward voltage of the LED.

Or, since you are probably using a 9V power supply most of the time, you could just use a 1k resistor, and not worry about it.  The only time you really need to worry about maximizing the LED output is if you are going to be shining it through something, or you are using it for a flashlight or something similar, and more output means less battery life, if that matters to you.


Gabriel

[solderman]

E-lytes are better poppers than LED:s

I was testing a PT80 delay circut before I boxed it and I almost sh*t in my pants when it exploaded after about 30 sec. of playing and testing. I turned out that I had installed the 100uF 63V E-lyte the wrong way on the 18V side (MAX1044).

Caution to connect an E-lyte the wrong way can be dangerous and harm your fingers or make you go blind in worst case  

[MikeH]

Wait til you smoke your first pot - then you get the badge.   

The higher resistance ones smell like Nag Champa!

That's a fun one- I've done that before.  And then there's the badge for frying an IC so badly it overheats and melts to your breadboard.  Now that's a good one.

[served]

E-lytes are better poppers than LED:s

I was testing a PT80 delay circut before I boxed it and I almost sh*t in my pants when it exploaded after about 30 sec. of playing and testing. I turned out that I had installed the 100uF 63V E-lyte the wrong way on the 18V side (MAX1044).

Caution to connect an E-lyte the wrong way can be dangerous and harm your fingers or make you go blind in worst case  

Hey.. Thats actually extremely dangerous. In summer, I was making a fire and some how there was somekind of power suplly along the wood. And damn, the whole fireplace blew up, it was a mess, and the sound was pretty loud also.

[liquids]

That's a fun one- I've done that before.  And then there's the badge for frying an IC so badly it overheats and melts to your breadboard.  Now that's a good one.

I've fried a couple of pots on the breadboard...oops.   Bummer, since I tend to have fewer spares of those than the other parts mentioned.  Nothing says 'time to place a new order' to my psyche like when I fry a pot!

More so, it really annoying when you toss said fried pot to the side rather than the 'garbage' container on your workbench, only to try using it some other day on another build, and can't quite get why your build isnt working...not that that has happened to me, I mean, just, I've heard it's happened to, you know, other builders.   

Anyhow, more odd than that, one of my first op amp breadboard experiences resulted in a spark and a chip of the op amp flying right at my forehead to the point of some pain. I did not know that could happen, and still dunno exactly what I did....  So now, at the wifes wise request, I wear my safety glasses when powering a circuit up for the first time...uh, well, whenever I remember amid the anticipation of powering up a newly breadboard circuit for the first time... 

[liquids]

That's a fun one- I've done that before.  And then there's the badge for frying an IC so badly it overheats and melts to your breadboard.  Now that's a good one.

I don't feel so bad now!   

[Taylor]

More so, it really annoying when you toss said fried pot to the side rather than the 'garbage' container on your workbench, only to try using it some other day on another build, and can't quite get why your build isnt working...not that that has happened to me, I mean, just, I've heard it's happened to, you know, other builders.   

Indeed, I have done this and felt very stupid after trying to get something to work for an hour with a burnt pot.

I also have a little graveyard of ICs, from times when a build wasn't working, so I pulled the ICs and replaced them, then sometimes it works and sometimes it doesn't. So I have a pile of ICs but have no idea whether they were the culprit or not, and therefore they might work and might not...

[liquids]

Bummer. 

That graveyard of IC's it's easy to test - at least the most common of dual op amps.  Breadboard a simple buffer circuit for both channels of a dual op amp and connect power.  Audio in, audio out, and if it passes signal on both channels, you should be good.   I'd try it on both channels to be safe, though I've no idea if it's possible one half an IC could be destroyed but the other OK  I'd gather it unlikely.

Anyhow, If you have good fingers or an IC puller, you could verify a bunch of dual op amps in short time.  It might take an evening of your patience depending on how many yuou have, but in the end, it might be like a small order of ICs for free, instantaneous shipping included.   

[JKowalski]

Anyhow, more odd than that, one of my first op amp breadboard experiences resulted in a spark and a chip of the op amp flying right at my forehead to the point of some pain. I did not know that could happen, and still dunno exactly what I did....  So now, at the wifes wise request, I wear my safety glasses when powering a circuit up for the first time...uh, well, whenever I remember amid the anticipation of powering up a newly breadboard circuit for the first time... 

I suppose all these IC explosive incidents I hear about occur because there is some very small pocket of air inside the chip that heats up tremendously with the high current and concentrated temperatures, eventually it needs some more personal space...

My only incidents so far with electronics were:

Blasting the lid of a e-lyte by running it 3 volts above its rated value...
Melting the plastic off of a couple of my thin alligator clip wires by running 3 amps through them (was not in my right mind that day, I suppose - it was like 30 AWG  )
Accidently putting 15V+ on a PIC (Was using a regulator to step it down but I forgot to use the reg output and used the V+ instead) LOUD bang, but no explosions 
Some others I've forgotten, and more to come

I also have the bad habit of keeping all of my destroyed or damaged components because I can't bear to throw them away    They're obviously trash...but...but...

Maybe I just subconsciously keep them to remind me not to make the same mistake?

[jkokura]

My only trashed gear is the LED that I burned out (as mentioned above) and another LED that I broke one of the leads off of by bending it to much where it connected to the LED itself. Still would work, but there's not enough to solder or attach the LED to anything.

Jacob