DOD 250 Reissue LED Mod Help

[Gregmon79]

Hey all, first time poster here on DIY. I modded my 2013 DOD 250 (the yellow one w/o LED) tonight. I swapped out the footswitch for a 3dpt and installed an LED. Everything went in ok. I got my parts through analogman.com. I plugged it in, the LED flashed blue and then turned, or should I say burnt, out. I knew right away that it blew. The pedal still functions and works as it should, so I know it's all hooked up correctly. I emailed mike at analogman and he said LED's need a resistor and directed me here to DIY. So, can you guys help me? What do I need to do to get an LED to work properly in the 250? Thank you for any input and help!

[deadastronaut]

oops!..fizzzzzz...

just replace the led, but this time add a 4.7k resistor to the + side of it...(the longer leg of led)

and drop it in where you had it ok. you'll be up  running.

[Gregmon79]

oops!..fizzzzzz...

just replace the led, but this time add a 4.7k resistor to the + side of it...(the longer leg of led)

and drop it in where you had it ok. you'll be up  running.

Awesome, thank you sir! Much appreciated.

[Gregmon79]

Ok, so i got a new LED. Put it in with 4.7 ohm 1/2 watt resistor. Nothing. Pedal works fine. LED wont light. I dont get it. I used a 5mm blue LED 5v 30ma 300 mcd. Is this the wrong LED? I also bought another LED, a red 5mm 12vdc 20ma 1.5mcd. Is it the wrong LED??

I hooked it up, same as the last one with the negative lead going to the 3pdt and the positive going to the positive on the power supply. Color me stumped

[deadastronaut]

4.7k  not 4.7ohm..

get a bog standard led 2.4v .....you dont want 12v leds, or even 5v...


you want the 4.7k from the positive (long leg) of the led going to the resistor then to 9v...otherwise it'll blow again..


9V---/\/\/\/\ -------- + 0--------- ground..
         4.7k               led

[Gregmon79]

Oh snap. Well that would explain it. Jeeezzzz I'm a dope. Thank you.

[Gregmon79]

Can you tell me what a bog standard means?

[Gregmon79]

4.7k  not 4.7ohm..

get a bog standard led 2.4v .....you dont want 12v leds, or even 5v...


you want the 4.7k from the positive (long leg) of the led going to the resistor then to 9v...otherwise it'll blow again..


9V---/\/\/\/\ -------- + 0--------- ground..
         4.7k               led

Its says 4.7kohms for the resistor. Is that right?

And the LED, what specifically am i going to need? 

Sorry, I'm really new to all this.

[bluebunny]

Can you tell me what a bog standard means?

Rob means just a plain old raw LED.  The 5V and 12V parts you've mentioned have a resistor hiding inside the package so that you can hook them up directly to a 5V or 12V supply.  But that's just obscuring what's going on.

Check this out for an explanation of what it is exactly that you're doing with that resistor and the LED (read it all, then go back to step 3).  Rather than simply use one of the many web-based automagic calculators, it's better to understand what's actually going on and how that first LED came to be fried!  Also read this at Wikipedia.  It'll tell you about the forward voltages for the different ("miniature") LEDs you're likely to encounter.

Guessing you're in the US?  You could do worse than check out Smallbear for your LEDs.

[deadastronaut]

^ yep...


4.7kohms is 4,700 ohms....   4.7ohms is 4.7...big diiference in resistance/protection....

you can use standard red/yellow/green leds...or clear superbright leds too....with clear superbrights you may want to increase the resistance to 10k-22k ish...

they can get retina destroyingly bright.... ....put your  on..

[Gregmon79]

Thanks guys, I'm making another trip to the shack after work. I know of small bear as well. I've done a few small mods to pedals before with success. Just new to electronics. I always wanted to get more involved and build some pedals of my own. I wanted to start small.

So in saying that the LED I got most likely has a resistor in it, I may not need one then yeah? Maybe..... I'm still going to go order one from small bear too.

[deadastronaut]

radio shack will be fine...

just get a couple to play with...and a couple of 1/4 watt  4.7k resistors...( yellow/purple/red..colour bands on the resistors ok..)


to test your leds..wrap/coil a 4.7 k resistor around the led's 'long leg...

then put the end of that resistor  on 9v +....and the other led leg to - (ground) on a 9v battery...just dont let the legs touch ok.

[PRR]

If the resistor is reasonable for the voltage, and the LED don't light, reverse the LED leads.

If you have built PCs where you have to plug the LEDs to the mobo, you have probably done this.

They are polarity sensitive. If the resistor is reasonable, backward does not kill them, they just do not light.

Yes, getting a 9V battery, several LEDs, several resistors from 1K to 50K, and TRYING it, will teach a lot. Backward don't light. Small resistors pass more current and make more light. Zero resistance lets "infinite" current pass, which will melt either the LED or the battery. (Don't experiment on the good wood table.)