LED *on the blink*

[anonymous]

Built the Runt. Sounds great. First build ever (still unboxed). Had a blast. BUT...

I originally used a 3mm blue LED for a power indicator. I noticed when I touched one of the LED leads when it was powered, it glowed slightly, although the pedal was off. I then turned the pedal on, and after a minute or two of playing through it the LED apparently died. I replaced it with 3mm green. It began blinking when I turned it on and played, and died very quickly.

I am using a CA3130EZ instead of the LM308. Also, I am using an electrolytic capacitor for C9, however the polarity is correct.

Any idea what's frying my LEDs? This was really fun for me and I'm eager to get it into a box!

[Thomas_H]

Did you use a resistor in series with the LED?
Which value ?

[anonymous]

Yes I did. I see now that I used a 47 Ohm resistor instead of 47k... Thanks for the quick reply. I'll make sure to keep my values straight next time! Have you built this pedal? It sounds great through both my bass and guitar, when I play through a Bass VI there's a terrible hiss and it seems like there is some sort of phasing going on. Ever experience that with this pedal?

[Thomas_H]

47k might be a little to much   - try 1k so it does not burn the LED or 20k if it is a ultrabright type.

I did not build the Runt but its just a Rat.
There should be no hiss or phasing. Maybe because its still unboxed -?

If you use it for bass you might want to change the input capacitor to 220n or so.

[davent]

I've had some green Ultrabrights that needed that 47k but usually ~20k is close enough. I'l power up each led through a resistor switch box before finalizing the CLR for a build, many different LED's from many diffferent sources, different colours, shapes and sizes and they all want something different for the CLR, from 500Ω to 47k.

dave

[anonymous]

If you use it for bass you might want to change the input capacitor to 220n or so.

Could you explain why, exactly, that is? I put 2 100n caps in series in C1 since I did not have a 220n, and do not notice much difference. What is the added capacitance doing?

[jimilee]

Added frequency, if you build it to guitar specs you will likely lose the bottom end when you turn it on. I would socket the cap and experiment.

[jimilee]

I've had some green Ultrabrights that needed that 47k but usually ~20k is close enough. I'l power up each led through a resistor switch box before finalizing the CLR for a build, many different LED's from many diffferent sources, different colours, shapes and sizes and they all want something different for the CLR, from 500Ω to 47k.

dave

Here's an interesting piece of information, the 3 mm clear led turns orange right before it burns out! Ask me how I know...

[anonymous]

Cool, I ended up with 200n on the input cap and 2u2 on the output and it sounds to my liking. A noticeable amount of bass increase. WOO BOY this is fun stuff!

JL

[jimilee]

Great to hear it.

[culturejam]

I was expecting a 555 timer blinking LED circuit question.