Fender Super Twin.

[DrNomis_44]

I did a quick calculation to determine what value resistor I needed to use to limit the current flowing in each led, standard 3 or 5 mm leds can safely run with a maximum of about 20mA flowing through them, any higher than that and you risk destroying the led, and they can actually explode if there's too much current flowing through them, so I deliberately chose to limit the current to about 10mA for each led, the value of the current limiting resistors worked-out to be 330 Ohms, I used three 330 Ohm 1W Metal Film resistors, and they seem to do the job fine, but I'm definitely going to swap the blue led's 330 Ohm current limiting resistor for a higher-value one to tame the brightness, but that's a job for tomorrow.

When a led explodes, it gives-off a very pungent smell, how do I know?, I've had first-hand experience with it.


As a side-note, my pedal board is all up and running again, ready for gigging or recording.

[jugglindan]

I did a quick calculation to determine what value resistor I needed to use to limit the current flowing in each led, standard 3 or 5 mm leds can safely run with a maximum of about 20mA flowing through them, any higher than that and you risk destroying the led, and they can actually explode if there's too much current flowing through them, so I deliberately chose to limit the current to about 10mA for each led, the value of the current limiting resistors worked-out to be 330 Ohms, I used three 330 Ohm 1W Metal Film resistors, and they seem to do the job fine, but I'm definitely going to swap the blue led's 330 Ohm current limiting resistor for a higher-value one to tame the brightness, but that's a job for tomorrow.

When a led explodes, it gives-off a very pungent smell, how do I know?, I've had first-hand experience with it.


As a side-note, my pedal board is all up and running again, ready for gigging or recording.

I think I ended up using 2.4k for the blue LED in the buffer. I normally just put the LED in a breadboard and try resistor values until the brightness looks about right. This is only around 2 or 3mA running off 9v but the brightness looked good.

[DrNomis_44]

I think I ended up using 2.4k for the blue LED in the buffer. I normally just put the LED in a breadboard and try resistor values until the brightness looks about right. This is only around 2 or 3mA running off 9v but the brightness looked good.

I've used a resistor value as high as 47k for a blue led running on a +15V DC supply, and it was still pretty bright,I did a quick calculation and found that a 3k3 resistor will limit the current to 1mA on a +4.8V DC supply for a Blue led, I used 1.5V for the forward-voltage of a Led in my calculation.


I used the following formula to calculate the resistor value:



R=Vs-Vf/I


R= Resistance.

Vs= Supply Voltage.

Vf= Forward-biased Voltage of the Led (typically about 1.5V for standard 3mm and 5mm Leds).

I= Led Forward-Biased Current.


Although, some 3mm and 5mm Blue leds have a Forward-Biased Voltage as high as 3V.