What value resistor do I need?

Frequently asked question regarding resistors, potentiometers, types, requirements, ratings etc.

What value resistor do I need?

Postby guitarplayer08 » 03 Feb 2013, 03:02

Hi all,

This is my first time here and I am a total beginner when it comes to electronics. I am building a true bypass looper with 6 loops & 1 master bypass switch following this schematic: http://i2.photobucket.com/albums/y50/PR ... oop-MB.png. However, the schematic is only for 4 loops & 1 master bypass. My question is, beside adding more switches and jacks, what do I have to do to the 4.7K resistors value?

Also, in the above diagram will electric current flow from the red cable from the DC jack going through the series of LEDs (positive legs) then to the resistors and finally into the switches?

Thanks again
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Re: What value resistor do I need?

Postby Lucifer » 03 Feb 2013, 12:32

The 4.7k resistors are there to limit the current through each LED. It's a nominal value, for a nominal, regular type of LED. but it should work whatever LEDs you use. It does not depend on how many LEDs there are, as each LED has its own resistor.

You may want to reduce the value of the resistors to make the LEDs brighter, or increase the value to make the LEDs less bright. And if you used different coloured LEDs for each channel, you will probably need different resistor values for each one, in order to get the same brightnesses. But start with 4.7k resistors and see how you go.

Yes, current flows (in the conventional sense, from positive to negative) from the positive input, through a LED and its resistor then to the switch, where it can then flow to ground when the switch is activated.

To expand the unit, just add more of the same - switches, jacks, LEDs and resistors.

Good luck :thumbsup
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