Author Topic: True bypass loop wiring help needed  (Read 383 times)

Guybrush

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True bypass loop wiring help needed
« on: May 16, 2018, 06:31:02 AM »
Hi there

I am planning on building an 8 way TBP loop strip for my baord. I have done some Googling to look for a good wiring diagram but everyone I have found either does mopre than I need (tuner out etc) or is unclear in someway (at least to me). The one I found that seems to best fit the bill for my needs is this one:



The thing I am questioning is the LED wiring. It seems to show the LED taking 9vt from the DC jack with a pull down resistor attached between the negative leg of the LED and the 3pdt. That doesn't sound right to me. Surely the resistor should go between the DC jack and the positive leg of the LED?

Secondly is there a limit to how many LEDs can be powered off 9v? Will each one need to be connected directly to the DC jack in parrallel or can I string them together in series?

Thanks in advance
« Last Edit: May 16, 2018, 06:41:18 AM by Guybrush »

madbean

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Re: True bypass loop wiring help needed
« Reply #1 on: May 16, 2018, 07:36:42 AM »
The purpose of the resistor is to limit the total current flow through the LED and it does so in either position, so yeah that setup works fine.

And, it's not a matter of just 9v being enough to power 8 LEDs....do you have enough current to supply all 8 at once? The answer is yes in both cases for any typical power supply we use for guitar pedals. And, the LEDs must be in parallel.
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Guybrush

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Re: True bypass loop wiring help needed
« Reply #2 on: May 16, 2018, 07:51:11 AM »
Thank you, greatly appreciated.

Just to be clear: The resistor can go on either leg of the LED?

I've always assumed that it needs to go inbetween the 9v supply and the positive leg to limit the current before it hits the LED.


JackSkellington

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Re: True bypass loop wiring help needed
« Reply #3 on: May 16, 2018, 08:05:42 AM »
I've always assumed that it needs to go inbetween the 9v supply and the positive leg to limit the current before it hits the LED.

Exactly what I've always thought! :o
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Guybrush

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Re: True bypass loop wiring help needed
« Reply #4 on: May 16, 2018, 12:24:32 PM »
I've just tested it and what Madbean/Brian said above is (of course) correct. The resistor can attach to any leg of the LED.

Every day is a school day.

Cheers Brian!