School me on using electric "bucks" to control voltage?

toximus

toximus

My Jeep ♥️ me
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Aftermarket engine swap stuff here...

I had an idea to double up the inputs on my LS swapped dash. The dash analog input can sense voltage which I can use to turn on indicator lights.

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I'm thinking about using something like this: https://www.adafruit.com/product/4739 or this: https://www.adafruit.com/product/1385

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I only have the +12v indicator leads from the OEM TJ cluster connectors, so how would I practically wire this up? I'm hoping to learn something new!
 
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The headlights seem like a give me since I can safely assume the headlights are on since they must be on in order to have brights. However, is there an easy way to combine inputs that can be on at the same time? For example: Left turn signal = 5v, right turn signal = 12v, combined (warning flashers) they equal something else?
 
toximus said:
The headlights seem like a give me since I can safely assume the headlights are on since they must be on in order to have brights. However, is there an easy way to combine inputs that can be on at the same time? For example: Left turn signal = 5v, right turn signal = 12v, combined (warning flashers) they equal something else?
Click to expand...

I have doubled up some inputs on vintage dashes. 47 woodie for example I tied the high beam indicator, I tied both turn signals circuits into the ground side with a diode on each wire to prevent side to side feedback. The indicator would turn on with high beams on and flash with turn signals on
 
For my AEM they offer input expansion devices that connect into the canbus however I’m leaning towards not integrating things into the dash if I don’t need to and wiring up some LED’s instead.

They have pretty much everything you would want. High beams, 4X4, Lockers etc.

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Apparition said:
For my AEM they offer input expansion devices that connect into the canbus however I’m leaning towards not integrating things into the dash if I don’t need to and wiring up some LED’s instead.

They have pretty much everything you would want. High beams, 4X4, Lockers etc.

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Click to expand...

I've got a fun collection of those too but I ultimately want to run everything through the dash. I have 8 inputs, which is enough, but if I can combine them now it'll leave some available.
 
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Is my very limited knowledge of resistors (which I just learned this week lol) correct? It might actually be closer to 6v but that's okay with me.

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toximus said:
Is my very limited knowledge of resistors (which I just learned this week lol) correct? It might actually be closer to 6v but that's okay with me.

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Click to expand...

Yes, your use of a voltage divider is correct. However, keep in mind that the operating voltage varies with load on the battery. Depending on how the dash uses the input voltage, you need to be sure the trigger works for all operating voltages (typically about 11V to about 15V). In addition, resistors come in different tolerances, usually from 1% to 10%, indicated by one of the band colors, and the actual resistance will affect that signal voltage. “Standard” resistors are typically of the 10% tolerance type, and if one is 10% high and the other 10% low, the voltage divider will be either 45% or 55% instead of 50%.
 
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