What voltage divider do I buy ?

[Joe-405]

I need to go from 12 volts to 1. I need to bypass my tip sensor so the engine will start. I can’t figure out which one to get.

And also does it matter which way the 100ohm 1/2 watt resistor is soldered in the grey wire ?

And here is what I’m referring to from another forum I accidentally came across on another guy building a stand alone with a oem harness and ecu.............

 

[Functional Artist]

Here is some info I dug up while working on another project

Hope it helps

Voltage Divider

In electronics, a voltage divider (also known as a potential divider) is a passive linear circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). Voltage division is the result of distributing the input voltage among the components of the divider. A simple example of a voltage divider is two resistors connected in series, with the input voltage applied across the resistor pair and the output voltage emerging from the connection between them.

Resistor voltage dividers are commonly used to create reference voltages, or to reduce the magnitude of a voltage so it can be measured, and may also be used as signal attenuators at low frequencies. For direct current and relatively low frequencies, a voltage divider may be sufficiently accurate if made only of resistors; where frequency response over a wide range is required (such as in an oscilloscope probe), a voltage divider may have capacitive elements added to compensate load capacitance. In electric power transmission, a capacitive voltage divider is used for measurement of high voltage.


This site has some kool info

...& even a Voltage Divider calculator, that you can plug in numbers for (Vin) & both resistors & see what kind of out put voltage they produce (Vout)

https://learn.sparkfun.com/tutorials/voltage-dividers


* Voltage Dividers should not be used to supply power to a load

As tempting as it may be to use a voltage divider to step down, say, a 12V power supply to 5V, voltage dividers should not be used to supply power to a load.

Any current that the load requires is also going to have to run through R1. The current and voltage across R1 produce power, which is dissipated in the form of heat. If that power exceeds the rating of the resistor (usually between ⅛W and 1W), the heat begins to become a major problem, potentially melting the poor resistor.

That doesn’t even mention how inefficient a voltage-divider-power-supply would be. Basically, don’t use a voltage divider as a voltage supply for anything that requires even a modest amount of power. If you need to drop down a voltage to use it as a power supply, look into voltage regulators or switching supplies.

 

[TT540]

Pretty simple to implement.

1) The resistor does not have direction, so it can go in either way. Just zip tie it off so the leads do not vibrate and break.

2) for the sensor that you need to duplicate using a voltage divider, the two resistor trick is a typical approach. Most sensors are just resistors in fancy packages that changes their resistance based on some mechanical input like pressure, temperature, throttle movement...
So you want to go from 12 down to 1 volt.

Best to stick with resistors above 1k ohms.
Here is a link to a voltage divider calculator:

http://www.ohmslawcalculator.com/voltage-divider-calculator

Choose 1100 ohms for R1
Choose 100 ohms for R2

1100 ohms = 1.5 Kohms when shopping.
1/2 way resistors are good to use.

This way you can reuse the same resistors for that gray wire in #1 above