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Hall effect help

Discussion in 'General Electronics Discussion' started by dblD1968, Jun 25, 2014.

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  1. dblD1968


    Jun 11, 2014
    Hi, I am in the middle of an engine conversion and I am stuck...

    I am putting a 2001 engine into a 1988 truck. The last problem I have is I need to figure out how to convert a variable reluctance type sensor reading to a hall affect sensor reading. (DC square wave form from an AC wave form).

    I am using a ECU that is from a 1994 truck so I can have sequential fuel injection. But in order to get that up and running I need the signal from the cam shaft positions sensor to tell my computer when number 1 and number 5 need fuel.

    I recently stumbled upon this.
    To convert the variable reluctance sensor wave form from an AC one to a square DC one.
    "It should be a good starting point. The supply voltageis only +5 volts so it needs to be modified for battery voltage. The LM1815 data sheet shows the maximum supply voltageas +12 volts. For safety I'll add a zener diode to drop the supply voltageto +12. The maximum supply current is 6 mA and typical is 3.6 mA. I'll assume the maximum alternatoroutput/battery voltage is 14 volts. That means a maximum 2volt drop across the resistor at 6 ma or 333 ohms (R=E/I). The standard value is 330 ohms. P=E*I = 2*6 mA = 12 mW. A 1/4 watt resistor is adequate. Pin 5 open selects zero crossing detector Mode 1. The input signal must first cross a 45mV threshold in the positive direction to arm the zero crossing detector, and then cross zero in the negative direction to trigger it. The SOHC VR should generate a signal greater than the threshold. According to the data sheet the signal input voltage at pin 3 is internally clamped. However, it may be prudent to add a small capacitance for noise immunity."

    Does this seem like it will work if I build it?

    If so, I know I need an LM1815 chip. But what else I don't really understand how to decipher the wiring diagram.

    I know very little about building circuits so please explain as if I was 5.
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