LM1815 input conditioning?

Discussion in 'General Electronics Chat' started by geekoftheweek, Sep 13, 2015.

  1. geekoftheweek

    Thread Starter Member

    Oct 6, 2013
    42
    2
    I am looking to use a LM1815 (http://www.mouser.com/ds/2/405/lm1815-443409.pdf) in a project. I'm wanting to know what kind of modifications may be needed to the circuit on page 6 to work with my sensor or is that pretty much a circuit that works with anything? I have no idea of the specs of the vr sensor I'm using other than when it rotates the way it's designed it will cross to negative when the tab passes the sensor. I've read that by spinning the assembly by hand that it should put out around 1.5 volts and at full speed may be over 50 volts. What would be the proper way to limit the input voltage?
     
    Last edited: Sep 13, 2015
  2. geekoftheweek

    Thread Starter Member

    Oct 6, 2013
    42
    2
    So I've done what I should have done in the first place... read the datasheet The way it looks to me the 18k resistor on pin 3 would allow for a 54 volt input (at 3mA). How about a tvs or a pair of zeners to eliminate anything over say 48 volts just in case? What effect if any would a bigger resistor have on the chip? I was thinking of at least 34k which would give me a 100 volt range.

    I'm thinking the tvs or zeners actually would suit my situation better as it would limit the input voltage instead of trying to allow for an unknown. How's that idea sound?
     
    Last edited: Sep 13, 2015
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