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PTC thermistor

Discussion in 'Electronic Design' started by Lowly Engineer, Feb 23, 2004.

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  1. I'm building an airflow sensor, and I only have 5V at 100mA available.
    Although I could use a heated wire, they can be fragile and difficult
    to deal with. What I would really like is a tiny PTC thermistor that
    has a 25C resistance of 100 ohms or less.

    My goal is to have it self-heat a significant amount when 5V is
    applied. 25C above ambient would be enough. (Ambients up
    to 60C)

    Also, a bead shape (rather than disk) is preferred, so it will react
    uniformly to airflow from any direction.

    All the PTC thermistors I have found are either too large, therefore
    they won't self-heat enough with 5V 100mA or the resistance is so high
    they won't heat up with 5V or they are disk types and therefore
    airflow direction is very critical.

    Does anyone know who makes a device that might work for me?
  2. Take a look at:

    they are available from Digi-Key.

    Don Cleveland
  3. CBarn24050

    CBarn24050 Guest

    Hi. lots of people use a NTC thermistor, there are loads of small ones around.
    Many years ago I made an airflow sensor with a pt100 probe.
  4. Ian Stirling

    Ian Stirling Guest

    3V zener diode, with axial leads?

    Do you want to sense accurately, or are you just looking for a threshold?
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