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How do connect a NTE7172 8-Lead DIP with an SCR for a crowbar circuit?

Discussion in 'Radio Circuits, Repair & Performance' started by W6LE, Oct 2, 2011.

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  1. W6LE

    W6LE Ham Member QRZ Page

    I want to make a crowbar circuit to help reduce overvoltage problems on my TS-940. I came across the NTE component "7172 8-Lead DIP", but I can't find clerification on what pins to connect to what part of the circuit. Now I know this is bound to bring some criticism, but I want to use the NTE circuit as opposed to what has been common place. I can't get NTE to cough up any sample diagrams.

    My guess is the Vcc, pin 1, will go to the 28.5 vegulator 'out' and the Vee to ground (this is a positive voltage supply). I believe the Drive Output , pin 8, should be connected to the trip leg of the SCR and the Sense 1 leg, pin 2, to pin 1 of the IC (short pin 2 to pin 1) with the idea that if the regulator out changes more than 2.6 volts, pin 8 will send the drive signal to the SCR and pop the in-line fuse. I thiink there is an internal zenier creating a reference voltage for which the Sense inputs use, or maybe that was a bad dream.
    Anyone willing to put their expertise on the line?
  2. WN6U

    WN6U Subscriber QRZ Page

    Try this link.
  3. W6LE

    W6LE Ham Member QRZ Page

    David ... Thank you for the reference. Fits just right. :cool:

    Jim W.
  4. WN6U

    WN6U Subscriber QRZ Page

    You are welcome.
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