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OT: 1N4157 alternative — Parallax Forums

OT: 1N4157 alternative

BasilBasil Posts: 380
edited 2009-07-22 20:40 in Propeller 1
Hi All,

Sorry this is not really a Prop centered question!

Can anyone suggest an alternative to the 1N4157 diode? (Which I could source from RS components)

Thanks [noparse]:)[/noparse]

Alec

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-Alec

Velden in N scale

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-07-21 22:55
    The 1N4157 seems to be a low voltage Zener diode (actually called a Stabistor). There seem to be some that you can find with Google. The National Semiconductor LM385-ADJ is an adjustable voltage reference that can be used in place of a Zener in many circuits. You might look at the datasheet on National Semiconductor's website. There are some more recent similar parts, also in a TO-92 case, on the same website.
  • BasilBasil Posts: 380
    edited 2009-07-21 23:32
    Thanks Mike,

    Is a stabistor a specific type of zener, or simply a name for a zener which meets a set of electrical specs?

    Reason I ask is i'd prefer to use a drop in replacement (i.e. another stabistor) rather than an alternative.

    Thanks for the help!

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    -Alec

    Velden in N scale
  • Bob Lawrence (VE1RLL)Bob Lawrence (VE1RLL) Posts: 1,720
    edited 2009-07-21 23:38
    Basil,

    Re:source from RS components)

    They carry NTE parts but if it's not a stock item they can probably order it for you.


    Replace part.... With NTE part.... Product Line
    1N4157 NTE177 Semiconductor

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    Aka: CosmicBob
  • BasilBasil Posts: 380
    edited 2009-07-21 23:48
    Thanks Bob,

    I must be blind! I can't find NTE177 anywhere on RS's website? :/

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    -Alec

    Velden in N scale
  • BasilBasil Posts: 380
    edited 2009-07-22 00:44
    Would one of these this work?

    docs-asia.electrocomponents.com/webdocs/0733/0900766b8073397e.pdf

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    -Alec

    Velden in N scale

    Post Edited (Basil) : 7/22/2009 12:50:27 AM GMT
  • viskrviskr Posts: 34
    edited 2009-07-22 01:58
    Stabistors are multiple diodes stacked in a single package. The 1N4517 is 3 diodes in series.

    In some transistor amplifiers they were used as a temperature compensator for the transistors, trying to track the Vbe of in this case 3 transistor drops.

    If that's what it's doing, then 3 vanilla diodes in series might be what you need. They are still available from Arrow, but good luck if you need just 1, you might be able to get a sample out of them.

    If its being a voltage reference, there are better options these days.
  • BasilBasil Posts: 380
    edited 2009-07-22 02:36
    Hmmm. I didn't actually design this circuit, i'm just building it [noparse]:)[/noparse]

    This being the case, I haven't got a good understanding of its operations so couldn't tell you what the purpose of the stabistor is.

    The circuit is a DC speed controller for a model railroad.*

    The output from the stabistor is being fed into the THRESHOLD input of a 555. Heres a snippet from the circuit description:
    said...
    The threshold input to the 555 is a voltage dependent on the back EMF of the motor and controls, with the control voltage input, the pulse frequency and period

    I wonder if anyone could suggest the purpose of the stabistor with this info?

    *Note: My plans of prop based DCC controller have been defered due to the cost associated with fitting my already very expensive German loco's with a very expensive DCC decoder :P

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    -Alec

    Velden in N scale
    cab555.png
    1013 x 459 - 23K
  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-07-22 02:54
    From what I can tell, a few diodes in series would work just fine. Looks like a stabistor is basically used as a low voltage Zener, but with a more vertical I-V curve.
  • BasilBasil Posts: 380
    edited 2009-07-22 02:56
    Excellent [noparse]:)[/noparse] I have a ton of both zeners (1n4004) and signal diodes at home [noparse]:)[/noparse] Thanks!

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    -Alec

    Velden in N scale
  • LeonLeon Posts: 7,620
    edited 2009-07-22 13:37
    1N4004 is a rectifier, not a zener!

    Leon

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  • BasilBasil Posts: 380
    edited 2009-07-22 20:40
    You are quite right [noparse]:D[/noparse] I was having a moment...been looking for Zeners all day!

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    -Alec

    Velden in N scale
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