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Two Questions.... — Parallax Forums

Two Questions....

ArchiverArchiver Posts: 46,084
edited 2001-04-02 23:24 in General Discussion
Hello All,

········I've beenaway from electronics for a while and would appreciate current partnumber recommendations for the latest Stamp project.··· Ineed a basic comparator I.C. and a ???FET transistor for the output ofthe comparator to drive on and off.· The load that the transistor isswitching is light at only 250mA and it's non-inductive -- my onlyrequirement is a low "on" resistance.· Are the 741 op-ampand 339 comparator parts still in use?· What are all of you usingfor a basic comparator and a general purpose FET transistor?

Thank You,
Tim

Timothy Medema
CrystaLite, Inc.
3307 CedarSt.··················(425)745-6000·· 800-666-6065
Everett, WA98201···············Fax[noparse]:([/noparse]425) 257-0232

www.crystaliteinc.com···········timm@crystaliteinc.com


The information transmitted is intended onlyfor the person or entity to whom it is addressed and may containconfidential and/or privileged material.· Any review,retransmission, dissemination or other use of, or taking of any action inreliance upon, this information by persons or entities other than theintended recipient is prohibited.· If you received this in error,please contact the sender and delete the material from anycomputer.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-03-30 20:18
    The 741 and 339 are still available and cheap ... I still use them. For
    MOSFETS, check out http://www.digikey.com

    If you look in their catalog, page 288, for example, they list an IRLD024-ND
    for $1.26 ea. It operates from logic-level drive, has 0.1 ohm
    on-resistance, has a VDS rating of 60V, and comes in a 4 pin DIP. They list
    many other devices, as well.

    Ray McArthur

    > I've been away from electronics for a while and would appreciate
    > current part number recommendations for the latest Stamp project. I
    need
    > a basic comparator I.C. and a ???FET transistor for the output of the
    > comparator to drive on and off. The load that the transistor is switching
    > is light at only 250mA and it's non-inductive -- my only requirement is a
    > low "on" resistance. Are the 741 op-amp and 339 comparator parts still in
    > use? What are all of you using for a basic comparator and a general
    > purpose FET transistor?
  • ArchiverArchiver Posts: 46,084
    edited 2001-03-30 21:30
    Thank you Ray,

    ········I have notused MOSFETS before, can you (or any of you) point me in the direction ofa summary or a tutorial on how to use them?

    Thanks again,
    Tim

    At 02:18 PM 3/30/2001 -0500, you wrote:
    The 741 and 339 are still availableand cheap ... I still use them.· For
    MOSFETS, check outhttp://www.digikey.com

    If you look in their catalog, page 288, for example, they list anIRLD024-ND
    for $1.26 ea.· It operates from logic-level drive, has 0.1 ohm
    on-resistance, has a VDS rating of 60V, and comes in a 4 pin DIP.·They list
    many other devices, as well.

    Ray McArthur

    >········· I've been awayfrom electronics for a while and would appreciate
    > current part number recommendations for the latest Stampproject.··· I
    need
    > a basic comparator I.C. and a ???FET transistor for the output ofthe
    > comparator to drive on and off.· The load that the transistoris switching
    > is light at only 250mA and it's non-inductive -- my only requirementis a
    > low "on" resistance.· Are the 741 op-amp and 339comparator parts still in
    > use?· What are all of you using for a basic comparator and ageneral
    > purpose FET transistor?





    Your use of Yahoo! Groups is subject tohttp://docs.yahoo.com/info/terms/

    Timothy Medema
    CrystaLite, Inc.
    3307 Cedar St.··················(425) 745-6000·· 800-666-6065
    Everett, WA 98201···············Fax: (425) 257-0232

    www.crystaliteinc.com···········timm@crystaliteinc.com


    The information transmitted is intended only for the person or entity to whom it is addressed and may contain confidential and/or privileged material.· Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.· If you received this in error, please contact the sender and delete the material from any computer.
  • ArchiverArchiver Posts: 46,084
    edited 2001-03-30 23:19
    Hi Tim,
    Usually you want an N-channel device. A typical circuit would be to connect
    the source to gnd, the gate to logic level through ~1K, and the drain to the
    load. The other load connects to positive power. The input impedance to the
    gate is many megohms shunted by hundreds to thousands of pf, depending on
    device size. The gate is sensitive to ESD, so use care in handling. There
    is an introduction at

    http://www.americanmicrosemi.com/tutorials/mosfets.htm

    Ray McArthur
    Original Message
    From: Timothy Medema <timm@c...>
    To: <basicstamps@yahoogroups.com>
    Sent: Friday, March 30, 2001 3:30 PM
    Subject: Re: [noparse][[/noparse]basicstamps] Two Questions....


    >
    > Thank you Ray,
    >
    > I have not used MOSFETS before, can you (or any of you) point me
    > in the direction of a summary or a tutorial on how to use them?
  • ArchiverArchiver Posts: 46,084
    edited 2001-04-02 22:10
    ········Manythanks to Ray and David for up to date part recommendations.· Anyoneelse have suggestions for basic single supply voltage comparator andop-amp or a MOSFET transistor that will turn completely on with a +5 VDCdrive signal?

    Tim


    Timothy Medema
    CrystaLite, Inc.
    3307 CedarSt.··················(425)745-6000·· 800-666-6065
    Everett, WA98201···············Fax[noparse]:([/noparse]425) 257-0232

    www.crystaliteinc.com···········timm@crystaliteinc.com


    The information transmitted is intended onlyfor the person or entity to whom it is addressed and may containconfidential and/or privileged material.· Any review,retransmission, dissemination or other use of, or taking of any action inreliance upon, this information by persons or entities other than theintended recipient is prohibited.· If you received this in error,please contact the sender and delete the material from anycomputer.
  • ArchiverArchiver Posts: 46,084
    edited 2001-04-02 23:24
    Hi David,

    ········I'velooked up the LM324 and it's being shown as a general purposeop-amp.· Are you configuring it as a comparator or do I have thepart number wrong perhaps?· Any insight is much appreciated.

    Tim


    Timothy Medema
    CrystaLite, Inc.
    3307 CedarSt.··················(425)745-6000·· 800-666-6065
    Everett, WA98201···············Fax[noparse]:([/noparse]425) 257-0232

    www.crystaliteinc.com···········timm@crystaliteinc.com


    The information transmitted is intended onlyfor the person or entity to whom it is addressed and may containconfidential and/or privileged material.· Any review,retransmission, dissemination or other use of, or taking of any action inreliance upon, this information by persons or entities other than theintended recipient is prohibited.· If you received this in error,please contact the sender and delete the material from anycomputer.
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