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Boost the voltage of an output

ArchiverArchiver Posts: 46,084
edited 2003-08-18 14:05 in General Discussion
Hey All,

Forgive me if this question is off-topic, but it does involve a basic
stamp.

I want to control the communications between 2 devices using a basic
stamp to manage the communications. The basic stamp is connected to
both devices and both devices are connected to each other over a single
pin.

The problem is the 2 devices disagree on what High is.

1 device high state is about 2.7 volts and low of about 1.7 and the
device I want to talk to is looking for a high input of about 3.5 volts
and a low about 1.4.

I have been reading around and I think this can be solved a few ways

1. connect 2 logic gates in parallel which will almost double my
output voltage then pull it back a little with a resistor.

2. get a power mosfet that meets my specifications.

3. use a silicon controlled rectifier.

I'm very inexperienced do these options make sense?

Any recommendations?

Thanks,

Ben

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-08-16 14:00
    Connecting 3-terminal regulators in parallel may seems to work.
    However the reality is than each regulator output is set by its
    internal reference. with regulators in parallel the device with the
    higher output setting will provide all the current because the other
    regulator will shut off. Even a few millivolts of difference in the
    output of the regulator is enough to shut off the regualtor with
    lower output voltage.
  • ArchiverArchiver Posts: 46,084
    edited 2003-08-16 14:53
    In a message dated 8/16/2003 4:24:41 AM Pacific Daylight Time, ben@c...
    writes:

    > Hey All,
    >
    > Forgive me if this question is off-topic, but it does involve a basic
    > stamp.
    >
    > I want to control the communications between 2 devices using a basic
    > stamp to manage the communications. The basic stamp is connected to
    > both devices and both devices are connected to each other over a single
    > pin.
    >
    > The problem is the 2 devices disagree on what High is.
    >
    > 1 device high state is about 2.7 volts and low of about 1.7 and the
    > device I want to talk to is looking for a high input of about 3.5 volts
    > and a low about 1.4.
    >
    > I have been reading around and I think this can be solved a few ways
    >
    > 1. connect 2 logic gates in parallel which will almost double my
    > output voltage then pull it back a little with a resistor.
    >
    > 2. get a power mosfet that meets my specifications.
    >
    > 3. use a silicon controlled rectifier.
    >
    > I'm very inexperienced do these options make sense?
    >
    > Any recommendations?
    >
    > Thanks,
    >
    > Ben

    Ben,

    For the device that recognizes high as 2.7 volts, what is the supply voltage
    to this device, is it 5 volts?

    For the device that recognizes high as 3.5 volts, what is the supply voltage
    to this device, is it also 5 volts?

    If both devices are not powered by 5 volts, what is the supply power to each
    device. The answer to these questions will be needed to give you a solution.


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-08-16 15:46
    On Saturday, August 16, 2003, at 09:53 AM, smartdim@a... wrote:

    > For the device that recognizes high as 2.7 volts, what is the supply
    > voltage
    > to this device, is it 5 volts?

    No the power source is 2 AA batteries I observed to be around 2.7
    volts.

    >
    > For the device that recognizes high as 3.5 volts, what is the supply
    > voltage
    > to this device, is it also 5 volts?

    Yes this power supply is 5 volts

    >
    > If both devices are not powered by 5 volts, what is the supply power
    > to each
    > device. The answer to these questions will be needed to give you a
    > solution.

    Thanks for your interest.

    Ben
  • ArchiverArchiver Posts: 46,084
    edited 2003-08-16 16:20
    In a message dated 8/16/2003 7:47:19 AM Pacific Daylight Time, ben@c...
    writes:

    > >For the device that recognizes high as 2.7 volts, what is the supply
    > >voltage
    > >to this device, is it 5 volts?
    >
    > No the power source is 2 AA batteries I observed to be around 2.7
    > volts.
    >
    > >
    > >For the device that recognizes high as 3.5 volts, what is the supply
    > >voltage
    > >to this device, is it also 5 volts?
    >
    > Yes this power supply is 5 volts
    >
    > >
    > >If both devices are not powered by 5 volts, what is the supply power
    > >to each
    > >device. The answer to these questions will be needed to give you a
    > >solution.
    >
    > Thanks for your interest.
    >
    > Ben
    >

    Ben,

    One simple and reliable solution (at the expense of pin and hardware) is to
    use opto isolators, like a 4N35. Also, there will be inversion with the logic
    level, but this can easily be dealt with with the software. Or, an additional
    transistor will eliminate inversion......
    <A
    HREF="http://www.fairchildsemi.com/ds/4N/4N35.pdf">http://www.fairchildsemi.com/\
    ds/4N/4N35.pdf
    </A>

    If you are unclear on how to use the device, you can send me your phone
    number directly to my email address and I could call you. Trying to explain in
    writing is possible, but cumbersome.


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-08-18 13:14
    use an optical isolator between the two devices and then you can shift the
    voltages as you like and protect both.
    Jim
    http://www.geocities.com/jimforkin2003/


    Original Message
    From: smartdim@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=JC3qzbYz9lAqkxS0jahHLDySuaDpKbnopzhHOCxqY9aP3QRbFLhWmeBWg4wbEBpruNB6kdFVMSQ]smartdim@a...[/url
    Sent: Saturday, August 16, 2003 9:53 AM
    To: basicstamps@yahoogroups.com
    Subject: Re: [noparse][[/noparse]basicstamps] Boost the voltage of an output


    In a message dated 8/16/2003 4:24:41 AM Pacific Daylight Time, ben@c...
    writes:

    > Hey All,
    >
    > Forgive me if this question is off-topic, but it does involve a basic
    > stamp.
    >
    > I want to control the communications between 2 devices using a basic
    > stamp to manage the communications. The basic stamp is connected to
    > both devices and both devices are connected to each other over a single
    > pin.
    >
    > The problem is the 2 devices disagree on what High is.
    >
    > 1 device high state is about 2.7 volts and low of about 1.7 and the
    > device I want to talk to is looking for a high input of about 3.5 volts
    > and a low about 1.4.
    >
    > I have been reading around and I think this can be solved a few ways
    >
    > 1. connect 2 logic gates in parallel which will almost double my
    > output voltage then pull it back a little with a resistor.
    >
    > 2. get a power mosfet that meets my specifications.
    >
    > 3. use a silicon controlled rectifier.
    >
    > I'm very inexperienced do these options make sense?
    >
    > Any recommendations?
    >
    > Thanks,
    >
    > Ben

    Ben,

    For the device that recognizes high as 2.7 volts, what is the supply voltage
    to this device, is it 5 volts?

    For the device that recognizes high as 3.5 volts, what is the supply voltage
    to this device, is it also 5 volts?

    If both devices are not powered by 5 volts, what is the supply power to each
    device. The answer to these questions will be needed to give you a solution.


    [noparse][[/noparse]Non-text portions of this message have been removed]


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  • ArchiverArchiver Posts: 46,084
    edited 2003-08-18 13:17
    Don't connect three terminal regulators in parallel. Use one to regulate
    the base voltage on a pass transistor instead and then you can pass the
    higher current up to the capabilities of the pass transistor.

    jim
    http://www.geocities.com/jimforkin2003/


    Original Message
    From: Albert Catano [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=VXhOIZETECg-Nhvvy3Jo_geKyf6Xgm4IrfhnlNTJitzAXUhCMW1ZhPbFYgp4eSfMaMefifOwp5loKUinGzQ]acatano2002@y...[/url
    Sent: Saturday, August 16, 2003 9:00 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Boost the voltage of an output


    Connecting 3-terminal regulators in parallel may seems to work.
    However the reality is than each regulator output is set by its
    internal reference. with regulators in parallel the device with the
    higher output setting will provide all the current because the other
    regulator will shut off. Even a few millivolts of difference in the
    output of the regulator is enough to shut off the regualtor with
    lower output voltage.




    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
    from the same email address that you subscribed. Text in the Subject and
    Body of the message will be ignored.


    Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
  • ArchiverArchiver Posts: 46,084
    edited 2003-08-18 14:05
    This solution will ok except you lose the current limit and short
    circuit protection.
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