Variable voltage
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Hey group!
I don't know how to accomplish this, so I thought I would ask for
your assistance. I need to be able to send a command from the Stamp
that will somehow convert to a voltage used to run the voltage control
on a 555 timer chip (to vary the frequency). However, I have to only
just output a command for a brief time as the stamp will be performing
other routines, but I need the voltage to stay on all the time. The
voltage value will only be changing every second, but will be
constantly happening as opposed to a one time event, so I need
something reliable that won't readily wear out. Let me know your
thoughts. Thanks!
I don't know how to accomplish this, so I thought I would ask for
your assistance. I need to be able to send a command from the Stamp
that will somehow convert to a voltage used to run the voltage control
on a 555 timer chip (to vary the frequency). However, I have to only
just output a command for a brief time as the stamp will be performing
other routines, but I need the voltage to stay on all the time. The
voltage value will only be changing every second, but will be
constantly happening as opposed to a one time event, so I need
something reliable that won't readily wear out. Let me know your
thoughts. Thanks!
Comments
>Hey group!
>
> I don't know how to accomplish this, so I thought I would ask for
>your assistance. I need to be able to send a command from the Stamp
>that will somehow convert to a voltage used to run the voltage control
>on a 555 timer chip (to vary the frequency). However, I have to only
>just output a command for a brief time as the stamp will be performing
>other routines, but I need the voltage to stay on all the time. The
>voltage value will only be changing every second, but will be
>constantly happening as opposed to a one time event, so I need
>something reliable that won't readily wear out. Let me know your
>thoughts. Thanks!
>
>Look at digital potentiometers,
>
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of the message will be ignored.
>
>Yahoo! Groups Links
>
>
>
>
I just figured out how to use a digital pot the other day. Very handy and
will do what you want. I have a code snip for the MCP41050, and it should
work with any of the Microchip pots. Dallas/Maxim also makes pots that are
just as easy to use.
Jonathan
www.madlabs.info
Original Message
From: "David M Kissick" <geckoinc99@y...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, February 20, 2004 1:25 PM
Subject: [noparse][[/noparse]basicstamps] Variable voltage
> Hey group!
>
> I don't know how to accomplish this, so I thought I would ask for
> your assistance. I need to be able to send a command from the Stamp
> that will somehow convert to a voltage used to run the voltage control
> on a 555 timer chip (to vary the frequency). However, I have to only
> just output a command for a brief time as the stamp will be performing
> other routines, but I need the voltage to stay on all the time. The
> voltage value will only be changing every second, but will be
> constantly happening as opposed to a one time event, so I need
> something reliable that won't readily wear out. Let me know your
> thoughts. Thanks!
>
>
>
> 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.
>
> Yahoo! Groups Links
>
>
>
>
>
>
handy and
> will do what you want. I have a code snip for the MCP41050, and it
should
> work with any of the Microchip pots. Dallas/Maxim also makes pots
that are
> just as easy to use.
>
> Jonathan
Hey there!
Thanks for the reply. I wasn't sure if a digital pot would wear
down over time or how well it would work having to change so often,
but everyone seems to feel that it would do well. The basic code for
using one would be very much appreciated. Also, what's your opinion
on how well these things last. As I said, it will be switching quite
often, but in small increments. What's happening is that this is part
of a variometer project I've been working on for quite some time now.
It's an instrument used for hang gliding to tell us if we're in lift
and how fast we're going up. Most have an audio option so that you're
looking at where you're going and not at the screen. the frequency
and beep rate get higher and faster as you get faster. The variometry
is being calculated in the Stamp, so I needed some way to put out a
varying voltage to control a 555 timer to change the frequency and
beep rate. This will also explain why I need something that will last
because of the constant use. Anyway, that's what I'm looking at. If
you feel a digital pot will handle this, then great. Thanks again for
the help.
David
I can't say how long they will last. I am just using my first one in a
circuit I am working on. I can say that they are fast and accurate so far.
Here is a code snip for a MCP41XXX:
cs con 0
clk con 1
si con 2
potData var word
potSet var potData.lowbyte
potData = %00010000100000000
main:
pause 100
debug "PotSet: ", dec potSet,cr
low CS
shiftout si,sck,msbfirst,[noparse][[/noparse]potData\16]
high cs
if potSet = 255 then
potset = 0
goto main
endif
potSet = potSet +1
goto main
That should get you up and going. You can get a free sample or two from
microchip, just go to their website.
Jonathan
www.madlabs.info
Original Message
From: "David M Kissick" <geckoinc99@y...>
To: <basicstamps@yahoogroups.com>
Sent: Saturday, February 21, 2004 6:11 AM
Subject: [noparse][[/noparse]basicstamps] Re: Variable voltage
> > I just figured out how to use a digital pot the other day. Very
> handy and
> > will do what you want. I have a code snip for the MCP41050, and it
> should
> > work with any of the Microchip pots. Dallas/Maxim also makes pots
> that are
> > just as easy to use.
> >
> > Jonathan
>
> Hey there!
> Thanks for the reply. I wasn't sure if a digital pot would wear
> down over time or how well it would work having to change so often,
> but everyone seems to feel that it would do well. The basic code for
> using one would be very much appreciated. Also, what's your opinion
> on how well these things last. As I said, it will be switching quite
> often, but in small increments. What's happening is that this is part
> of a variometer project I've been working on for quite some time now.
> It's an instrument used for hang gliding to tell us if we're in lift
> and how fast we're going up. Most have an audio option so that you're
> looking at where you're going and not at the screen. the frequency
> and beep rate get higher and faster as you get faster. The variometry
> is being calculated in the Stamp, so I needed some way to put out a
> varying voltage to control a 555 timer to change the frequency and
> beep rate. This will also explain why I need something that will last
> because of the constant use. Anyway, that's what I'm looking at. If
> you feel a digital pot will handle this, then great. Thanks again for
> the help.
>
> David
>
>
>
> 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.
>
> Yahoo! Groups Links
>
>
>
>
>
>
simple stepper motor drive. The circuit works very well for small steps.
There are no moving parts in a digital pot to wear out. I have some units that
are
5 years old and still working fine.
I use the Analog Devices AD7376, but the Microchip units are just as good.
Good Luck,
Alan Bradford
Plasma Technologies
In a message dated 2/21/04 9:13:28 AM Eastern Standard Time,
geckoinc99@y... writes:
> I just figured out how to use a digital pot the other day. Very
handy and
> will do what you want. I have a code snip for the MCP41050, and it
should
> work with any of the Microchip pots. Dallas/Maxim also makes pots
that are
> just as easy to use.
>
> Jonathan
Hey there!
Thanks for the reply. I wasn't sure if a digital pot would wear
down over time or how well it would work having to change so often,
but everyone seems to feel that it would do well. The basic code for
using one would be very much appreciated. Also, what's your opinion
on how well these things last. As I said, it will be switching quite
often, but in small increments. What's happening is that this is part
of a variometer project I've been working on for quite some time now.
It's an instrument used for hang gliding to tell us if we're in lift
and how fast we're going up. Most have an audio option so that you're
looking at where you're going and not at the screen. the frequency
and beep rate get higher and faster as you get faster. The variometry
is being calculated in the Stamp, so I needed some way to put out a
varying voltage to control a 555 timer to change the frequency and
beep rate. This will also explain why I need something that will last
because of the constant use. Anyway, that's what I'm looking at. If
you feel a digital pot will handle this, then great. Thanks again for
the help.
David
[noparse][[/noparse]Non-text portions of this message have been removed]
>of a variometer project I've been working on for quite some time now.
> It's an instrument used for hang gliding to tell us if we're in lift
>and how fast we're going up. Most have an audio option so that you're
>looking at where you're going and not at the screen. the frequency
>and beep rate get higher and faster as you get faster. The variometry
>is being calculated in the Stamp, so I needed some way to put out a
>varying voltage to control a 555 timer to change the frequency and
>beep rate. This will also explain why I need something that will last
>because of the constant use.
Another state of the art option would be a direct digitally
controlled oscillator like the
Linear Tech LTC6904 ($3).
http://www.linear.com/prod/datasheet.html?datasheet=1067
The frequency range of this one 8-pin chip is 1khz to 68mhz--right, 1
kilohertz to 68 megahertz--I2C or SPI input and complementary clock
outputs. Four control bits set the octave (1 to 2 khz, 2 to 4 khz,
etc) and then the resolution over that octave is 10 bits.
-- Tracy