Accelerometer | ADC | ADXL | Adxl20 | AVR | BasicStamp | BX-35 | BX28 | BX35 | COM3 | Compiler | Downloader | EEPROM | Electromagnet | GetADC | GP2D1 | GPS | I2C | IDE | Keypad | LCD | LCD+ | MIDI | Motors | Multitasking | Netmedia | Networking | PCB | PID | PlaySound | PWM | Relays | RTC | Servo | ShiftOut | SitePlayer | SPI | Stack | Timer | USB

Hey,

I want to use some electronic valves to control water flow.
They'd be pretty small valves, just to control small droplets of water.

I'm not really familiar with this kind of thing, so not sure really what terms
to search for, or what I can use.

Hopefully someone here might be able to point me in the right direction,

Thanks,

- Kevin





(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

First,you want valves that are controlled by DC solenoids.

Don't get AC solenoids unless you want to additionally provide relays
to jump from DC to AC .

[UNLESS you need to drive very powerful units or drive some relay
logic, it is actually a big waste as electromagnets work best with DC
and it is really easy to provide a DC power supply from a Wall Wart
OR packaged power supply.]

These solenoids come in different voltages - 5, 12, and 24 are most
common.

Since 12 volt is likly to be most avaiable, I will use it as an
example.

The BX-24 or whatever outputs 5 volts and a limited amount of current
[10mA max per line, but better to use only 1ma per line and run
cooler], so you either have to provide a transistor [a 2n2222] to
handle the switching the additional power and voltage required by the
solenoid or a driver IC.

The UNL2803 is a nice little IC [High-voltage, High-Current
Darlington Arrays] that can control 8 solenoids and easily handle
upto 50 DC volts to supply them. It can also directly connect to the
BX's 5 volt i/o for control as it has TTL, DTl, PMOS, and CMOS
compatible inputs.

It also has transient-protected outputs. That means the solenoids
won't destroy the IC.

So, you have one chip [instead of 8 transistors, 8 resistors or more,
possibly some protection diodes, and a bunch of wire] that will
buffer your BX from the 12 volt world and any solenoid problems.

Of course, you may get 5 volt solenoids and still use the same chip.

Each control line is limited to 500mA. Read the DATA SHEET to find
out what it really can do.

Come to think of it, one IC is probably cheaper that the eight
equivalent transistors.

--- In basicx@basi..., Kevin <p@R...> wrote:
> Hey,
>
> I want to use some electronic valves to control water flow.
> They'd be pretty small valves, just to control small droplets of
water.
>
> I'm not really familiar with this kind of thing, so not sure really
what terms
> to search for, or what I can use.
>
> Hopefully someone here might be able to point me in the right
direction,
>
> Thanks,
>
> - Kevin




(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Hi,

Thanks for that info, it'll be very useful to stop me frying my chip when I
get everything setup! :)

I've been looking for DC solenoid valves, like you suggested, and found this:
http://ie.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=285079&N=0

Is that the kind of thing useful? and/or is their a cheaper alternative.

Eventually I'll need to get quite a lot of these for what I'm trying to do, so
something smaller/lighter would be better if they exist.

Thanks I'm still learning my way around these factsheets,

- Kevin

On Wed, Aug 17, 2005 at 03:26:03PM -0000, G. Kramer Herzog wrote:
> First,you want valves that are controlled by DC solenoids.

> Don't get AC solenoids unless you want to additionally provide relays
> to jump from DC to AC .

> [UNLESS you need to drive very powerful units or drive some relay
> logic, it is actually a big waste as electromagnets work best with DC
> and it is really easy to provide a DC power supply from a Wall Wart
> OR packaged power supply.]

> These solenoids come in different voltages - 5, 12, and 24 are most
> common.

> Since 12 volt is likly to be most avaiable, I will use it as an
> example.

> The BX-24 or whatever outputs 5 volts and a limited amount of current
> [10mA max per line, but better to use only 1ma per line and run
> cooler], so you either have to provide a transistor [a 2n2222] to
> handle the switching the additional power and voltage required by the
> solenoid or a driver IC.

> The UNL2803 is a nice little IC [High-voltage, High-Current
> Darlington Arrays] that can control 8 solenoids and easily handle
> upto 50 DC volts to supply them. It can also directly connect to the
> BX's 5 volt i/o for control as it has TTL, DTl, PMOS, and CMOS
> compatible inputs.

> It also has transient-protected outputs. That means the solenoids
> won't destroy the IC.
>
> So, you have one chip [instead of 8 transistors, 8 resistors or more,
> possibly some protection diodes, and a bunch of wire] that will
> buffer your BX from the 12 volt world and any solenoid problems.
>
> Of course, you may get 5 volt solenoids and still use the same chip.
>
> Each control line is limited to 500mA. Read the DATA SHEET to find
> out what it really can do.
>
> Come to think of it, one IC is probably cheaper that the eight
> equivalent transistors.
>
> --- In basicx@basi..., Kevin <p@R...> wrote:
> > Hey,
> >
> > I want to use some electronic valves to control water flow.
> > They'd be pretty small valves, just to control small droplets of
> water.
> >
> > I'm not really familiar with this kind of thing, so not sure really
> what terms
> > to search for, or what I can use.
> >
> > Hopefully someone here might be able to point me in the right
> direction,
> >
> > Thanks,
> >
> > - Kevin >
> Yahoo! Groups Links



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Kevin,

I don't know the scope of your project, but if you haven't looked at
the NetMedia LCDX module I think you will see a possible all-in-one
solution to driving relays with a BX-24 environment. For $80 you get
a 4x20 LCD display, 8 protected relay drivers, ADC inputs and a nice
integrated package. All of the driving software is available in a
free download as well. It's worth a look to see if it fits your
project.

Dennis --- In basicx@basi..., Kevin <p@R...> wrote:
> Hi,
>
> Thanks for that info, it'll be very useful to stop me frying my
chip
when I
> get everything setup! :)
>
> I've been looking for DC solenoid valves.........





(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Kevin,

I don't know the scope of your project, but if you haven't looked at
the NetMedia LCDX module I think you will see a possible all-in-one
solution to driving relays with a BX-24 environment. For $80 you get
a 4x20 LCD display, 8 protected relay drivers, ADC inputs and a nice
integrated package. All of the driving software is available in a
free download as well. It's worth a look to see if it fits your
project.

Dennis --- In basicx@basi..., Kevin <p@R...> wrote:
> Hi,
>
> Thanks for that info, it'll be very useful to stop me frying my
chip
when I
> get everything setup! :)
>
> I've been looking for DC solenoid valves.........




(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Well....
52 British Pounds is a bit high for solenoid valves, but are these for
a special use? Highly corrosive chemicals, extreme temperature, or
high pressure gas? Why don't they give you their current rating [amps]?

Plain old irrigation solenoid valves in the U.S.A. are about $25USD
each.

And, there are surplus outfits for product oversupply. These can be
cheaper, but you have to accept working with available specifications
rather than fitting to your own.

I am sure you can find something lighter and cheaper. Try your local
yellow pages. You may avoid shipping or locate a salvage dealer.

Since the BasicX is at 5 volts,but can regulate down from a higher
voltage if needed; it would be better to get 9 or 12 volt. The BX-24
wouldn't have to dump so much heat. Alternatively, you could run a
7809 to 'pre-regulate' down to 9 volts and have that regulator dump
most of the heat. Semiconductors suffer most wear from heat.

One of the nice things about the BasicX is that you have a clock on
board for timing on and off cycles in real time.

> I've been looking for DC solenoid valves, like you suggested, and
found this:
> http://ie.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=285079&N=0
>
> Is that the kind of thing useful? and/or is their a cheaper
alternative.
>
> Eventually I'll need to get quite a lot of these for what I'm trying
to do, so
> something smaller/lighter would be better if they exist.
>
> Thanks I'm still learning my way around these factsheets,
>
> - Kevin





(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

On Thu, Aug 18, 2005 at 05:55:10PM -0000, G. Kramer Herzog wrote:
> Well....
> 52 British Pounds is a bit high for solenoid valves, but are these for
> a special use? Highly corrosive chemicals, extreme temperature, or
> high pressure gas? Why don't they give you their current rating [amps]?

Well, 52 euro (about $65) - still not cheap. It's just for water, so I reckon
that one is way overkill for what I need. I probably need the most basic valve
available, it'll only be controlling a very low pressure water supply.

> And, there are surplus outfits for product oversupply. These can be
> cheaper, but you have to accept working with available specifications
> rather than fitting to your own.

> I am sure you can find something lighter and cheaper. Try your local
> yellow pages. You may avoid shipping or locate a salvage dealer.

Sounds like the best plan really! You kind of get into the habit of assuming
everything's cheaper online! :)

> Since the BasicX is at 5 volts,but can regulate down from a higher
> voltage if needed; it would be better to get 9 or 12 volt. The BX-24
> wouldn't have to dump so much heat. Alternatively, you could run a
> 7809 to 'pre-regulate' down to 9 volts and have that regulator dump
> most of the heat. Semiconductors suffer most wear from heat.

> One of the nice things about the BasicX is that you have a clock on
> board for timing on and off cycles in real time.

Thanks for all the help! I've an interesting challenge ahead!

Cheers,

- Kevin





(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

A couple of additional observations.

Solenoid valves vary from a few USD [$2-3) to hundreds. Much depends
on use and expected useful life. All plastic ones seem cheaper.

The $50 range and above have replacement parts to extend their
usefulness.

24volt [maybe AC only] seems to be the standard for industrial and
agricultural applications. I assume it is because the higher voltage
requires less heavy wire for long runs while the 24 volts is much
safer around dampness and soil.

One web site commented that '24volt AC solenoids operate fine on 12
DC'. You may consider that. Obviously, if you have 24 Volt insulation, 12 volts will not break it
down. Additionally, the AC electromagnet has a 'shaded pole' to
achieve function. That 'shaded pole' apparently doesn't matter with
DC. And, the DC duty cycle is 100%, while the AC is 50%.




(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

> ... '24volt AC solenoids operate fine on 12DC'.

My experience is that a shaded-pole 120VAC valve (the washing machine
mixing valves in Photos) can overheat easily on DC voltages.

To silence the hum and buzzing that AC solenoids often emit, I found
that 72VDC was easy to derive from two 24VAC transformers (~36vpk each,
rectified), but the solenoid coil becomes pretty warm pretty quickly.
Higher DC voltages threaten the solenoid, and lower DC voltages are
unreliable. The range between the DC voltage necessary to open such a
valve and that which overheats it is small. I'd expect the same
behavior from 24VAC coils operated on DC. Tom





(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

--- In basicx@basi..., Tom Becker <gtbecker@r...> wrote:
> > ... '24volt AC solenoids operate fine on 12DC'.
>
> My experience is that a shaded-pole 120VAC valve (the washing machine
> mixing valves in Photos) can overheat easily on DC voltages. It seemed too easy, but that's what I read. Sometimes, you can get
away with a lot more as the voltage and amperage go down. After all,
watts usually convert into heat as the means of destruction.

Still from 24 volts down to 12 volts is quite a power reduction. Maybe
you should have run your Washing Machine solenoids at 50 to 60 volts to
avoid the heat buildup.





(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

> Higher DC voltages threaten the solenoid, and lower DC voltages are
> unreliable. The range between the DC voltage necessary to open such
a
> valve and that which overheats it is small. I'd expect the same
> behavior from 24VAC coils operated on DC. > Tom

I misunderstood the above. You are saying that they just NEVER work
right - too hot or not at all.

Thanks




(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

> ... You are saying that they just NEVER work right - too hot or not
at all.

If that is a question, no, I think I said that an 120VAC solenoid will
operate on DC, but that the DC voltage necessary to reliably open the
valves I used was not much below the voltage that overheated the
solenoids. I have not tried this with 24VAC solenoids but I'd expect
similar behavior.

Here are someone's thoughts:
"A solenoid designed to operate on alternating current can also be
operated on direct current. There are, however, some limitations. When
[a] solenoid is powered form DC the current flow is constant regardless
of whether the solenoid is open or closed. The inrush and holding
current are the same. Because of this constant current feature of DC, a
compromise between pull-in force and holding temperature must be made."
http://www.epanorama.net/links/componentinfo.html#solenoids Tom



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Scroll down this pdf to "AC solenoids on DC":
http://www.detroitcoil.com/appdata.pdf
Tom





(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )