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555 timer problem

Discussion in 'Electronic Basics' started by randomname, Sep 26, 2006.

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  1. randomname

    randomname Guest

    I'm working on the "time fountain" project and have run into probably
    the last of my problems. Here is the circuit (just strobing LEDs, and
    a motor):

    +------+ |
    +6V>--+--[1N4001>]--+------|Vcc | [LED]
    | |+ | | |K
    | [1000µF] | OUT|----+
    | | | |
    GND>--|-------------+------|GND 5|--[.1uf]--|GND
    | +------+
    | |
    | +----+----+
    | | |
    | [1N4001] [MOTOR]
    | | |
    | +------+ +----+----+
    +6V>--+--[1N4001>]--+------|Vcc | |
    |+ | | C
    [1000µF] | OUT|---[R]--B
    | | | E
    GND>----------------+------|GND 5|--[.1uf]--|
    +------+ GND

    The top timer just controls strobing LEDs, and appears to be working
    fine (though I have no real means to test it).

    The bottom timer, however, gives me problems. I'm using a 1uf cap, 1K
    for uptime, and 1K for downtime. (The configuration is such that one
    resistor controls the cap charge, the other controls the discharge)

    The motor is a tiny submersible 3vdc water pump. The problem is that
    the frequency of the 555 timer will alternate. Ive hooked up a piezo
    in parralel to the motor, so I can hear the frequency of the timer. (I
    dont have an oscilloscope)

    It will be high for a few seconds, then dip low for a few seconds, then
    go back high. When this happens, it changes the RPMs of the motor
    which changes the flow of water -- I need a constant flow of water. I
    just need the motor to run steady at a certain rate, which it does, but
    only for short bursts of time.

    I need the 555 to stay as constant as possible... but for some reason
    the 555 timer is giving me a hard time. Any suggestions? Thanks a


    Another note: when I first turn on the rig it will work fine for a
    minute or two, then it will start to give me problems. Don't know if
    that helps.
  2. Maybe if you could post the exact circuit of the timer that controls
    the motor, with all the parts and connections...
  3. default

    default Guest

    Maybe not what you are after, but if I were trying for a precise
    amount, particularly individual drops of liquid, I'd look into
    chemical metering pumps. I forget the name of the manufacturer, but
    someone makes a tiny (Ice Cube size) solenoid pump that is capable of
    very precise delivery with each stroke of the solenoid.

    I saw the thing at a pharmaceutical instrument trade show. Vicor may
    be the name of the company - but searching didn't turn up hits on a
    pump. Slick little pump - they had it making precise timed air
    bubbles and timed droplets of one fluid in another (immiscible) fluid
    (like those wave tank thingees they sell to executives to put on their
    desks, or the old lava lamp)

    From what you are saying, I get the idea that you are dealing with a
    centrifugal type (impeller) pump (similar to a car windshield washer,
    or boat bilge pump). For precise delivery a positive displacement
    pump will work much better - each revolution or stroke of a piston
    delivers a known amount of fluid and if you stop up the outlet the
    pump stalls.

    And if that is the idea - no pressure necessary - you could just use
    your pump to pump up a liquid to a small reservoir and let it overflow
    to maintain a constant head - then regulating the drips could be done
    with a small needle valve or pinch valve on some tubing. Motor speed
    of the pump isn't critical to delivery rate that way.

    One solution, with the pump you have, if you want pressurized water,
    may be to use it to pressurize a bladder tank similar to what well
    water systems use. Sounds farfetched; don't it? On a miniature
    scale, a balloon in a plastic enclosure. The bladder is in a rigid
    enclosure and water can inflate the balloon compressing the air around
    it (to provide a method of storing the small amount of pressure).
    Balloon mechanically/magnetically opens a switch and shuts down the
    pump until the pressure drops a little (or operates a linear
    potentiometer that works the pulse width modulator on the 555?) slick
    .. . .

    Build your own pump? I cobbled together a pump from a loud speaker
    and some strips of latex to use as check valves (ala aquarium pumps).
    Mine was to provide puffs of air across a spark gap to quench the
    spark - worked with 60 cycles to quench a 60 cycle spark. I only used
    one check valve since the fluid in the tube (air in my case) had
    inertia and once it was moving down the tubing it didn't want to come
    back during the refill stroke of the voice coil. (and the length of
    tubing was resonant at 60 hertz with air in it) - not for liquid but
    it wouldn't be a big deal to use a sheet of thin latex (like a dental
    dam from a drug store) to isolate the speaker cone from the fluid.
    (latex is fine with water but doesn't like hydrocarbon oils).

    It would be a piece of cake to modify an aquarium pump with a solenoid
    driver instead of the magnet/AC coil they use. The parts are liquid
    proof (plastic enclosure) Buena N diaphragm (from the looks of it) and
    silicone rubber check valves. Vary the delivery by varying the stroke
    with an adjustable stop on the solenoid driver so it limits the range
    of motion.

    Then you have Archimedes pumps, bucket pumps, etc if lifting water
    without the need for pressure is the game.

    Boggles the mind: don't it? I could have a lot of fun with this.
  4. randomname

    randomname Guest

    Wow! Thank you so much for providing me with all of these ideas. Ive
    looked into the "positive displacement pump" solution and found just
    the companies who might be able to help me out.. I just hope the cost
    isn't absurd.

    This page may contain the pump I'm looking for:

    Do you think the Series GB pump would work? It seems like if I get
    could the correct mL/rev and the right rev speed, I could get a perfect

    Again, thank you so much!

  5. default

    default Guest

    Yeah that looks like it (or its many cousins) could work.

    Since you seem to be playing with 555's and battery power, I figured
    this was more of a project to satisfy curiosity or for self
    satisfaction (low budget toy).

    And chemical metering pumps do tend to be expensive. They are made
    for chemical, pharmaceutical, industrial applications and those people
    have lots of money - and it ain't exactly a common item. They want
    absolute accuracy, a pump that will run for a long time before
    repairing, and usually in a harsh environment - that costs.

    Farmers use them too, for fertilizer and livestock applications - but
    it is still in a business context although they have less to spend.
    Farm pumps are likely to be high volume types.

    There the savings is usually one of chemicals that have a long life
    when in a "stock" concentration and very short life when in a
    "working" solution/dilution - the solution to the problem is mix the
    two just before applying them.

    What cost is absurd?

    I haven't been following the whole thread, so I haven't kept up with
    your quest. I was off for a week with the wife too . . . Is this,
    are you building a water clock?

    I had a deal where I had to fill and empty flasks in a robotic
    chemical assay application. I found a really slick pump to do the
    fill. Had to be within a fraction of a percent to volume.
    Pharmaceutical company and money is no object (unless, of course, I
    asked for a raise). Well anyhow this pump used compressed air on one
    side of a piston and liquid to be pumped on the other. A stop (bolt
    that ran into the end) adjusted the stroke length and delivery volume.
    Very accurate and virtually foolproof and maintenance free. Looks
    like it was made from schedule 80 PVC plumbing parts, with a little
    machining and hardware. Check valves were off the shelf parts - one
    way ball checks. Ingenuous and expensive but did the job

    Another thought for accuracy and cheap easy to make (but not pulse
    free) are peristaltic pumps. A hub spins with a motor. The hub has
    rollers around the periphery. A piece of tubing is stretched around
    ~180 to ~270 degrees of arc against the rollers with enough force to
    close the tubing where it touches the rollers (only works with low
    modulus(?) tubing like silicone). I was using one to fill vials with
    a 600 RPM drive and filled the vials to within a tenth of a percent,
    using timing to turn the pump on and off.

    You mentioned something about viscosity and drop size? I was a kid
    and watching TV in the 50's sometime. There was a show called "You
    Asked for It." Someone wanted to know what the largest drop size
    was, and they sure produced a prodigious drop. They showed people
    climbing up a ladder and dumping buckets into this large (6-8 foot
    diameter) ring with about a three foot height. The "drop" formed at
    the bottom of the ring and went into a huge tub.

    Well this thing, if my memory is right, was just a ring with a very
    fine mesh screen at the bottom and a layer of cloth resting on the
    screen. They had to start it off carefully by wetting the cloth until
    they had a few inches of water in it then just dumped buckets in it
    until it drop 'd through the screen. You could see the drop forming
    long before it dropped and it looked like it held a few hundred
    gallons. The ring was formed with a "bell" opening where they were
    pouring water, and it looked like the drop formed below with some
    margin - like there was a rim or something that prevented the drop
    from going out to the edge of the ring.

    That was a long time ago. I was a kid. It was a black and white TV
    and on an antenna - so perhaps there are gaps in my memory.

    They didn't say, or I don't remember, if they had any way to increase
    the surface tension of the water - I think not. I think the whole
    idea/experiment was predicated on the same idea as used by aerators on

    Before someone jumps in my shit - aerators work mostly by keeping air
    out of the pipe after the water is shut off - no air no drip (unless
    the washer is bad). They also entrain air into the delivery for
    esthetic reasons and help dissipate some off tastes that may be
    present, due to volatile chemicals in the water.

    I don't know if you can use that aerator thing I figure if accurate
    delivery of water is paramount you don't measure by the drop, so a
    drop must be necessary for a visual reason or for its impact when
    falling onto something.

    In absolute scientific terms a drop is a drop - but a drop at one
    temperature will weigh more or less as the temperature and density
    changes - if one were building a clock that needed a specific weight
    for the mechanism, for instance.
  6. The Time Fountain

    Look at the video.
  7. My solution and I tested it, was to use an aquarium air pump. But not to
    pump air, so it pumps water. You take the chamber out of the air pump so it
    will sit in the water basin. The tubing fits the outlet just like the air
    line did. The magnet that was inside is removed from the swing arm and
    attached to the rubber pump bulb. From there all that is needed is a coil
    positioned close to the magnet. Each current pulse on the coil will produce
    a drop of water. JTT
  8. default

    default Guest

    On dial up? Video? can they do that?

    I'm sort of text . . . very slow dial up. Yes, when you think of
    geographical area - not every one connects - and will never if
    Congress (corporations) have a say. There are compensations.

    I get the idea though. One wants a drip at precise intervals (?) and
    then strobes it with light and cameras to make it look like the drip
    (actually many drips) are in slow motion?

    Should be easy with an LED, 555 and dripping spigot. But I haven't
    never dun nothing like that so wouldn't no.

    That seems really simple. Reservoir idea should be perfect for as
    long as it needs to work for a camera - if this is for a
    demonstration in a science exhibit, a metering pump and some anti
    microbial solution in the working fluid would be better if school kids
    were to see it.

    What's the game? pictures or empirical discovery?

    My computer security?: don't use Outhouse, Exploder, Flash Etc.
  9. It'll download and then run.
    I know there are parts of the US that still don't have phones, or where 300
    baud is max dial up.
    Actually they detect the drops then fire the UV LEDs to sync with them. You
    can make the drops 'run upwards' by tweaking the syncing.
  10. default

    default Guest

    Good job.

    You can take a 10-32 bolt and use it to tap out a drill hole in
    plastic. (helps to score it - the tap - with some longitudinal
    gouges, but it isn't necessary - just to make a "proper" tap)

    With the tapped hole, you can use those "drip irrigation" fittings in
    the hardware store - then you can draw up liquid into the pump and
    pump it out - no need to submerge the pump.- but I figure with 60
    pulses per second timing should provide accurate delivery.

    So why remove the magnet? I don't understand that. make it a
    solenoid pump?

    Or perhaps you got a pump that would make uniform drops?

    Hey! Tell me more. are you driving it with 50/60 cycles, or driving
    it with a solenoid? What pump are you using?

    This is McGyver stuff,
  11. default

    default Guest

    Well it ain't that bad. I do's got's dialup. and at 50K.

    My problem is I can't stay with one topic long enough to download.

    Doubtless the pharmaceutical companies will have an answer for that -
    with side effects like: runny nose, depression, suicidal impulses, and
    death. I just ain't ready to go there.

    Well you know this thing about making the drops run up? We were doing
    that in the 60's and didn't use UV light (but did use zeon lamps which
    do produce some UV).

    It is called a "strobo tach" or."optical tach" these days - and they
    are on the internet
  12. randomname

    randomname Guest

    Yeah that looks like it (or its many cousins) could work.
    Well, I'd like the unit to cost as little as possible, because I'll
    probably be making a bunch and giving them as gifts (very expensive
    gifts). I might try to sell a few on eBay... considering the ones on
    the webpage sold for $400 each, preordered (for 6-8 weeks in the
    future, which is about now). So a pump under $50 would be great.
    I've looked on about 20 of these chemical/pharmaceutical/misc "fluidic
    specialists" websites and found lots of suitable pumps.. but only one
    site had a listed price (I've 'applied' to all the others, with as best
    specifications as I could.)

    Perhaps you could help me with this. Take a look and read their
    descriptions: (look for the CTS

    The store for the CTS pumps is here:
    and for the liquid is here:

    The LTC pumps cost double, and need at least 12volts. So I've ruled
    them out.

    However, the CTS pumps look like they could work. Especially the "low
    flow" pumps at the bottom. I've measured the flow row of my fountain
    when it drips at an optimal rate, and it turns out to be about
    ..08mL/minute. I measured it by weighing a cup, filling it for a minute
    with the perfectly dripping stream, then weighing it again. I'm
    assuming my tap water/highliter liquid solution is approximately 1g/ml.

    Anyway, the problem is the CTS line of pumps doesn't explicitly say it
    is meant for water. I'm wondering it will work anyway. I sure hope
    so, because I'd love to order one right now and get this thing working
    and very stable. I'd love to get rid of this valve and replace it with
    just controlling the PWM. Which leads into my next question, PWM
    should work the same with these pumps, right? It won't adversely
    effect performance, will it?

    And yet another question.. will the pulsation of one of these pumps
    affect the unit? I mean, do you think it will vibrate enough to shake
    the whole foutain and cause some disruption of the drops? I noticed
    they work with a weight off the shaft of the motor which seems like it
    will cause some wobble. I'm assuming that since it's so small it won't
    do much.

    On a side note, I found it astonishing how well these pumps react to
    pressure! They can pump water really high for being so small. My
    little impeller pump here has such a huge drop-off when the height of
    the fountain is raised. But I guess thats the principal behind
    "positive displacement," theres no way for the water to go but out the

    I hope you check out the video.. it shouldn't take longer than 5
    minutes to load.
    I'd love to learn how to make bigger drops using this method. I'm
    content with the current drop size, though. I might upgrade it by
    putting a piece of McDonalds straw (aka soda-pipe) at the end, since
    its much wider.

    As per the pump made from the aquarium pump... I'll look into this but
    I'd prefer a plug-and-play solution at this point. I'm hoping one of
    the several pump places I've contacted will be friendly enough to be
    like "we've got just the right pumpt for you... and it's a very common
    one. It'll be $30." We'll see, and I'll definitely keep you all

    Again, thanks so much for keeping up with this!

  13. default

    default Guest

    Don't have a lot of time to devote to this now
    Check out:

    Looks like the CTS and is surplus. They call it an air pump but they
    could be wrong - at $15 you could experiment

    Air pumps will work with other fluids if the materials are compatible
    - water is way more viscous too, the pump would have to turn slowly to
    pump water.

    Other sites for cheap pumps, when they have them (surplus) Look for pumps

    They all have interesting paper catalogs too.
  14. Look at model railroad accessories (like Faller or Vollmer). ISTR a tiny
    solenoid pump that ran waterwheels on some models.
  15. default

    default Guest

    I'm guessing the CTS pump wasn't intended for liquid - that isn't to
    say it wouldn't work with water - I just don't know. The problem with
    pumping liquid through an air pump is the density/viscosity is so much
    higher that it effectively stalls the pump - can't move out the outlet
    fast enough.

    Air pumps can be used to pump water indirectly by filling a vessel
    with water and using air to displace it. A three liter plastic soda
    bottle is an excellent pressure vessel (one of the home brewers tested
    a 20 ounce PET bottle to 125 PSI and it held without problems - I just
    put sugar, water and yeast in one and my 20 ounce bottle was teardrop
    shaped and held 40 ounces when it was finished fermenting - but it
    didn't break)

    You just need a stopper with two holes and a dip tube to go to the
    bottom then use the air pump to pressurize the head space. 15 pounds
    of pressure will raise water about 30 feet.

    Vibration may not be a problem you won't know until you try. It is
    very easy to just make a suspension so the vibration isn't coupled
    into the drop tube. For aquarium pumps I just put springs to each of
    the corners and mount it in a frame - I even used a similar technique
    to mount an air compressor in an attic - built a wooden frame and
    suspended it from the rafters on four springs (1/2 hp compressor with
    air tank). No noise in the lab below. When it was on the joists it
    made one hell of a racket.

    You seem to be killing yourself with all this fixation on getting
    uniform drop spacing. Why?

    If you look at the original device - he uses a PIC (overkill in my
    opinion) to trigger the strobe when a drop fell. That is easily done
    with two 555's. Using the conductivity detector to trigger the first
    timer to allow a delay, then a short time delay 555 to fire the

    The thing will work perfectly every time because the acceleration of
    the drops as they fall is governed by gravity and is consistent (so
    the strobe will always fire at the precise point in time when the drop
    is at a fixed distance from the nozzle. If you want them to look like
    they are moving upwards - that may still need consistent delivery to
    make it look fluid.

    It looks like U toob requires flash player. Flash player is spyware
    in my opinion

    - it defaults to leaving your camera and microphone open to sites you
    visit (if you have a camera or microphone).

    To change the privacy settings you have to visit a web site with Java
    Script enabled so they can set the privacy settings you select, and
    you have to trust that they do it.

    They have something similar to web cookies - that were intended to be
    non-removable tracking cookies.


    I won't have Flash player installed on my computer, and there is no
    alternative - so I can't use U toob.
  16. default

    default Guest

    On 2 Oct 2006 01:57:37 -0700, "randomname" <>

    Correct link to the pump

    Sensidyne # AA060INSNF40VC2. Precision, miniature air pump. Operates
    on 6 Vdc, 80 mA (no load). Minimum free flow, 1460 cc / min. Minimum
    Vacuum @ dead head, 9.1" HG (307 mbar). 1.55" x 1.22" x 0.68." Ports
    for 1/8" (3.2mm) ID tubing.
    CAT# PMP-6

    Your Price: $14.75 each
  17. randomname

    randomname Guest

    Sensidyne # AA060INSNF40VC2. Precision, miniature air pump. Operates
    Thanks again for the info.

    I've been browsing allelectronics to see how much it would cost to
    build 10 of these babies, and it's incredibly cheap. I never bothered
    to search or a pump! Can't believe they have it. I hope it can handle
    water... I have a feeling it won't, though. Seems like theyd advertise
    that it could be used for water.

    I've ordered this pump, along with the tronics for building another
    fountain. This time around I'm going to use a 556 timer instead of a
    555, so that I only need 1 1000uF cap, and to make everything better
    organized (especially since the breadboard I ordered has positive and
    negative rails on both the top and bottom. Score!)

    In the meantime, we'll see what these "fluidic professionals" say, if
    they bother to reply to a non-company such as myself.

  18. randomname

    randomname Guest

    I'll look into that right now..

    and I've find this little guy for only $3.. there are no specs though.
    Do you happen to know what voltage is the standard for these train
    set-ups? Hopefully <6v DC.

  19. Typically 12 - 20 VDC - but Marklin uses AC IIRC.

    That looks like the pump - my memory is that it runs off AC - it kind of
    'buzzes' at 60 cycles. This one is made in China.
  20. randomname

    randomname Guest

    Today I purchased a wall transformer from the dollar store (liars -- it
    was $3.59) that has 1.5, 3 4.5, 6, 9, and 12 volts, and works with 110
    or 220 volt inputs, and provides 500mA of current.

    So this replaces my 4 AA batteries, which would run weak after a couple
    of hours. Strange thing is, when set to 6v it really makes my set-up
    go crazy. The pump pumps way more liquid, and the strobe lights just
    go crazy.. they flash brightly and irradically.

    So I switched it to 3v and everything is fine. Pump runs very stable,
    and the LEDs are steady and bright. It's been running for over an hour
    completely stable (except for the normal hiccups and jitter caused by
    my crappy pump). The wall transformer is just warm (about 115 F), so I
    figure it's happy.

    I wonder why I need to set it to 3v. If i switch it to 220v mode, I
    need to crank it up to 12v for it to run about the same. If anyone can
    explain this I'm all ears.

    Oh well, it works!

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