555 timer problem

Maybe if you could post the exact circuit of the timer that controls the motor, with all the parts and connections...

-- John

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.

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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 drip!

Again, thank you so much!

-Sam

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 beautifully.

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 faucets.

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.

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The Time Fountain

Look at the video.

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

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.

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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.

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,

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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

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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:

The store for the CTS pumps 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 pump.

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 posted.

Again, thanks so much for keeping up with this!

-sam

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)

They all have interesting paper catalogs too.

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Look at model railroad accessories (like Faller or Vollmer). ISTR a tiny solenoid pump that ran waterwheels on some models.

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 strobe.

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.

See

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

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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

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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

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

-sam

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

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!

-sam