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Discussion Starter · #1 ·
I am low on funds right now and want a project to work on. What better than to setup automated dosing for my tank.

After reading on this site. Or whatever I could understand, it looks pretty simple to make a peristaltic pump from a mechanical timer.
Has anybody here attempted this yet?

I have been surfing around trying to find an idea timer for this project, I came across some cheapy's on ebay, but its hard to tell what you are buying. I'd like to see the actual unit up close. Anybody know of some 24 mechanical timers that would be perfect for this project and don't cost to much?

I'd love any input if you have any. Hopefully all goes well and will be able to show a nice looking pump in here.
 

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There are some versions of that kicking around, search for 'cheap autodosing' or something like that, many a syringe based setup. I haven't seen the 'peristaltic' timer here though. It looks like those are the basic timers seen in every place that has hardware.
 

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most cheap timers have those notches every 15 or 30 minutes and the dail does not come off. you need to find older timers that came with 4-8 removable tabs where you'd lift the dail off, insert the tabs, then re-seat the dail. those are the type you can then screw around with. I suppose that old tab design fell out of favor since people kept losing their unused tabs.
 

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Discussion Starter · #5 ·
most cheap timers have those notches every 15 or 30 minutes and the dail does not come off. you need to find older timers that came with 4-8 removable tabs where you'd lift the dail off, insert the tabs, then re-seat the dail. those are the type you can then screw around with. I suppose that old tab design fell out of favor since people kept losing their unused tabs.
Hey spypet, thanks for that info. I actually just got back from the hardware store and picked up two of these. Intermatic Lamp Timer. I havn't opened them up yet incase I might have to return them now. Is this what you were talking about with the tabs?

I think I will open one of them and see if its possible to use this timer.
They only cost me $4.97 ea.
 

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no, that dial won't pop up.
you need the tabs the come off the sides, not the top, since the side
removing tabs require you to pull off the dial in order to change them.
you are more likely to see it on an appliance timer since those large
metal tabs had the strength to throw a bigger toggle switch assembly.

 

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Discussion Starter · #7 ·
spypet, no actually I think it will work.
I disassembled one of them.


I can drill holes into the dial.
 

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Now, the question is how to speed up the timer and then place it on a timer that operates it for a short period of time...

Electronics people?
 

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Discussion Starter · #9 ·
I was thinking if this thing spins constantly I could build the pump and test to see how much it pumps out in one day and do the math to create the correct mixture of fertilizers and dose it like so.
 

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After reading on this site. Or whatever I could understand, it looks pretty simple to make a peristaltic pump from a mechanical timer.
Has anybody here attempted this yet?
I have tried this and given up with that specific design. With regular silicone tubing, you need a lot of pull to make this work. I didn't have the right timers for this. But give it a try and see if you can make it work.

I am thinking about making one similar to commercial peristaltic pumps, where rollers squeeze the tubing against a rigid housing. Just haven't found the right gizmo for this yet.
 

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Discussion Starter · #12 ·
I have tried this and given up with that specific design. With regular silicone tubing, you need a lot of pull to make this work. I didn't have the right timers for this. But give it a try and see if you can make it work.

I am thinking about making one similar to commercial peristaltic pumps, where rollers squeeze the tubing against a rigid housing. Just haven't found the right gizmo for this yet.
I found some good tubing I think might be perfect for the job.
It's from Tygon, called Tygoprene.
Designed specifically for use in peristaltic pump applications, Tygoprene® pump tubing maintains a pump life of over 500 hours. With a durometer hardness of Shore A60, it is extremely flexible and exhibits superior flex life, reducing downtime due to pump tubing failure. Tygoprene® pump tubing is translucent in color and has excellent chemical resistance to a wide range of fluids, including acids and bases. It can be considered an alternative to silicones and PVC when longer pump life is required. Low extractables. Temperature resistant up to 250°F. Meets FDA and NSF 51 criteria. PSI listed at 73°F.
 

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I have tried this and given up with that specific design. With regular silicone tubing, you need a lot of pull to make this work. I didn't have the right timers for this. But give it a try and see if you can make it work.

I am thinking about making one similar to commercial peristaltic pumps, where rollers squeeze the tubing against a rigid housing. Just haven't found the right gizmo for this yet.
2 things:
1) did you try this with surgical tubing at HD?
2) Wasser, If you have timers that are strong enough to pull and push a syringe, why couldn't you use a similar layout to what is described in the link, but have the tubing line a rigid cylidical housing so the roller will press against it?
 

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I'm not sure what your intentions were with the timer but if it's the drive motor I don't think it nor the bearings have the guts to sustain that sort of work. Nice idea, though: In 24-hours you could force one revolution of solution into the tank. I don't know the details but once you get the mechanics down (and it's NOT a trivial undertaking) you could use a 24 hour timer to trigger an electronic timer circuit that runs for however many second you want. Set your timer to turn on and off several times per day and you're set. You may be able to build a circuit that resets with a 555 timer chip.

P.S. The first DIY project shown above is way beyond most folks garage.

Here's your lead to a 24 hour electronic timer to turn your pump on. I can't testify to the accuracy of the circuit but it gives you a starting point.
http://www.cappels.org/dproj/garden_timer/Garden_timer.html
 

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I found some good tubing I think might be perfect for the job.
It's from Tygon, called Tygoprene.
Designed specifically for use in peristaltic pump applications, Tygoprene® pump tubing maintains a pump life of over 500 hours. With a durometer hardness of Shore A60, it is extremely flexible and exhibits superior flex life, reducing downtime due to pump tubing failure. Tygoprene® pump tubing is translucent in color and has excellent chemical resistance to a wide range of fluids, including acids and bases. It can be considered an alternative to silicones and PVC when longer pump life is required. Low extractables. Temperature resistant up to 250°F. Meets FDA and NSF 51 criteria. PSI listed at 73°F.
Thank you for the link. If you buy the 50ft roll, I might be interested in a few feet. :smile:
 

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2 things:
1) did you try this with surgical tubing at HD?
2) Wasser, If you have timers that are strong enough to pull and push a syringe, why couldn't you use a similar layout to what is described in the link, but have the tubing line a rigid cylidical housing so the roller will press against it?
1) No I didn't know HD had surgical tubing...

2) That's exactly what I am thinking about. The thing holding the rollers would need to be centered with high precision, not sure how possible that is.

Another modification would be to use (instead of the cylindrical housing) a metal spring that pushes the tubing against the rollers, which can probably be built with less precision.

So many things to try, so little time... :icon_roll
 

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I'm not sure what your intentions were with the timer but if it's the drive motor I don't think it nor the bearings have the guts to sustain that sort of work. Nice idea, though: In 24-hours you could force one revolution of solution into the tank. I don't know the details but once you get the mechanics down (and it's NOT a trivial undertaking) you could use a 24 hour timer to trigger an electronic timer circuit that runs for however many second you want. Set your timer to turn on and off several times per day and you're set. You may be able to build a circuit that resets with a 555 timer chip.
I think the intentions are to let that run continuously. Even so, the quantities dispensed will be very small, maybe too small for anything but the smallest tanks. Unless you find a way to magically speed up that timer...
 

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Plus there might be the mild issue of torque, but that will fluctuate higly by the make and model of the timer.. I don't know how much pressure it could exert on the hose until the maniacal gear ratio stopped the motor dead. Most of the ones I used in science class had a springloaded plate under the hose on the side opposite to the rotor-roller to make up for the imbalance in the rotor design. perhaps and old tape/vcr transport could yeild some good parts/stepper motors and springs.

-Rich
 
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