Thanks for mentioning the trigger voltage. I think the timer I chose has a 12 volt output, but I need to check that.
Trying to do the math on an affordable HPA system
- Thread starter Larry3215
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Post a link when you start that one. I have dreams of building a controller one day waaaaay down the road
I'll post pics. I actually have no shame, and I dont give a hoot what anyone thinks about my builds. I have a bad habit of bread boarding something in a hurry just to see if it works as expected. I always have the full intention of making it pretty - at some later point - but I usually leave it alone as soon as its working the way I want it to. I seem to be a function over form kind of builder. Well, unless its one of my planes. For them, Im will to spend (as little time as possible) making them presentable
I found some mosfets on digikey that are reasonable - 30V 60A, TO220 for $1.57ea
Its been too long - what schottky do you recommend? I was going to order some 1N5817, but thought I should double check. These are fast and low loss, but only 20 volt, 1amp.
Oh, the timer passes the supply voltage through, so it would be 12v on Pin.
I probably should have waited to pick @Atomizer 's brain some more, but I went ahead and ordered parts to get started. Im going to leave my existing LPA setup running so I can practice cloning while I play with this new, to me, tech. I plan to set it up and do some misting tests before I dismantle the existing setup.
I decided to start with the lower flow - .7gph - no drip nozzles.
https://www.dripworks.com/superfine-misting-nozzle
It looks like they will be easier to get the total flow numbers down into the ranges Atomizer recommends. If I increase the chamber height to 26", that gives me a volume of around 50 gallons/189 liters.
At the low end, he recommends .02 to .04ml/gal/on cycle.
.7 GPH - .736 ml/sec
.02 x 50 gals = 1ml/sec
So the shortest on time for a single mister to achieve .02 to .04 ml, would be 1.4 to 2.8 seconds of on time. Two misters would be .7 to 1.4 seconds, etc. If I go with 4 misters, the shortest time drops to .3 seconds, which seems awfully short, but I can try that and see how it works. The longest times for a single mister would be 4.2 seconds, and four heads would be 1 second or so. My timer can only do .1 sec intervals, so Im rounding off.
I plan to start with two misters mounted near the bottom of the chamber pointing more or less up, but slightly angled to create some swirling action in the chamber. After I see what kind of mist that produces and how long it hangs, how well it fills the chamber, measure the actual discharge volume, etc, I will decide if I need to try other options - like 3 or 4 heads instead of two.
These fabric pots should make it easy to move misters around, add or remove them etc. Assuming I can get the mist quality in the ball park, I will start by seeing how well I can root clones, and or start seeds in the chamber. I can play with that until it cools down enough to do a full grow.
I was reading some old posts and one of Atomizers ideas for changing the cycle times between day/night gave me an idea.
I might end up needing four misters for good coverage, but four may end up putting out more spray volume than is ideal at my shortest spray times. One way to handle that might be to split the misters into two pairs that fire alternately. Maybe switching between them every 10-15 minutes or so?
I could probably build an arduino setup that would do that easily as far as the alternating timers, but I am not good at arduino programming - at all. An easier way for me would be just to use two timers and additional mosfet power switchs or relays. Im thinking maybe use two timers and two mosfet switches to switch back and forth between the two sets of misters, but its just a vague idea at the moment. I havent worked out the exact details for the best way to do that.
All the parts should be here over the next couple of weeks. That will give me at least two months of play time to get it more or less dialed in before it cools down enough to start growing.
I decided to start with the lower flow - .7gph - no drip nozzles.
https://www.dripworks.com/superfine-misting-nozzle
It looks like they will be easier to get the total flow numbers down into the ranges Atomizer recommends. If I increase the chamber height to 26", that gives me a volume of around 50 gallons/189 liters.
At the low end, he recommends .02 to .04ml/gal/on cycle.
.7 GPH - .736 ml/sec
.02 x 50 gals = 1ml/sec
So the shortest on time for a single mister to achieve .02 to .04 ml, would be 1.4 to 2.8 seconds of on time. Two misters would be .7 to 1.4 seconds, etc. If I go with 4 misters, the shortest time drops to .3 seconds, which seems awfully short, but I can try that and see how it works. The longest times for a single mister would be 4.2 seconds, and four heads would be 1 second or so. My timer can only do .1 sec intervals, so Im rounding off.
I plan to start with two misters mounted near the bottom of the chamber pointing more or less up, but slightly angled to create some swirling action in the chamber. After I see what kind of mist that produces and how long it hangs, how well it fills the chamber, measure the actual discharge volume, etc, I will decide if I need to try other options - like 3 or 4 heads instead of two.
These fabric pots should make it easy to move misters around, add or remove them etc. Assuming I can get the mist quality in the ball park, I will start by seeing how well I can root clones, and or start seeds in the chamber. I can play with that until it cools down enough to do a full grow.
I was reading some old posts and one of Atomizers ideas for changing the cycle times between day/night gave me an idea.
I might end up needing four misters for good coverage, but four may end up putting out more spray volume than is ideal at my shortest spray times. One way to handle that might be to split the misters into two pairs that fire alternately. Maybe switching between them every 10-15 minutes or so?
I could probably build an arduino setup that would do that easily as far as the alternating timers, but I am not good at arduino programming - at all. An easier way for me would be just to use two timers and additional mosfet power switchs or relays. Im thinking maybe use two timers and two mosfet switches to switch back and forth between the two sets of misters, but its just a vague idea at the moment. I havent worked out the exact details for the best way to do that.
All the parts should be here over the next couple of weeks. That will give me at least two months of play time to get it more or less dialed in before it cools down enough to start growing.
Flow numbers only apply if you have full mist coverage (#1 priority) comprising 5-80 micron droplets. One hydraulic nozzle may fulfill the flow rate requirement but it wont provide full coverage on its own. Increasing the number of nozzles to provide the coverage increases the flowrate so you will be forced to use shorter pulses to compensate and it still may not ne enough. Its much easier to achieve with AA nozzles due to their superior response, coverage and flowrate, the downside is cost.
Yeah, that became apparent as I was doing the calculations. More coverage means more flow rate and less flow rate means less coverage.
Ive been trying to set this up to get flow rates close to what you have been recommending, but that is requiring very short on times with 4 misters. Im concerned about the quality of the mist droplets due to the open/close ramp times of the solenoids, tubing flex/expansion etc. Any solenoid is going to have a certain time it takes to open or close fully. During that initial opening or closing time, the pressure and flow rates will be ramping up or down - which will mean varying sizes of droplets. I have no idea what that time is for these cheap solenoids, but as you shorten the on times, the ramp up/down time becomes a greater % of the total - lowering the droplet quality.
Im trying to minimize those issues by using one solenoid per mister, mounting them very close to the solenoids, and using no drip misters.
What do you think of the idea of splitting the misters into groups, and firing them alternately on some schedule - say changing every few minutes?
It would take some custom programming on something like an arduino to switch between pairs on every discharge. I would think it would work well enough if you let one pair fire a a dozen times then changed to the other pair, and so on.
I could do that just by adding one more timer and another mosfet switch or a relay.
Another option would be to lower the spray pressure, but no one seems to recommend that. The specs imply that the droplet size will stay the same over the entire pressure range from about 40 PSI on up, with just the flow rate changing. I am not sure I believe that.
Ive been trying to set this up to get flow rates close to what you have been recommending, but that is requiring very short on times with 4 misters. Im concerned about the quality of the mist droplets due to the open/close ramp times of the solenoids, tubing flex/expansion etc. Any solenoid is going to have a certain time it takes to open or close fully. During that initial opening or closing time, the pressure and flow rates will be ramping up or down - which will mean varying sizes of droplets. I have no idea what that time is for these cheap solenoids, but as you shorten the on times, the ramp up/down time becomes a greater % of the total - lowering the droplet quality.
Im trying to minimize those issues by using one solenoid per mister, mounting them very close to the solenoids, and using no drip misters.
What do you think of the idea of splitting the misters into groups, and firing them alternately on some schedule - say changing every few minutes?
It would take some custom programming on something like an arduino to switch between pairs on every discharge. I would think it would work well enough if you let one pair fire a a dozen times then changed to the other pair, and so on.
I could do that just by adding one more timer and another mosfet switch or a relay.
Another option would be to lower the spray pressure, but no one seems to recommend that. The specs imply that the droplet size will stay the same over the entire pressure range from about 40 PSI on up, with just the flow rate changing. I am not sure I believe that.
Another thing thats become clear, is that very few people running HPA actually get the flow numbers down to the levels you recommend. Actually, I dont think I have seen anyone with an HPA system using on times and total flow rates as short as you suggest. Most seem to be putting out at least an order of magnitude more flow/day.
Your theories on this subject make very good sense to me, so Im hoping to get a little bit closer
Your theories on this subject make very good sense to me, so Im hoping to get a little bit closer
All the parts I think I will need are ordered, and some have arrived already. Thanks to some of the cost saving tips from earlier, Im only $4 over my $300 budget, and that includes shipping and tax on everything, so Im happy about that. I will still need to spend another few $$ on misc small items, but not much.
Im going to start testing with two nozzle/solenoid setups and see how that goes. If I need 4 nozzles, I will need to order two more solenoids.
This is a top view of the layout Im going to try first for the root chamber. I'll use a 30 gallon fabric pot 24" diameter x 16" tall. Depending on how those tests look, I may stitch two together to increase the height to around 26" for a total volume of up to 50 gallons. Im going to try angling the nozzles in different directions, angles until I get something that looks good. This is a crude drawing of the layout with two plants in 3" net pots. The drawing shows 4 nozzles, but Im only going to start with two.
In order to try to keep the total flow rates down, and still have reasonable ON times, and enough nozzles for good coverage, Ive decided to try the idea of firing the nozzles, or pairs of nozzles, alternately instead of having them both ON at the same time. This requires two timers as far as I can see. The primary timer will set the ON/OFF times. With say a 1 sec ON time and 60 sec OFF time to start. That timing signal will run to all of the nozzles through two separate DIY mosfet switches, like dstroy showed above. They will switch the solenoids ON/OFF.
The second timer relay will be set to what ever time I want to switch between sets of nozzles. That SPDT relay will turn the power ON or OFF to the mosfet switches in an alternating sequence. That will turn the power ON to one pair of nozzels for say 5, or 10 or 15 minutes, then turn that pair off and power the second pair of nozzles for the same 5, or 10, or 15 minutes, then repeat.
So for a pair of nozzles, #1 would fire on its basic cycle of 1 ON , 60 OFF for a total of say 5 minutes. Then #2 would fire the same way, alternating back and forth. For 4 nozzles, #1 and #3 would fire together to swirl the mist clockwise, then 2 and 4 would fire together to swirl the mist counter clockwise. With two misters, the swirl would always be in the same direction, so as far as coverage, 4 nozzles would be better I think. I will go with 4 nozzles if I can get the total flow rates down low enough, and with good mist quality - I hope!
The only downside I can see to this alternate timing is that at the end of every 5 minute cycle, the primary ON/OFF cycle will be interrupted at some random point. That means the once every 5 or 10 or what ever minutes, the ON time or the OFF time will be non-standard. It could be cut down to almost nothing or be almost twice its normal ON or OFF time. With a ten minute cycle time, that means 1 in 10 cycles will be off to some degree. Increasing the cycle time further will decrease the error rate. I doubt that extending the OFF times 1 in10 will be an issue. Doubling the ON times will of course over spray to that extent, but I dont know how bad that would be. The second timer can go up to 1 hour between cycles, so I have that option. Im assuming the roots will tell me if I have it wrong or not.
A custom programmable timer/relay setup could eliminate that problem, but thats beyond my design and programming skills..
The primary timer I have has no relays, but the secondary timer uses cheap mechanical relays for the SPDT switch. Im going to use it as is for testing, but will replace it with another DIY solid state SPDT for the grow.
Im going to start testing with two nozzle/solenoid setups and see how that goes. If I need 4 nozzles, I will need to order two more solenoids.
This is a top view of the layout Im going to try first for the root chamber. I'll use a 30 gallon fabric pot 24" diameter x 16" tall. Depending on how those tests look, I may stitch two together to increase the height to around 26" for a total volume of up to 50 gallons. Im going to try angling the nozzles in different directions, angles until I get something that looks good. This is a crude drawing of the layout with two plants in 3" net pots. The drawing shows 4 nozzles, but Im only going to start with two.
In order to try to keep the total flow rates down, and still have reasonable ON times, and enough nozzles for good coverage, Ive decided to try the idea of firing the nozzles, or pairs of nozzles, alternately instead of having them both ON at the same time. This requires two timers as far as I can see. The primary timer will set the ON/OFF times. With say a 1 sec ON time and 60 sec OFF time to start. That timing signal will run to all of the nozzles through two separate DIY mosfet switches, like dstroy showed above. They will switch the solenoids ON/OFF.
The second timer relay will be set to what ever time I want to switch between sets of nozzles. That SPDT relay will turn the power ON or OFF to the mosfet switches in an alternating sequence. That will turn the power ON to one pair of nozzels for say 5, or 10 or 15 minutes, then turn that pair off and power the second pair of nozzles for the same 5, or 10, or 15 minutes, then repeat.
So for a pair of nozzles, #1 would fire on its basic cycle of 1 ON , 60 OFF for a total of say 5 minutes. Then #2 would fire the same way, alternating back and forth. For 4 nozzles, #1 and #3 would fire together to swirl the mist clockwise, then 2 and 4 would fire together to swirl the mist counter clockwise. With two misters, the swirl would always be in the same direction, so as far as coverage, 4 nozzles would be better I think. I will go with 4 nozzles if I can get the total flow rates down low enough, and with good mist quality - I hope!
The only downside I can see to this alternate timing is that at the end of every 5 minute cycle, the primary ON/OFF cycle will be interrupted at some random point. That means the once every 5 or 10 or what ever minutes, the ON time or the OFF time will be non-standard. It could be cut down to almost nothing or be almost twice its normal ON or OFF time. With a ten minute cycle time, that means 1 in 10 cycles will be off to some degree. Increasing the cycle time further will decrease the error rate. I doubt that extending the OFF times 1 in10 will be an issue. Doubling the ON times will of course over spray to that extent, but I dont know how bad that would be. The second timer can go up to 1 hour between cycles, so I have that option. Im assuming the roots will tell me if I have it wrong or not.
A custom programmable timer/relay setup could eliminate that problem, but thats beyond my design and programming skills..
The primary timer I have has no relays, but the secondary timer uses cheap mechanical relays for the SPDT switch. Im going to use it as is for testing, but will replace it with another DIY solid state SPDT for the grow.
dstroy
Well-Known Member
You might not need a solenoid for every nozzle. As long as the solenoid can meet the flow requirements you can have as many nozzles per solenoid as you like.
One second every 60 seconds is too much. Probably way too much (almost twice my max worst case spray duration). It’s better if it’s less than 3:300 on
ff. But it’s ALSO better to not have dead plants so start high and bring it back slow until you understand your systems behavior. Then try the real weird shit like sub 1s feed times. But really, you’re just always trying to give just the right amount of food and not too much or too little, that’s the whole premise, precise control. Precision.As long as the mist fills the whole chamber you’re good. Do not over complicate this. It just has to be all the way full no more no less.
Worrying about the directionality of the mist is strange to me, I’m not sure why it’s concerning you. If you’re concerned about full coverage, ensure that your spray pattern is adequate. The kinetic energy of the water droplets is enough to penetrate the densest rootballs.
You should teach yourself some more electronics beyond basic FET switching and maybe some programming. Will make your life easier and you’ll save a lot of money. You can do anything you can imagine to help yourself with an MCU and some time to think about how to best put it to use. Makes it affordable to do one-offs or complicated industrial processes. It’s a fun hobby too, solving circuits that will be useful to you is rewarding personally.
Good luck
My swirl theory came from not having any real world experience, and some bad assumptions based on partial understanding of the process. In other words, Im ignorant
I assembled the pump, check valve, gauge, one solenoid and one nozzle today for a quick test. You're correct. There is no swirling, or at least not enough to worry about with these nozzles. These nozzles dont have anything like the throw that Atomizers AA nozzles do.
So, I have an extra timer. Maybe I can return it
You're right that learning more about electronics and programming would be a useful thing, but Im not likely to do that. I started out building ham gear from military surplus, and parts I salvaged form old TV's and radios when I was in 8th grade in the late 50's - all vacuum tubes! Remember the Radio Amatures Handbook? But I never stayed with it as far as transitioning to solid state devices. I know enough or can puzzle my way through it to put together simple circuits - like these mosfet switches, or chargers etc, but thats about it. I have also done some basic, fortran, assembly, and SQL programming at various times, but again, never for long enough to really get any good at it. I'm just not a good programmer and do not enjoy it. I dont think I have the right mind set for it.
Thanks for the help!
I assembled the pump, check valve, gauge, one solenoid and one nozzle today for a quick test. You're correct. There is no swirling, or at least not enough to worry about with these nozzles. These nozzles dont have anything like the throw that Atomizers AA nozzles do.
So, I have an extra timer. Maybe I can return it
You're right that learning more about electronics and programming would be a useful thing, but Im not likely to do that. I started out building ham gear from military surplus, and parts I salvaged form old TV's and radios when I was in 8th grade in the late 50's - all vacuum tubes! Remember the Radio Amatures Handbook? But I never stayed with it as far as transitioning to solid state devices. I know enough or can puzzle my way through it to put together simple circuits - like these mosfet switches, or chargers etc, but thats about it. I have also done some basic, fortran, assembly, and SQL programming at various times, but again, never for long enough to really get any good at it. I'm just not a good programmer and do not enjoy it. I dont think I have the right mind set for it.
Thanks for the help!
You`re not ignorant, you`re just in the transition phase between what you imagined would happen (swirl / vortex) and what actually happened 
Just to clarify, the flowrate capacity of a solenoid can run a bunch of nozzles but when precise control is the goal, one nozzle per solenoid (zero pipework) provides the best response.
Just to clarify, the flowrate capacity of a solenoid can run a bunch of nozzles but when precise control is the goal, one nozzle per solenoid (zero pipework) provides the best response.If you define ignorance as a lack of knowledge, then I am full of it
Fortunately, this particular 'lesson learned' wasnt too expensive.
Yeah, I got that about control from your earlier posts. Im trying to get as much control as possible as cheaply as possible - and I know those are goals that dont mesh well.
Fortunately, this particular 'lesson learned' wasnt too expensive.
Yeah, I got that about control from your earlier posts. Im trying to get as much control as possible as cheaply as possible - and I know those are goals that dont mesh well.
Well crap. The Tefen "No Drip" nozzles I chose make some ok (I think) looking mist, but they drip!
At the end of each cycle, the two I have set up for testing drip some nice fat drops every single time the solenoid shuts off. One of them only drips a single drop, but the second one drips three to four drops. I tested all 5 of the ones I got and they are all about the same - 1 to 4 drops after the solenoid closes depending on how they are pointed. When they point down, they drip more. I guess the chamber after the no drip valve is emptying out.
Do all nizzles of this type do this? How about the Hypro's?
Also, now that I have them shooting into my 45 gallon root chamber, its pretty obvious Im going to need at least 4 to "fill the chamber".
I returned the timers I originally chose (gotta love Amazon for easy returns), and ordered the one recommended in my original thread. I need to stop ordering parts at 2AM when Im half stoned - and - I need to read the manual before I order stuff. Both of the ones I chose have analog inputs to set the timing rather than digital. The new timer and the accumulator tank should be here tomorrow, so I can do more/better testing after I get them hooked up.
At the end of each cycle, the two I have set up for testing drip some nice fat drops every single time the solenoid shuts off. One of them only drips a single drop, but the second one drips three to four drops. I tested all 5 of the ones I got and they are all about the same - 1 to 4 drops after the solenoid closes depending on how they are pointed. When they point down, they drip more. I guess the chamber after the no drip valve is emptying out.
Do all nizzles of this type do this? How about the Hypro's?
Also, now that I have them shooting into my 45 gallon root chamber, its pretty obvious Im going to need at least 4 to "fill the chamber".
I returned the timers I originally chose (gotta love Amazon for easy returns), and ordered the one recommended in my original thread. I need to stop ordering parts at 2AM when Im half stoned - and - I need to read the manual before I order stuff. Both of the ones I chose have analog inputs to set the timing rather than digital. The new timer and the accumulator tank should be here tomorrow, so I can do more/better testing after I get them hooked up.
Before I order more parts for the spares box, clould you suggest a part number?
On the hypros, someone suggested the 301AFD0.7-80. These also come with an optional 200 mesh strainer, which I was thinking might be a good idea. These are the lowest GPM I can find with no drip.
I cant find anything on the netafim website that looks appropriate?
On the hypros, someone suggested the 301AFD0.7-80. These also come with an optional 200 mesh strainer, which I was thinking might be a good idea. These are the lowest GPM I can find with no drip.
I cant find anything on the netafim website that looks appropriate?
Anti Drain Valve`s
(sigh) I keep forgetting that asking for nozzle details is off limits, or over the line, or what ever. I'll try to remember that in the future. Doesnt make it easy for a newbie on a limited budget to join the club though.
Thanks for the definition. Its dificult to learn something new if you dont know what the acronyms stand for.
Thanks for the definition. Its dificult to learn something new if you dont know what the acronyms stand for.
You have the answer from the "someone" who suggested the hypro model number. If it was off limits they wouldnt have posted the number Hypro`s work well firing upwards in 16" deep chambers and firing downwards in 39" deep chambers, they are short throw (around 12"), hollow cone. Four upward firing nozzles will service a 2.5ft square chamber (~225L) . Netafim coolnet and coolnet pro`s are long throw ,full cone nozzles, more suited to long narrow chambers like 16ft x 2ft (1500L). At the end of the day, you need to decide if a particular nozzle type will work for your chamber or application, then you spend the cash and see if your right.
Hypro`s work well firing upwards in 16" deep chambers and firing downwards in 39" deep chambers, they are short throw (around 12"), hollow cone. Four upward firing nozzles will service a 2.5ft square chamber (~225L) . Netafim coolnet and coolnet pro`s are long throw ,full cone nozzles, more suited to long narrow chambers like 16ft x 2ft (1500L). At the end of the day, you need to decide if a particular nozzle type will work for your chamber or application, then you spend the cash and see if your right.