Micro solenoids for CO2 regulators

[macdaddynick1]

I think 50 psi might not be necessary since running it at a higher psi than 10-15 makes the bubble size too big for our application. Big bubbles will make it hard to finetune, although getting a higher rated solenoid might be good to have just in case.

[macdaddynick1]

Any updates?

[theatrus]

Should have something up this weekend. Didn't have the right parts in hand, and I'll get my test PCB tomorrow or so.

[theatrus]

Sneak peak: yes it does work. Basic skills with 555 timers confirmed



More details later

[macdaddynick1]

Originally Posted by theatrus

Sneak peak: yes it does work. Basic skills with 555 timers confirmed



More details later

So I was hoping I would be able to build one for myself, after looking at this. I am realizing this might be out of my league. However, I love learning how things are made, so I am definitely following. also how does one build a circuit board ?

[ravi197699]

Where did you get that board, I looked for 555 timer and they are 0 - 9999 seconds delay timers, I am not sure if they are going to work..

[oreo57]

Originally Posted by ravi197699

Where did you get that board, I looked for 555 timer and they are 0 - 9999 seconds delay timers, I am not sure if they are going to work..

Only used as an interval timer not an on/off period timer..
Like on/off once per second. so on/off and delay.
Think of it as PWM for gas..
Will (actually does as it is already in a production unit) work fine.

[theMerchant]

Good info, i would buy your kit.

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[macdaddynick1]

Originally Posted by theMerchant

Good info, i would buy your kit.

Sent from my SM-N910T using Tapatalk

I think he said OSHpark website

[theatrus]

Those board are made at OSHPark because its great for low volume and the quality is really high. However, its expensive if you really only want one board.

https://oshpark.com/shared_projects/kJ0Pkzaz

I'll upload the Gerber and Drill files (the "manufacturing output" files needed to make the board) if you want to send them somewhere - usually I put these under a CERN Open Hardware License.

That said, I have two left of the OSHPark boards, yours for the price of postage

The board is absolutely not essential, you can build the circuit easily with a soldering iron and a vero-board (or other similar prototype board) since its all through-hole parts. The board does make it fool proof (just load components, apply soldering iron). If there is enough interest, the cheaper path is to get a medium size lot from one of the Asian suppliers (Elecrow, PCBWay, DirtyPCBs, etc) which will give you a bunch for $0.50-$2 a board.

I'm going to put up a BOM (bill of materials) as well in a bit. I made some tweaks in component values (R4 is now a 2.2k resistor and not a wire/ 0 ohm). The on-time of the pulse is about 30ms, and I'm going to do some experiments with actual CO2 flowing to see if I should change it.

[theatrus]

The BOM as actual parts:

https://octopart.com/bom-tool/KsaVM9dL

Most of these parts are common "part kit" parts - if you have stuff laying around, the values used are very common (2.2K resistor, 220 ohm resistor, 10k linear pot, red LED, 220uF capacitors, 0.1uF capacitor, 555 timer). The exact brand here is not essential by any means.

I'd personally just grab the set from Mouser/Digikey, since the cost of shipping a single part will outweigh the actual order price. I have parts laying about (except power jacks, thought I had a stash but ran out).

[oreo57]

Ok, just to put it in words..
The "on" time is now fixed at 30ms..(curious as to what it was at 0 ohms)
The # of on times (per minute?) is set by the pot....

[theatrus]

Originally Posted by oreo57

Ok, just to put it in words..
The "on" time is now fixed at 30ms..(curious as to what it was at 0 ohms)
The # of on times (per minute?) is set by the pot....

For this BOM, yes. The on time can be adjusted by changing the value of R1, or adding a second pot in parallel with it (or just using the pot, etc). I'm going to experiment a bit and see how low R1 can go realistically with the valve in place.

R4 was a zero ohm since it was in series with the off-time pot. But an off-time of zero isn't particularly useful, and you might want a longer off time in some scenarios, hence I'm recommending also loading a 2.2k resistor there.

[theatrus]

In the realm of "things I messed up"

- R1 is specified as a 1/4W resistor. It really needs to be 1/2W or higher. I think a common 1W will fit - need to confirm. There is about a 50mA draw over this, and at 12V... I updated the BOM and will do a fit check.
- R4 should remain as a 0-ohm wire jumper, since its on the wrong side of the diode. Instead, add a 2.2k resistor in series with the pot (free wire). If I make a new board I'll fix this.

[Opcn]

Since saltwater is what killed the last one, is there a reason other than ~$12+ in price to go with the EV-2-12-H over the CR-EV-2-12-H ?

[theatrus]

Originally Posted by Opcn

Since saltwater is what killed the last one, is there a reason other than ~$12+ in price to go with the EV-2-12-H over the CR-EV-2-12-H ?

Great question - for the price difference it may be worth trying.

[Bgsutton]

What size plastic enclosure do you recommend to house all the components?

[AZReefRat]

Have you looked at hooking this up to a controller or something DIY that could make adjustments to Off-Time Pot based on Ph probe readings?

[lighthouze08]

Just wanted to thank Theatrus for the work you put into the project. I stumbled on this thread a few weeks ago and decided to build myself one. So far it’s working great!!!



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[theatrus]

Originally Posted by lighthouze08

Just wanted to thank Theatrus for the work you put into the project. I stumbled on this thread a few weeks ago and decided to build myself one. So far it’s working great!!!



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Glad it worked!

[AZRippster]

Hello,

I was curious if you had made any changes that you confirmed will shorten the on-time pulse of 30ms.

Thanks,

AZRipp

[theatrus]

Originally Posted by AZRippster

Hello,



I was curious if you had made any changes that you confirmed will shorten the on-time pulse of 30ms.



Thanks,



AZRipp

Not to this design. It’s a bit inefficient to have a 555 with such a wide timing gap, so I’d recommend using a microcontroller.

I’m looking at integrating this with a pH circuit to get a full CO2 controller in one up on blueAcro.

[AZRippster]

I'm finding the "On Time" of 30ms is fine, but the rate of the bubbles for my CO2 reactor needs to be slower. The minimum on the potentiometer is still too fast. Is there a different potentiometer value that would allow for even slower release of bubbles?

Thanks!

[theatrus]

Originally Posted by AZRippster

I'm finding the "On Time" of 30ms is fine, but the rate of the bubbles for my CO2 reactor needs to be slower. The minimum on the potentiometer is still too fast. Is there a different potentiometer value that would allow for even slower release of bubbles?



Thanks!

You can use a larger value potentiometer or add series resistance, say 10k, to slow it down further.

[amnesiac]

Theatrus, thanks for posting this!!! I put it together using the BOM and boards and the toughest thing about it was sourcing the Clippard valves. Working for months now without issue and that's saying something since I have ZERO experience working with circuit boards. I do have a question though. My tank is really starting to take off and my calcium reactor is having some trouble keeping the PH down in my CaRX. With the rate cranked as far as it can go I wanted to know if there is some modification I can make to allow for the valve to stay open longer to allow for more CO2. Appreciate the help

Nevermind, I figured it out