Bought some parts, what am I missing? - Page 1
Forum section: electronics / beginners

author: john rock
author_rank: Newbie
timestamp: April 29, 2018, 10:32:49 pm
content: Hi,I want to make a chlorine dispenser for my pool. I bought a small 12V peristaltic pump and a 10a PWM. The pump will take chlorine from a jug and feed it in the pool line somewhere. The PWM is to control the speed of the pump. Hopefully so far so good. I know I need a 12v power source, but not sure what to use. I found a old xbox kinect power supply (output 12v, 10.8A) I thought I could maybe use this to power for tests? I cut the cable and it has 2 small wires and 2 ultra thin wires. Is this a dangerous thing to attempt?Ideally, my power source would be a timer that is wired to my pool 240v timer that controls everything. That way, if my whole pool is "off", the pump won't work. If the pool is "on", then the timer would control the chlorine pump so I doesn't work all the time.What am I missing?Thanks!

author: Eka
author_rank: Regular Contributor
timestamp: April 29, 2018, 11:09:01 pm
content: A sensor to automatically read the chlorine level in the pool, and only add when needed.

author: john rock
author_rank: Newbie
timestamp: April 29, 2018, 11:58:51 pm
content: From what I've read, sensing chlorine in an automated way is quite complicated. For the time being, I'll checking chlorine levels manually, and adjusting the pump timer accordingly. After a while, the proper daily feed should be pretty constant. Worst case, I top up a little manually if needed, but the primary goal is to never let the pool turn green.I'm thinking that the time should be on a dedicated 110v outlet since it needs to keep power at all times to keep the proper time. I could set it to work during normal pool operating hours so the odds of it working when the pool is not are minimal.So should I have a 110v timer that converts to 12v, or a 110v timer in which I plug a 110v to 12v power supply? Not sure where to go from here or what to buy...

author: sokoloff
author_rank: Super Contributor
timestamp: April 30, 2018, 01:45:48 am
content: Quote from: john rock on April 29, 2018, 10:32:49 pmThat seems absurdly higher power than a kinect would need. I'd check the specs on that supply before counting on it to supply 10 Amps of power...

author: Old Printer
author_rank: Frequent Contributor
timestamp: April 30, 2018, 03:17:18 am
content: How much current does the pump draw? I would think a small peristaltic would not draw too much. I would start with that requirement and work from there, maintaining a reasonable margin and let it go at that. This sounds like a good project for a Arduino. You would need to get some mosfets involved to handle the current, but it would, give you a host of options on controlling and monitoring. Would be a neat project you could sink your teeth into.

author: james_s
author_rank: Super Contributor
timestamp: April 30, 2018, 03:34:03 am
content: The power supply is probably for the whole Xbox, that's about right for that. The two small wires are likely for Kelvin sensing, they allow the power supply to compensate for voltage drop in the cable.How much power does the pump draw though? 10A sounds like a HUGE peristaltic pump, usually pumps of that type draw a fraction of an amp, a small 12V "wall wart" might be plenty.

author: Nerull
author_rank: Frequent Contributor
timestamp: April 30, 2018, 04:39:39 am
content: The 360 Kinect has a USB 1.08A power supply, not 10.8A.

author: sokoloff
author_rank: Super Contributor
timestamp: April 30, 2018, 10:28:37 pm
content: Quote from: james_s on April 30, 2018, 03:34:03 amAn Xbox doesn't draw anywhere near the same power asTWO60W incandescent lightbulbs...Quote from: Nerull on April 30, 2018, 04:39:39 amThat seems a lot more reasonable.

author: james_s
author_rank: Super Contributor
timestamp: April 30, 2018, 10:34:30 pm
content: Quote from: sokoloff on April 30, 2018, 10:28:37 pmI have a power supply somewhere from an Xbox 360, it's something like 12.5 Amps so I beg to differ.Here, this is exactly what I havehttps://www.amazon.com/Microsoft-Original-Power-Supply-Adapter/dp/B000PT18OS203 Watts, so more than three 60W bulbs.I was using it for a while to power a LiPo charger for my RC airplanes until I upgraded to a more powerful PSU form a server.

author: sokoloff
author_rank: Super Contributor
timestamp: April 30, 2018, 11:35:59 pm
content: I stand corrected. How hot is the Xbox in operation?

author: james_s
author_rank: Super Contributor
timestamp: May 01, 2018, 12:06:30 am
content: Quite hot as far as I know, they've had problems with BGA soldering failing. I've never had one myself though, I only have the power supply.