timer for livewell pump

Discussion in 'The Projects Forum' started by seabear, Aug 14, 2010.

  1. seabear

    Thread Starter Active Member

    Feb 20, 2009
    34
    0
    Hi all, hope you can help,

    Briefly, I am very capable with circuit construction, but not deep enough to actually design from scratch. I was hoping you could point me to or do a quick-draw simple circuit to control my boat's livewell pump. Its a 12 volt system with on/off switch, but I would love to change it so that I could control a timed operation for keeping bait fresh over night without draining the battery.

    Settings would include:
    Off
    On continuous
    ON/OFF presets or variables (On for 1 to 5 minutes, Off for 10 to 60 minutes)

    Any help would be very appreciated, thanks for your time.
     
  2. whatsthatsmell

    Active Member

    Oct 9, 2009
    102
    4
    Here's a good start:

    http://forum.allaboutcircuits.com/showthread.php?t=2486

    I've built this and it works well. Hook it up to a single pole double throw lighted switch, and you can use your pump in conventional or timer mode, and the light on the switch will work when the pump is on in either mode.
     
  3. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    A simple and cheap industrial timer would be the best solution for you.
     
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Agreed, 555 timer IC is the way to go, it can easily be set up with some driving circuitry such that it powers the pump for 5 minutes out of every hour although when dealing with minnows I'd tend to want 2 minutes every half hour.

    555s don't like short duty cycles so you'd need to use the output as inverted. then again that's no problem as I used a two stage output circuit with a simple NPN driving a 2N3055 so it will handle most any pump current requirements.

    Values and part numbers are easy enough to calculate, or most any of us could do that for you. It could be set up for a specific set of on/off times or one of the resistors could be replaced with a pot so you could vary the amount of on time per cycle. Something like adjustable between 1 - 5 minutes every 30 minutes ought to be just about right thus you can increase it if you've got a lot in there or shorten it if you've only got a few left.

    http://www.innoengr.com/examples/low_DC_timer.jpg
     
  5. seabear

    Thread Starter Active Member

    Feb 20, 2009
    34
    0
    Thanks guys for the responses.. sounds like the one from Marshall would fit my needs the best. I like the idea of some preset on/off times rather thank a pot.. and then I could fine tune it with some different R values. For the next step if you could provide some component identifiers and values I'll get right to it... again I'm not a designer but more of an implementer and tinkerer and good with a soldering iron..
     
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    What duration of on and off times do you want?
     
  7. seabear

    Thread Starter Active Member

    Feb 20, 2009
    34
    0
    For presets I think we should start with the following:

    ON continuous
    OFF continuous

    Pump ON intervals
    - every 10 min
    - every 30 min
    - every 60 min

    Pump DURATION
    - 5 min
    - 2 min

    Open to suggestions.. what do you think?
     
  8. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Well, to have that many choices for the variable times you'd need switches whereas using at least one pot would make it easier. Let me think about it for a bit. I don't suppose precision is all that important?
     
  9. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    There are three components involved in determining the timing and duty cycle of these things, I think using two timers is going to work better and a 556 dual is only pennies more than a 555 single. Getting there, slowly. I'll figure out the values and re-draw he circuit.
     
  10. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    I'm sure the experts and the microcontroller guys had this figured out hours ago but I've got something I like. I just need to assign some values to it and supply part #s.
     
  11. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Anyone want to look this over to catch any mistakes? Obviously I haven't tested it.

    I went ahead and drew it with two separate 555 timers, probably better to split them up since the second one will be sourcing a fair amount of current to drive the power transistor.

    I've also attached a parts list with exact Mouser part #s, ( http://www.mouser.com ) they're as cheap as anyone, super fast and only charge actual UPS shipping at their discounted corporate rate so it'll probably cost about $4 to ship.

    After some thought about using rotary switches and other things I just went ahead with mini toggle switches. You would be able to find these cheaper elsewhere but these are good switches rated at 5A.

    You also get the bonus of having several more time options, the values are additive as you switch on more switches.

    K1, 2 & 3 set the on interval and K4 & 5 set the run time per interval.

    In other words if you just switch on K1 you'll get around 1 hour, K2 only equates to 28 minutes, K3 to around 10 minutes. K1 + K2 = 1-1/2 hours, K1 + K3 = 1 hour, 10 minutes etc. Same applies to the others:

    K4 = 5 minutes, K5 = 2 minutes, both on would give you 90 seconds. The power transistor comes in a plastic case so it won't need an insulator but it will need heat sink compound and some way to dissipate the heat generated. If you choose a thick die-cast aluminum box it should handle it, if you choose thin metal or plastic one a decent size heat sink will have to be added. I prefer the cast ones anyway as they're far more durable and easy to seal. They are also available with mounting flanges and my personal choice would be a 546-1590TF

    The circuit should be good to drive at least 3A worth of 12V motor which I assumed would be plenty for a simple aerator pump. If it needs more current we'll probably want to add a driver transistor in there as I'm close to the maximum driving capability of the 555 IC if the transistor gain comes in at the absoulute minimum. Chances are it'll do 6A with no problem but when you're breadboarding something trying to replace a failed part can be a hassle.

    http://www.innoengr.com/examples/aerator_timer.jpg
    http://www.innoengr.com/examples/aerator_timer.xls

    In essence, when the circuit is powered up the output of the 555 goes high and triggers the second one through C6 which will run the motor for the selected time then turn it back off. As the first timer continues timing it will go into a low output state for a while then when the full amount of time has elapsed it again switches its output high and that pulses the second one into its timing cycle again.

    Switch K6 turns everything on or off, and K7 is a manual on switch which, if on, allows the motor to run all the time ignoring the timer circuit.

    Parts can of course be substituted, a 25V or 35V electrolytic will take the place of a 16V one but they're larger and more expensive. As always I do recommend using high temperature rated electrolytics, they tend to last about 10 times as long as the regular ones and only cost pennies more. Likewise the .01 uF caps can be ceramic or of a higher voltage, they're non-critical in their applications here. The values were carefully chosen to get as close to your desired times as possible using standard off the shelf values, and the part #s I used in the BOM were the least expensive options that were shown to be in stock at the time I chose them. I know you can find multitudes of less expensive 555 timer ICs but I tend to specify TI because #1 - never got a bad one and #2 - when they claim a 200 mA output capability you know you're going to get it. I've accidentally overdriven them by quite a bit a few times and they never complained.

    Let's get some comments from the timer experts before you go off ordering parts, I'm half asleep and may have made a mistake or two.

    I didn't add a fuse, a power indicator or one that lights up when the motor is actually running but either or both could easily be added.

    When not running the motor (sitting in the middle of a timing period) the circuit only draws about 20 or so mA from the 12V supply, about the same as a single LED would.
     
    Last edited: Aug 16, 2010
  12. seabear

    Thread Starter Active Member

    Feb 20, 2009
    34
    0
    This is Great!! I can't wait to try it out. Thanks so much for your help. I'll keep watching for updates or mods. And when I get it built I'll let you know how its going.
     
  13. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Nobody's found any faults yet or at least they haven't been brave enough to comment. Let's give them some more time just to be sure.

    This may also be a circuit best built on an etched PC board. I can generate an exact sized pattern for that too given time but it really can be a hassle trying to etch one and it adds to the cost over simply using perfboard and any minor mistakes are more easily corected if using perfboard. Mouser has a nice perfboard in FR1 glass-epoxy that would handle it, Radio Shack also has one that would work but it's their cheap phenolic material that isn't as forgiving nor as easy to work with. I've got a video somewhere about how to build on perfboard, dont know if it's actually instuctional or not as I haven't watched it.

    Simple enough circuit that could find alterate uses. The motor could be replaced with a relay and used to drive about anything.
     
  14. seabear

    Thread Starter Active Member

    Feb 20, 2009
    34
    0
    Thats one of the things I was wondering about, if we drove a relay instead of using a power transistor, then could we just tap into the existing line which is already fused?
     
  15. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Woudn't matter, relay or transistor, if the existing line is fused then you're covered.

    Take the fused + line that normally went to the aerator and use it to suoly the circuit.

    I'm assuming the pump is directly driven by a fused line and, if it's already switched, you won't need K6 that's shown in the circuit.
     
  16. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    I'm thinking we can easily fit all the active circuitry on this board:

    http://www.busboard.us/pdfs/BPS-MAR-SB400-001.pdf
    (mouser part # 854-SB400)

    and by trimming a little of the length off the board it will fit in here with room to spare:

    http://www.hammondmfg.com/pdf/1590TF.pdf
    (Mouser part # 546-1590TF)

    Supply and feed wire could be common automotive #16 AWG stranded or any other medium size stranded wire you have access to fed through the appropriate size of one of these with a dab of silicone seal for the fun of it:
    http://www.mouser.com/catalog/catalogUSD/642/1896.pdf

    and heat sink compound is about as cheap at a local PC store is it is to order it.

    When I've built small runs of products around this size I've just hand sketched up what I wanted for the faceplate and had Kinko's design, print and cut one from self-adhesive vinyl, but they've got a 1 ft*sq minimum so you could print several of the same thing in case one got messed up or you had to build another one for a friend. Alternately, if you're not striving for perfection, you can just use one of those label printers or even do it in Sharpie pens but we have to remember that, while not immersed, it will occasionally be exposed to the outside elements so Sharpie pens aren't the best choice. If you do want to add an LED I'd just use one + the appropriate resisitor across the motor so it only comes on when the pump is running. Thousands of choices here but really only two mounts that I like - then again you may be able to hear your pump well enough not to need one.
     
    Last edited: Aug 16, 2010
    seabear likes this.
  17. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Haven't seen a single complaint of error or any alternate suggestions yet, I'd say it's a go.

    Create a Mouser acount (they won't require a payment method until you actually place an order) then use their BOM import tool to enter the order. It's hard to find buried in their web interface but it's there, I think the only columns you need to copy from that spreadsheet I created are part # and quantity, one set per line, then it automatically generates a viewable order you can check against. When you're happy with it save it as a project file then hit he "Order Project" button leaving 1 as the quantity.

    Have some good 60/40 solder and an= low-mid wattage iron around, plan out the most logical parts layout by hand then go at it slowly.

    I still don't like lead free or water clean flux solder; I don't think either do as good of a job. Regular flux cleans up fine with rubbibng alcohol and a toothbrush.

    This may also be a personal preference but I don't like Ersin solder, of all the brands and sizes I've tried I've found this Kester to be the best all-around choice for most anything except the very large or SMD connections. It was 0.032" but I see they've gone metric now:

    Mouser p/n 533-24-6040-27 - 60/40 ELECT ROSIN CORE SOLDER .031 DIA

    A 1 pound roll of this and a Weller WLC100 iron set at about 3-1/2 will last you almost a lifetime. Solder is expensive no matter where you buy it but the irons vary in price quite a bit by supplier. If you can find them locally it will save some on shipping but Amazon has the free shiping deal on the irons for $46.50 total. You can get by with something cheaper if you never expect to build again but the hobby is highly addictive, next thing you know you'll want to build a temp at depth meter and a fish locator, boat spedometer or who knows?

    How long have I had the two I own in use? 17 years each. How many times have I replaced the tips? Once, on just one of them and only because it got bent.
     
    Last edited: Aug 19, 2010
  18. MMcLaren

    Well-Known Member

    Feb 14, 2010
    759
    116
    Hi Marshall (and gang),

    I've actually thought of a few microcontroller based solutions these last few days but I didn't want to detract from your help, guidance, effort, and solution. On the other hand I thought the OP and other Forum members might appreciate being made aware of a relatively simple and elegant alternative microcontroller based solution.
    [​IMG]

    The only real advantage is probably functionality. The disadvantages are, (1) you would need a 5v regulator, (2) the 12F617 at $1.09 is more expensive than a '556 IC, (3) you would need a simple program, (4) you would need someone to "burn" the program into the microcontroller.

    The program is almost a "no brainer" for many of the programmers on the Forum. I could probably write it and test it in a couple of hours if this is a "one off" project and not a commercial venture. Finding someone in the OP's local area who might be willing to "burn" the program into the microcontroller for him is another matter (which might be a lot easier if the OP would add location info' to his Forum profile).

    Cheerful regards, Mike
     
    Last edited: Aug 20, 2010
  19. seabear

    Thread Starter Active Member

    Feb 20, 2009
    34
    0
    Interesting approach, but maybe more elegant than I need. I'm in the middle of trying the first design as submitted by Marshall... so far no luck as the output stays high continuously no matter what switch settings I use. Could it be because I tried to use a dual 555 12 pin chip instead of two individuals??

    As a side note I came across some info on PICAXE programmable chips that could maybe do the same thing and the programming software is free and only takes a USB cable to burn the chip. Anyone have any feedback on that one?
     
  20. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    A dual 555 (aka 556) is a 14 pin IC and the pin numbers are different. I kept them separate as it's oten easier to build with them that way.

    It can be done either way but you'll need to print the circuit and clearly lable the pin #s so you keep the two separate. On a first project it's also easy to confuse pin #s because you're wiring from the botom and they're numbered from a top view.
     
    Last edited: Aug 20, 2010
Loading...