Electronic autodosing timer - figured it out

[Wasserpest]

Besides adjusting the volume and concentration of solutions, controlling the duration of the dosing is a neat way to adjust how much is dosed. For larger tanks or dilute solutions, electronic timers with minute precision are usually precise enough. For smaller tanks, and concentrated liquids, shorter, adjustable dosing duration would be beneficial.

Also, it would be neat to find some electronics gadget that can be connected to the light timer, so that whenever the light turns on, fertilizers are dosed.

In my quest to find a solution I came across this little electronics kit. I asked someone a specific question wrt suitability for my purposes, and they told me it would work. Unfortunately, this isn't the case.

The kit works by closing a power switch, and when opening it, it will time a couple of seconds and then interrupt power to the equipment that you want to control. Not too useful for this autodosing application.


To make this work, I would need some sort of relay switch that works with 110V, and switches between two pairs of contacts. When the lights are off (no power to relay), the switch of the MX046 would be closed, as displayed in the little picture. When the timer switch turns on, the relay would switch: open the MX046 switch, and turn on the pump, which then runs for the programmed number of seconds and turns off.

Any ideas what kind of relay I could use for that?
Better than a relay (which would draw constant power for long periods) would be some electronic flip flop switch that changes state each time power is applied. That would probably mean dosing every other day... not a problem though.

Anyway, any help, thoughts, comments that don't blow the budget (no X10 or Aquacontrollers) will be appreciated.

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[fishscale]

That's a really neat idea, too bad I can't help you with it.

[jbolinger]

Do a web search for NE555. Google just gave me 332,000 hits on it.

This is a little 8 pin integrated circuit that can be wired to do various timer functions. It should work for you. That is, if I understand what it is you are trying to do.

If you have even basic knowledge of how to wire a circuit you should be able to make use of this. The timing is controlled by a capacitor and one or two resistors. The resistors could be made variable or switchable for adjustment purposes. If you need to control a valve or pump you will probably also need a transistor. This device works on DC so you will also need a power supply. A wall wart would do.

There is also a dual version in a 14 pin (or is it 16?) package, but I do not recall the number---its been a LONG time since I did any work like this.

Jim

[Wasserpest]

Thanks for the tips Jim. If I understand correctly, the NE555 timer and the mx046 delay switch can do somewhat similar things. No doubt one could create a good solution, but rather than starting from scratch with the NE555, I am looking for a way to make the MX046 to work for my application.

So I am more interested in something to switch between the power switch and the pump circuit.

[Johnnnn_h]

What You want is called an interval timer, If you go to pg #870 in here http://www.mcmaster.com/

In the "About Relays with Timing Function"

Interval,, Pluged into lighting timer, when it sees power it sends the power on for desired time, and thain drops power.

Switch-On Initiated Interval ,,, Basicly needs power and gets plugged in to constant power, and needs another plug from the lighting timer for a trigger, thain the timer stars counting, and thain drops power.

The second one needs to be plugged in.

The ones on the page are pretty heavy duty cycle wise 10 million cycles.

[Wasserpest]

That's great stuff, thanks for the link. Unfortunately out of my desired budget.

Looks like I need to return those cute little kits.

[crazy loaches]

If I understand this correctly it sounds like an easy solution. Your circuit just creates a short pulse, triggered by a switch correct? And your looking for something to act as a switch that will be pressed daily or every other day right? If that is the case then just use a regular ol timer hooked to a relay. Set the timer to whatever your dosing time is. Only difference is it will hold your switch down for a whole minute, but your circuit then only runs for a few seconds. This sounds to easy so I am guessing I might be missing something...

[swylie]

Originally Posted by crazy loaches

This sounds to easy so I am guessing I might be missing something...

Yeah. The McMaster relays that would work in combo with a standard timer are very expensive.

[gmccreedy]

Wass,

I understand you intent, but not sure if you are going to find something that is resonalby priced that will do what you ask.

Why not dose solution per time as opposed to dosing at a set time for a dilluted solution. Are you setting up one dosing solution for mutliple tanks (of different sizes) to draw from?? Is that why you are going this route?

[gmccreedy]

O... But there is always the X10 route too...

http://www.x10.com/products4/overtur...on_ps_nox.html

[crazy loaches]

Originally Posted by swylie

Yeah. The McMaster relays that would work in combo with a standard timer are very expensive.

McMaster relays? Just get some cheap relays, shouldnt be more than a few bucks. If you have lvdc relays then just plug a cheap wall wort in the timer.

[tazcrash69]

Originally Posted by gmccreedy

O... But there is always the X10 route too...

http://www.x10.com/products4/overtur...on_ps_nox.html

That usually doesn't fit into Wasser's Cheap auto anything.

[Wasserpest]

Originally Posted by crazy loaches

If I understand this correctly it sounds like an easy solution. Your circuit just creates a short pulse, triggered by a switch correct? And your looking for something to act as a switch that will be pressed daily or every other day right? If that is the case then just use a regular ol timer hooked to a relay. Set the timer to whatever your dosing time is. Only difference is it will hold your switch down for a whole minute, but your circuit then only runs for a few seconds. This sounds to easy so I am guessing I might be missing something...

Here is how the delay timer works: There is 1) Power in (which would always be connected, 2) Power out (connected to the device that is to be switched) and 3) a power switch circuit.

When the power switch circuit is closed, the connected device is powered on. When the power switch circuit is opened, the connected device runs for a pre-programmed time and is then turned off.

So the "regular ol timer hooked to a relay" wouldn't work because it would dose for the full duration of the minute PLUS the few seconds after it is switched off.

I would need a specific relay which does two things at once: Opens the switch circuit, and closes the device circuit. I am thinking there might be cheap relays that do that sort of thing. Just not sure where to get them.