Fixing or Replacing my digital hose timer.

I loved this little hose timer last season. The interface is so simple, and if you know what a microprocessor is trying to do, easy to understand. Just set both switches to off/reset, wait for the led to flash, switch to what you want, led flashes again, and begins the new program.

If it had kept working, and not become unreliable, I don't think I would have messed with it.

It has trouble making water flow (little "grr" sounds) and so I opened it up. I was surprised to see a simple analog drive. A gear motor driving a ball valve, which has a detent for a simple switch. To turn on or off water flow, the microprocessor just drives the analog motor until the switch changes state. All this on two AAA batteries.

It works without load, dry, now, but seems to be overcome with friction when wet or under pressure.

I know sprinkler timers are a well explored area for hobbyists, and so I have a couple quick questions:

Do you think I can get it working by putting in say a relay, and driving the motor harder? (I'm a programmer and not totally sure what I mean here, at a bit higher voltage, 5v?)

Or are such analog and gear train systems right out in terms of reliability? Must I go with a solenoid?

(I ask here because "plan b" is to go with a solenoid and an Arduino)

I am also interested in making one programmer for watering plants, istead of buying one as above.
Using an arduino will make it easy to reprogram and easy to be repared or change spares.

I intend to utilise a solenoid valve (1'' or 3/4 tap / 12-24volt / 1-12bar) driven by an external relay.
I do not want to use a pump and a humidity sensor, as shown in so many examples no the internet. Instead I Prefer the "time & frequency" way

I am having difficulty in understanding how to make the programming for the below.

I need to have selections:

  • one for the watering time (OFF, 1min, 2min, 3min, 4min, 5min, 10min) and
  • one for the frequency (6hr, 12hr, 24hr, 48hr, 72hr)

Is there a need for an "RTC module" for the frequency or programming can be performed with delay function

Thank a lot

I don't believe my simple timer above knows the real time, it just uses "time from program change." That is, when I go from reset/off to 4hours/1min it will then run for the first time in 4 hours from my change.

Maybe this is why normal consumers find a display-less 1-led system confusing.

Anyway, I think the switches are just common "Rotary Switch - 10 Position" but probably not connected to 20 digital pins? This is where I am not an engineer again. Not sure if you'd hook the 2-10 position switches to a multiplexer circuit or some kind of resistor network to be read as an analog value...

So, if you are comfortable with a "from reset" time, no you don't need an RTC

Do you think I can get it working by putting in say a relay, and driving the motor harder? (I'm a programmer and not totally sure what I mean here, at a bit higher voltage, 5v?)

There probably is already a relay and I have to assume it's a mechanical friction problem. I'd try some lubrication on the gearmotor and everything mechanical that moves.

If it's corrosion in the gears/bearings or something plastic has warped, there may not be much you can do.

Thanks Doug,

I've been reluctant to take out the last screw on the ball valve, because I'm not sure how they got it in there ;-), but that's probably what I'll have to try.

I am having difficulty in understanding how to make the programming for the below.

I need to have selections:

  • one for the watering time (OFF, 1min, 2min, 3min, 4min, 5min, 10min) and
  • one for the frequency (6hr, 12hr, 24hr, 48hr, 72hr)

The programming depends on the hardware & user interface... Start by designing the user interface and program accordingly.

A real time clock and LCD display for the time would make a DYI timer uneconomical unless you want some feature that doesn't exist in a mass-produced product. (Your porject doesn't have to be economical or practical, but that may be a consideration.)

Here's one solution: One pushbutton for frequency and several LEDs... One LED for each frequency. Every time you press the button the next frequency LED comes-on and the frequency is selected, and it cycles-around.

A 2nd button and a 2nd set of LEDs for duration.

Or just two LEDs that for example blinks once to indicate 6 hours, blinks twice to indicate 12 hours, etc.

You can use delay() but your program will "freeze up" during delay, so it can't respond to user input. Look at the Blink Without Delay example for doing time-related things without pausing your program.

Thanks so much for the answer.
I was actualy thinking to avoid this led examples, in order to achieve longer battery life,
apart from that it is a very nice idea!

Nevertheless, I would like to do something simpler,
similar to the Claber programmer: “Aquauno Select 8432”
and use only two multiposition switches.
Are there any ideas on this concept?

I suppose I chould use “If…else” functions or “switch case”.
Is there any easier way to do this?

Finally if there is any similar project that someone would like to share, that would be great.
Thanks a lot

p.s. Is it possible to set a delay for two days in milliseconds???
or is there an other way around this?

I am thinking of using pcb mountable DIP multi switch (x6 switches)

Depending on the number of switches turnen on a number of minutes will be defined.
No1= 1 min
No2= 2 min
No3= 3 min
Np4= 4 min
No5= 5 min
No6= 10 min

Lets say I turn on No1 & No6, the result shoul be 1min+10min = 11min of watering.
If all are turned on watering time would be: 1+2+3+4+5+10=25min

I am not sure if this is easy to do.
Will I need resistances and one arduino input or shall I use different arduino inputs per switch without using resistances.

I thought I should add a follow up and declare the surprising solution. It turns out that Harbor Freight batteries (which if you read the fine print say "zinc chloride ... low drain devices") are not suitable for this timer. I tried some Sony batteries I had on hand ("carbon zinc ... heavy duty") and all seems well.

Maybe surprising to me because I'm new at this electricity stuff.

Well, that's good to know why those discount batteries cost $5 for 50 but other stores can still make a profit selling 4 batteries for $10.