Backyard Aquaponics
A place to discuss aquaponics

All right. I know many people out there are interested in repeat cycle timers. I also know that to by a ready made repeat cycle timer is usually way over priced (between 60 and a few hundred dollars depending on type etc.) However, I also know that the parts to build one yourself if you are into DIY electronics stuff are not so costly though some tinkering and experimenting might be needed to get the cycle times one wants.

Unfortunately, I'm not a circuits and electronics guru. I really only know enough to do some basic signal flow and have a high school level basic electronics education. I have been searching for some instruction/diagrams for making such timers as I have read in many places that it is relatively simple. Sadly the only instructions I have really found are garbled or have tables and diagrams missing and don't actually relate all the info in words, just says refer to diagram or table

Sigh. So please, any of your controls or electronics gurus. If you are willing......... Please share some resources on this subject.

I have some parts coming and will be attempting to put together a small prototype for myself. For my purposes, I want to do 10 seconds on and 15 minutes off. Many other people might want to do a few-15 minutes on and 45-60 minutes off.

I expect the basic parts to build a timer probably cost under $10 if one were to know what they were doing. For some one like me needing to get bread boards and jumper kits as well as extra parts since I'm not sure exactly what I'm doing It will probably cost me more like $35 with shipping.

If I manage to figure it out, I will share info.

Hi TCL
If i get a minute i`ll have a play and see if i can get anywhere near to your timings. The tolerance of the components add up so its difficult to make two exactly the same. I guess a few seconds +/- would be good enough? $35?...more likely $10 or less

Hi TCL,

I would use a pic micro and opto couple a relay or triac, the pic micro is about $2 and I would be happy to program it for you if required. If you need its timing adjustable with a LCD display then costs go up a bit.

Maybe we could create a public domain adjustable timer so others can benefit.

notice the $35 was for me trying to find the parts when I'm trying to go shopping with an incomplete list.

Yea, a few seconds either way are not that big a deal. I was thinking to try using pots instead of fixed resistors to be able to adjust the times.

I agree, if one knows what parts to get, where to get them, and how to use them, under $10 easy.

Yep, that is what I'm talking about!!!!

How fast do you need yours TCL? If we do a general design we probably need to set up a thread and survey needs a bit. For your current situation it might be quicker to just do that timer, then do the general one next.

I believe there are others on the forum with more electronics and robotics experience than me if they are also willing to pitch in I am sure we could do something worthwhile.

When I get a chance I will post the details of my sequential timers.

This seems as good a thread as any to look for info though ya might need to start a new thread if you want to run a poll.

Hopefully any that are good with electronics will pitch in here and share.

I'm planning to barrel right on through with the parts I already have coming and attempt to build something as I kinda need it last week (I'm actually manually going out and opening/closing valves to make things function at the moment.)

Even if we come up with a good DIY set of instructions and parts lists for some basic cycle timers for people who wish to try to build their own, I don't think we will be robbing too many people of business selling nice packaged cycle timers since most people don't want to build their own.

Now I expect that the average person who just wants to cycle the pump on and off for a standard system, will want a cycle timer that can do on times between 3 and 15 minutes and off times between 45 and 60 minutes. I believe I already mentioned this though.

I'm still going for something I can use to give a momentary or short on time (which I can then hopefully use to trigger something that will close a valve for 10 seconds or so) and an off time between 10 and 30 minutes.
And hopefully I can make mine to be somewhat adjustable.

I had mentioned on some other thread that I wanted to design a timer with a small AVR processor. The goes would be to make it have a serial interface (no buttons to get wet and break) so the times could get adjusted. I could also use one of interrupt pins to attach to a flow sensor on the drain to turn off the "on" cycle to help reduce power consumption on the pump.

I'm debating using a latching relay to help reduce the power consumption so it could run on batteries. If I used a standard relay, it would consume more power....and probably would need a small power supply to run. The RS232 chip will ad a little cost, but can make it easier set accurate times.

I'm currently working on a another controller project, but will try to sneak this one on in the next couple of months.....

If anyone has any design suggestions, speak up!

From Sequenced Growbed Fill - Is it a Holy Grail of Aquaponics?


see LM555.pdf for more details

There are two ways to make this a Repeat cycle timer.
the first is to do some fancy math and selection of components to get a continuous waveform, but imho, this is just too hard.
the second is to use the diagram as above, but make two timers, one that can be tuned for on time the other for off time.

Of course if you want to get micros, the timing will be more accurate, and not change with temperature and other outside elements, but it will also be much more complex.

Just having a thought now... we could use one simple timer, set it to 50% duty cycle (one of the photo as shown above) then put it's output into a counter. Using two dipswitches we could set the number of timer cycles for on time then the number for off time.

Let me draw soemthing...

Maybe something along the lines of this : http://www.jaycar.com.au/productView.asp?ID=KC5464

Low Cost Programmable Interval Timer

Ref: Silicon Chip Magazine June 2008
Here's a new and completely updated version of a very popular project: an easily programmed low cost electronic timer. It operates from 12VDC, with low current drain: <50mA when relay is on, <5mA when relay is off. It is link programmed for either a single ON timing period, or continuous ON/OFF cycling and can be link programmed for any of 48 different time periods, separately for ON time and OFF time. Selectable periods are 1/2/3/4/5/6/7/8/10/20/30/40/50/60/70/80 seconds, minutes and hours. It may be restarted at any time simply by pressing reset pushbutton. Kit includes PCB and all specified electronic components.

QTY
1+ $34.95
5+ $31.45



Scott

Just for clarification, you want a design for plug-in AC right? In the US, that'll be 120 V, 60 Hz. I imagine Aussie uses the European system, 240 V, 50 Hz?

This would help solve the problem of long time cycles, 555's are not much good over about 8-9min.

My preference for pics is less components, low cost, more flexible, easily reprogrammed and can sense conditions.

I had not noticed this one but you are right I think it could do the job. Does anyone have the article its based on?

from http://hobby_elec.piclist.com/e_ckt5.htm



This is a 555 oscillator.
the output will go high every 1.44/((Ra+2Rb) x C) seconds.
So pick your resisters, or replace them with pots and you can have a nice timer.
However this is not so nice, as 10 seconds off and 10 Minutes on are MUCH different and we will either lack recision or range to achieve this.

So how about this then:


I think it could be done for about $20, and less if one were to try getting 'Samples' from many of the chip manufacturers

As usual Jaycar put up a nice blurb that gives you only 50% of the info, it's quite a tease and very frustrating.

What is the duty cycle of this wonderful timer?
It does not say if the on time can be different to the off time.
Also, WTF does "be link programmed" mean?