Thank God i found you! Irrigation system questions

[Spadez]

Hi guys,

First off im so so glad there is a forum like this on the internet, i was having real trouble finding anywhere that might be able to help me and i have spent many hours waiting for replies on forums that never came. So, let me introduce my project (and problems).

I am going to be making an irrigation system for my a-level project, there is more to it but this is what i am looking at at the moment. My problem is, i have got a circuit that i can use to do what i want but it will take a little modification which i have recently found out is going to be very hard. What it needs to do is turn on at a set time everyday and then turn off after a set time everyday. That’s all it has to do. It would be nice to make it more advance with a count down screen or something like that but its not a must. Now i can either mod this circuit i have just brought or buy a new one that is better suited. Here are the problems with my current circuit:


I have a circuit (see picture below) which has two rows of 10 metal contacts. On top of those contacts sits 2 removable, flexible (presumably conductive) rubber-like bars. On top of that sits a little screen. Here is my problem, it cannot be like this, what i need is a screen that can be wired in because the screen is going to be some distance away from the actual circuit. There are contacts on the circuit that i could solder wires to, but none on screen. My question is, is it possible to get a replacement screen that i can solder in (solder wires on the screen to the solder points on the circuit).

**broken link removed**
(The points at the top are what i am referring to)

**broken link removed**
(Screen pictures with the two bars that sit under it [top and bottom] which takes the charge through to the screen)



-------------------------


**broken link removed**

Using this picture again, in the lower half of the circuit you can see 8 small squares. These are where two contacts meet but not join, they are about 1mm away from each other, they are almost like fingers going into each other but not touching. When you push the switch a contact comes down and covers both sides of the contacts thus completing the circuit. These are so small, is it possible to solder a wire to both sides and attach that to a non locking switch, or is it just too small to be able to do that without messing it up and putting a piece of solder onto both contacts accidentally


There is another problem, but compared to these it is a minor one so i wont worry about that just yet. Any help you can give would be hugely appreciated! Also, if you know of a cheap circuit that can do what i am after can you also redirect me to that, although if i can help it i would rather use what i have already brought because it was quite expensive and i dont want to waste it.

Thanks and regards,

James

 

[Nigel Goodwin]

You can't do anything with the display, best thing is to move it complete with PCB, and run the connections from the PCB to where you want.

 

[Spadez]

Damn ok, so there isnt another screen i can buy that is the same with pins, which i can solder wires to to connect to the pcb. If there isnt thats a royal pain in the ass. Do you know of a pre-built circuit that can do what im after?

 

[zkt_PiratesDen]

Ive read yopur post twice and I still dont know what you need. Sounds like you need a on-off timer .? As far as soldering wires to pads spaced a mm apart- sure can- if youre careful and have a small enough tio on the soldering tool.
zkt

 

[Spadez]

Cool. Ok well what i am looking for is something that would say turn on at 7pm every day, and turn off at 7:20pm...then turn on again at 7pm the next day etc etc.

Im not saying it has to be exactly those times, but it needs to turn on at the same time everyday and turn on several minuets later. It would be nice to have something like a countdown timer on there, but this is just being fancy and it isnt nessesary, just a bonus.

 

[zkt_PiratesDen]

all electronics has an appliance timer that can switch at 30 minute intervals for a few bucks. If you need a smaller interval might try a digital appliance timer. Might cost $20 or$30 thu. I saw on at Lowes building supply

 

[JimB]

Spadez

I am making the tentative assumption that you are in the UK, (your location is not filled in).

Why does the display have to be remote from the board? and how remote?
There appears to be pads for push buttons* to set things on the display so "remote" cant be all that far way.

The purpose of your project is not clear (OK it is an irrigating thing), but does the project have to demonstrate a knowledge of electronics, or is the electronics just incidental?

* OK I have just re-read your post,
You have bought a timer thingy,
I assume it does what you want it to do,
but you want to, or need to re-package it somehow?

As for solddering to the "fingers" and connecting a separate switch, that is no problem, depending on your soldering skills.
Hint: instead of soldering to the contact fingers, follow the circuit board track way from the fingers, carefully scrape away the green solder resist until you get to the copper, then solder your wires there.
That way you dont mess up the fingers in case you have to use the original push button for some reason.

As for the display, the best bodge I can suggest is to make a little circuit board which matches the pattern of the pads for the display. Wire from the original pads to your new circuit board, then clamp the display onto the new circuit board and original rubber strips.
Say a prayer to the electronic smoke god and switch on!

JimB

 

[Oznog]

The glass contact fingers cannot be soldered. At best you could have a piece of PCB with appropriate LCD mounting hardware with the zebra strip connecting them, then running the wires to the real PCB.

But I suspect this may not work. That level of LCD drive is AC, not DC, and very low current. The driver may be so loaded down by the capacitance of the wire lengths that the LCD won't function. Or the crosstalk may mess it up too. LCDs just don't get wired up this way.

 

[Oznog]

I should probably also mention that it appears you are close to "cheating" on this project. It sounds like you're taking an existing product and making superficial changes and submitting it as your project. If this is high school, this may be within expectations, if this is a college or other professional course, it's cheating and not acceptable. You need to design a circuit to learn anything.

There are many text LCD modules out there to play with. You need a microcontroller to write instructions to them. The controller will also be able to perform all the logic and you can implement new features (like detecting the moisture in the soil) quite easily. Microcontrollers are easy to learn and it's crazy how cheap yet powerful they are.

 

[Spadez]

Dont worry about the cheating side, this project is much more involved than this circuit, i will of course be saying in my work that this circuit is pre-made and not something i have made myself. There is sufficient work to allow me to get an A so thats all that matters to me.

I wish i could use a microchips to create the perfect circuit, but i cant because i wouldnt know where to start. I am only really able to create basic circuits or tweak pre-made ones, anything more than that is above me. If anyone is willing to step in with more information i would appreciate it, but i know it would take a while to explain so i understand if nobody does.

 

[Russlk]

As ZKT said, your best bet is to get an appliance timer. You can set the start time and stop time and it repeats every day. I use one on my hot water system and it has been running for 10 years.