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Forum Index : Electronics : 12v Dc timer module SILCON CHIP MAG
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Lapsy Senior Member  Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Hi all! Recently joined the site to source some information that may lurk in someones back shed! Basically, I want an article from silicon chip magazine, Issue 217, October 2006. There is an article about modding an Arlec 240v mains timer to Dc 12v. If possible, any chance of having a read or palming of a scan for reference off someone? 12v timers seem scarce. Modding a 24hr digital arlec would be great for outdoor solar irrigation use as dc timers I have seen have unusual presets and are not 24hr rotating. For the record, I am attempting to build a small solar irrigation setup for a rural property. The timer is my current soldering mod. Unsure if the article will serve the purpose, from wat I have seen my arlec timer is different to the one they use in Silicon chip. I am banking on the fact the internals are the same. This timer is being recycled. Used to be for a fish tank, until one day I slid the sofa accross the room and it knocked the timer in the wall and bent the socket prongs. Has also had the internal battery replaced, so I am now familiar with its insides. Have resoldered some broken cables and recently given it another revival. This thing is beginning to have some sentimental value due to the history its been through! All help appreciated. Im ok with a soldering iron, but no electronics wizzkid. Highly interested in the silicon chip article so I can recycle this ancient beast that has served me well. Once I get past this stage I may ask or further help with charging batteries via solar, and what the deal is when things are being used whilst on charge. Thanks! This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
For the record, and further info... I saw the article here.... http://www.siliconchip.com.au/cms/A_107706/article.html If you look at their mod, the timer is different to mine, which is.... http://www.google.com.au/m/search?site=images&source=mog&hl= en&gl=au&q=arlec%20pc787&sa=N#i=1 Hoping it is just the plastic housing they have changed and the internals are the same. Also, after ripping the battery out and putting a multimeter over it, the coin battery boots out 1.2v I want to change this battery to a NmHi single AA ( the original coin cell I replaced with another coin cell but this one is NmHi). So if the internal battery goes ghost, I could just recharge the AA in a charger, or alternatly charge it if there is not enough constant power to keep it charged from runtime alone. I should state the same info another bloke mentioned in the forum, about how he would rather spend $6-8 on componnets rather than fork out for the article. In my case, using a differnt arlec timer to what they have modded may render my purchase useless! Any insight appreciated. ( Would be happy to purchase the article/issue if I could be 100% certain it has the info I need ) Cheers! This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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yahoo2 Guru  Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
If you need an irrigation timer and have no power you cant go past the 7000 series from galcon. Fully programable timer with inbuilt soleniod and fittings, all run from a 9V alkaline battery. Only need a filter in front of it. If you live somewhere hot and dry its the difference between plants thriving or dying! yahoo I'm confused, no wait... maybe I'm not... |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Originally looked at the Neta electronic pot plant water system for up to 10 pots. http://m.bunnings.com.au/OurRange/Search/neta%20electronic%2 0pot%20plant/Electronic-Pot-Plant-Watering-Kit/2423 Runs completly off AA batteries for$50 pretty good. However, 10 pots is insufficient, as we are interested in running plumbers pipe in an aquaponics setup (Kind of an adapted NFT system but have stolen ideas from different systems) as we think we could have around 20-30 plants per pipe depending on the type of plant E.G. Basil or chilli. All we need is either a constant flow of water, or we are thinking maybe flooding the pipe at intervals with a slow drain from a fish pond. Main thing is we don't want a pump and timer per pipe. Would prefer running something that is expandable. Cost is a factor, and being slightly environmntal, solar would be great and recycling old components is a good thing, as well as actually knowing how it works so it can be maintained. Some things may seem broken, but they are sometimes salvagable for working components. Put it this way, I have fixed the timer and had it running off mains power. Its just the way I kind of hotwire repaired it that makes it unsuitable/safe for the home, as I am now unable to enclose it back in its housing, due to my repair methods (extended wiring, resoldered areas e.c.t. This things still alive and kicking regardless of its open housing, its just two small circuit boards basically). Hoping if I get this going we could have multipul pumps running from one timer. Jaycar sell a kit for $20 which I contemplated with a 555 timer, but hey, this Arlec is already soldered up! Most of the hard works already done! Another point is... this will get left outside. If someone attempts to steal it, I would like them to be inconvenienced from immediate use, or think twice about wat they might do with it. Have also thought about using 110v pumps just to be a pain, but not had any luck with cheap inverters and seems the long way around in my opinion. 12v is there ready to go... This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Another reason 12v is a more flexible option for me, I've seen a USA seller on ebay, who has a 12v solenoid valve, which can be used on a gravity fed system. Most solenoids need pressure to assist, which is no good for running E.G a rainwater tank system. Have thought about this also, and you could possibly run a flow from a fish pond, into say a bucket or tank (imagine a waterfall effect but the fall back into the pond is from a small tank or bucket). From this side tank you could have a secondary access tap to E.G take samples, run off to plants on a timer, eject dirty water/replace with fresh water for the fish. This also would take some wear and tear out of the system by eliminating a second pump, as a gravity fed valve would replace this. As long as things flow downhill at some point this is another option rather than having extra pumps. This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| grub Senior Member Joined: 27/11/2007 Location: AustraliaPosts: 169 |
The early F&P washing machines used 12v inlet solenoids. You should get the HOT solenoid as the cold were variable opening. |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Grub! Please explain further if you have more knowledge on washing machines! If only you said Maytag! I have one that is in need of repair or maybe past its best. Wondering if I could locate one of these on this old washing machine...? Then again it is about 15 years old so.... maybe not, as it could be very thrashed out, but maybe worth a look if its not a headache to get to. Good idea for sure, definatly like the idea of salvaging a washing machine as the motors tend to burn out. Not many would think of how valuable the valve could be in a certain scenario. This is my point people! Being resouceful is good all round, unless the part is generally past its best and well worn out. I am attempting to NOT contribute e-waste to Ghana, especially when my local council claim the stuff gets recycled within Australia. Those who have not seen where your so called "recycled" electronic goods end up, should google - Ghana e-waste. Youtube videos alongside for proof... fairly shocking. Not to mention some of the computers still have the hard drive in them with information UNDELETED! Shows the locals going through them archiving the info (like credit card payments!)... Anyways, when you have watched that, let's get back to Arlec timers and water valves! Nice one Grub! Top suggestion! If you have any more ideas, throw them out there... Cheers! This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Lapsy, I modified 2 digital timers to run on DC. One is a HPM, the other an Arlec. They both run the internals on 24V DC which is derived from 240V AC with a very lossy cap/ resistor arrangement. These timers use about 30 times less running power when fed directly from DC BTW. Now, in my case 24V DC was perfect as my solar set up is also a 24V battery bank. If you want to run the timer from 12V DC then a cheap DC- DC up converter will do the trick. These are found on E-bay. Oh, the mod is very simple, just remove *everything* that is connected to the 240V plug, including the corresponding socket so no one can plug 240V stuff in. It may help to trace the simple circuit to see what parts need to be removed and where to connect the 24V DC. The relay coil operates on 24V DC and you can use it to switch DC by soldering wires to the PCB where the AC socket was wired to. Klaus |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Nice one Tinker! Cheers! A bloke on youtube showed what your are explaining, but never went into detail on the circuit stuff. He breifly mentioned a pump alone was not enough draw to kick the timer over or something. He had to plug a pump and an air pump to draw enough juice he recons. Unsure if he was using 12 or 24 volt so I might have to have another look. From what you are saying, I just bascally need 2x12v batts, or a 24v battery to kick this over? If so, that's no problem I am yet to invest in the battery so, cheers for the heads up. Wondering if photos can be posted in this forum? Or should I just supply a link for whoever's interested in looking at the circuit board? Maybe Tinker could point out where the mod should be attacked? Just to be sure the internals are looking simmilar. Socket is easy dismantled, I can see how the electricity travels on its path through the boards. Just wanting someone to ultra confim any necessary parts removal (if any) before I start. I think I will throw a photo up next just to check its not got anything different or unusual. I always wondered about the drain from a dc timer as some have no battery backup, so there is obviously power usage just on standby, which is using power daily, even when the pumps are inactive. The fear a span of cloudy weather and lack of charge via solar is a concern on an expanded system, but don't think a pump or 2 running a few minutes a day is going to be an issue with this timer now you mention its power use is lower than other dc timers. Sounds good! This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Lapsy, can you enlighten me what you mean by "not enough draw to kick the timer over"? Just apply 24V DC to the modified timer and it runs, no need to "kick" it. You can see the timers on the wall (right side of pic) here:timers Scroll down to the last message on page 1. I do have the traced circuits somewhere but to be useful you need to confirm that your timer is the same and you can interpret electric schematics. I can't take the timers apart now to take pics of the mod as they are in use 24/7. You can post pictures here easily, just click the second last box under the word "Colour" in the reply header and follow the instructions. You may have to resize your pictures. I did measure the standby power draw of an unmodified digital timer and it came to around 50KWh if its left plugged in for a year. From memory (the exact figures are in the shed somewhere) this reduces to 1.5KWh per year when the timer runs on 24V. Klaus |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
No worries mate! I will dig up this particular youtube video where I first heard the timer was modified. Think the bloke was explaining basically the same as you stated (Think I just didnt explain it greatly). Basically I ran 12v through the timer and nothing happens. So running 24 V it will kick over and obviously 12v pump ends up getting a double dose of power so I gather he added the air pump, which would have been 12v also, so 2 X 12v devices is what he must have been getting at. He does not explain this in great detail, but since you mentioned 24v, I just put 2 & 2 together. I will have to dig around on youtube it has been a while since I watched it... Secondly, here is the internals of an Arlec PC787 timer (If I uploaded it correctly!). Please excuse the camera flash, it makes the actual pcb look dull & sketchy. It is actually a very clean board for its age, but the flash makes it look a bit cruddy... 
The battery clip in the pic I soldered in. originally Arlec jam the battery between 2 bits of metal and its held in place by a sticker. Once you lift the sticker its fiddly, next to almost impossible to get it to sit back in a sturdy manner. When I replaced the battery I added the clip. But will rip this out again & replace with a rechargable AA for convenience. Can you think of any issues I may have with this? That battery & 1 X AA are both 1.2volts. Only issue I forcast is posible issues charging the AA internally from the timer... but thats for you lot to answer as I am unsure on that! This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Lapsy, I think I see what you mean but there appears to be a misconception of the timer function in your thinking. A timer is just an electronically operated switch. The switch part (a relay actually) can switch any voltage and it does not have to be the same as the one the timer requires to run. All you need to do is isolate the contacts of the relay from the rest of the circuit and use the contacts to switch 12V if that is what you want to do. Since the contacts in the original timer configuration are meant to switch 240V AC, removing the 240V parts already isolates the circuit. BTW, my timer does not look like yours at all but I do recognize some key components. The relay is that rectangular white box to the left of the thick red wire. Have a close look at the housing to see if you can find the relay coil voltage. If it says 24V/ 10A then its like my timer and you can run it on 24V. You need to remove that big white capacitor(under the white wire) and the small resistor that's connected in parallel to the cap. Also remove the big resistor to the right of the cap. There should be 4 diodes (it may be a bridge rectifier - black box under battery holder with 4 legs)that also needs removing. That should be all. The battery does nothing unless you disconnect the timer from its 24V power source in which case the battery takes over until it runs out or the 24V are restored. So, to sum up, use the relay contacts to switch your 12V (black & red wire?). Connect 24V - if its a 24V relay - to run the timer from. The timer takes very little running power, just a few milliamps but there must be a reasonable source of that for the extra 'kick' to turn on the relay when the timing setting(s) demands. Where to connect the 24V? Try the + and - where the bridge rectifier was and solder appropriate wires in there. After all, you replaced what came out of the bridge rectifier with an external source. Take care, keep the magic smoke under control  Klaus |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Yep 24V on the relay! Nice! Ok that youtube video is saying 12v..... http://www.youtube.com/watch?v=Cuz4iOu9v6U&feature=related Wondering if a USA timer on 110v would have a 12v relay, as this bloke seems to be in USA or Canada and the vid is poster as 12v setup? He does a good job on his garden. I am talking a few acres to be setup with food! Just experimenting for the best expandable setup and it came down to alot of factors. E.G Try getting 100 decent plant pots is not cheap! Thats why we think PVC pipe is the way. Don't forget you have to fill those plant pots as well. If they are 10 litres each & you have 100, thats alot of soil or other medium. Too expensive! PVC Pipe comes in 6mtre lengths, more compact, cheaper to fill, easier for plumbing.... Also Not everyone smokes mate... but I know everyone eats! Some even eat the smoke too....Yes your right it could be used for majic smoke for sure! Fish poo in the water, so there is your nutrients instead of folking out for super dooper claim to be number one and all this plant food. I will use goldfish to start with. I have sourced a place that sells Jade Perch & Barramundi, if we want to get the fish breading so we can start eating fish & chips! Actually thinking of starting a small nursery or supplying markets. I figure what you dont sell you just keep yourself, keep it growing and eventually eat it yourself. Refer to Murry Hallems Aquaponics in google for the full story and workings of these types of systems. I'm just morphing ideas from about 15 different websites at the moment for mine until something simple to operate comes out of it all. Will have a go at the above instructions on the weekend (hopefully). Appreciate the assistance so far! Very helpful! If I do not respond by Monday-Tuesday I've probably electricuted myself! Hahah.... This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Just thought...... I dont have a 24v power supply... Although, I could double up the 12v lines on an old computer power supply, as an IDE hard drive has 12 & 5v lines running into it. Thats all I have at hand I guess, or 2 car batteries I suppose... Could go and buy a fresh 24v batt also if I have a look around. Would need one that would be suitable for solar and thinking Sealed Lead Acid Hobby style from a batt place or Jaycar or ebay or something. Any suggestions on small batterys/brands that seem to handle the charging any better on a solar setup like this? Also thought of maybe using Radio controlled car batteries? Not wanting to have to buy a huge solar panel if I can help it either, but wondering if a 5-10W solar panel is good enough for the job? Note - I am in Australia. HaHa! Also.... you might like this idea... thought also, for a cheap pump, stripping the windscreen washer water pump out of car wrecks. Might not pump a decent volume of water though. Any thoughts or anyone tried this? This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Lapsy, you are thinking way too complicated to get 24V. Have you got a spare $A2.50? If so, check this out: dc to dc up converter I'm using these for all sorts of things, great cheap gadgets and should run your digital timer off a 12V battery no worries. Re windscreen washer pump, I think these are only intermittent rated, might not go for long. Note, I too am in Australia Klaus |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Ok! Fair call. I will go for that. Definatly a cheaper way round for me... I shall return soon! Cheers to all so far for the trouble shooting! This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Ok, found the step ups on ebay for about $17 buy it now. The one youve shown is in auction so I will check the auctions... Also - Other stuff around $17 I have looked at for an alternative in the past... http://www.kitstop.com.au/page15.htm - irrigation and sprinkler controller (inc water sensors and autofeed) http://www.jaycar.com.au/productView.asp?ID=KA1732&keywords= timer&form=KEYWORD Comments? Anyone using these? The kitstop one looks interesting but it is not operated on a timer. Soil sensors regulate feeding. Unsure if this would give you enough room to tweek the setup in regards to plant response, as it's all on what the sensors feeling, so positioning may have to be perfected. Might not react well in summer either. Anyone using this type of method to irrigate? Did also find this cheap which is what you suggested Tinker for a $7 buck bargain... http://www.ebay.com.au/itm/DC-DC-Boost-Converter-Step-Up-3-5 -30V-4-30V-Module-Powr-Supply-/130626656833?pt=LH_DefaultDom ain_0&hash=item1e69f49a41 This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Lapsy, you managed to figure out how to post pictures so its time you get the hang of posting hyperlinks . Most of us can't be bothered to copy and paste long URL's  .
Again, look at the header in the reply box. The fourth icon from the left (looks like a globe wearing goggles) under the word "font". Click that and follow the instructions. Simple  Klaus |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Here is the Hyperlinked summary of this thread... Silicon chips timer My Timer jaycar Flexitimer Kit $20 Kitstop Soil Sensor Sprinkler & IrrigationKit for about $18 Delivered... Then there is the Step ups on ebay from who/wherever you can get them cheap. Your auction ended so.... no hyperlink to a dead listing. The bloke on youtube with a wall timer modded for 12v Murry Hallems Aquaponics Setups - How the Pro's do it properly... Done! 
This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Well done Lapsy, I knew you'd work it out .
Hydrophonics is not my thing though, I just grow my veggies the conventional way in raised beds with drip irrigation. For that I purchased a commercial timer that plumbs into the water pipe. Klaus |
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