Step 4: Assembly


Assembly is pretty basic if you refer to the schematic drawing.  If I had paid closer attention to the size of the battery holder vs the inside of my box, I would not have had to do some work with my dremel tool to grind down some inside corners of my box to have things fit properly.

I used a piece of double sided tape to attach the small relay to the side of the battery holder.  These two parts then fit snugly into the case.  I then soldered the rest of the wires to the exposed connections on the relay.  Your relay should come with a diagram showing which pins are for which purpose.

I then made a small notch in the side of the case for the input / output power cables to exit.  A small cable tie on the inside of the box provides strain relief for the cables.

<p>This is something that drives me crazy. A simple idea/product that would be useful and even obviously necessary, yet it does not exist.<br><br>In the early 90's I had a Sanyo cordless phone with batteries in the base station for just this purpose. It worked like a charm- I could use it even when the power went out. Now... cordless phones have no backups and are little better than bricks when the wall power goes out. The same can be said for things like WiFi routers. Your internet is still active but the power is out. Why not have a few batteries in the thing to keep it going for a little while?<br><br>Or why not have adaptable/adjustable backup battery packs for small items like phones, clocks, radios, and wireless routers? Exactly like this Instructable.<br><br>This is a product I would gladly buy. Turns out it doesn't exist. Your Instructable is the closest thing to a solution I have yet found. One more reason to learn basic electronics and the use of a soldering iron.<br><br>Thank you.</p>
&nbsp;Thank you for a good and useful Instructable. &nbsp;I had wanted to do something like this on an older digital alarm clock. &nbsp;But, I was pretty certain the time lag for the relay to engage would still cause the display to lose its setting. &nbsp;I have wondered if a capacitor across the leads would supply enough power until the relay engaged. &nbsp;I have also thought about wiring batteries across the power leads. &nbsp;The AC supply would keep them charged. &nbsp;If the AC went out, the batteries are immediately on-line. &nbsp;But, we no longer have that clock.
I would like to see a diagram and possibly a model of that very set up you just described. I'm looking to power our battery opperated keyed deadbolts with AC and turning the batteries into the backup.
<p>Thank you for your comments.</p> <p>If you look at the circuit drawing, putting a capacitor across the cable to the base unit would not help since when the relay is energized (that is, AC power available), the capacitor is ALSO across the relay coil, and the input voltage, so when the input voltage goes away, the capacitor would not only be supplying power to the base unit, but also be holding the relay on for a short time... then when the capacitor drains, the relay clicks off, and you still end up with a short lag time as the contact switches to the battery pack.&nbsp; This is the problem with this simple &quot;external&quot; solution.&nbsp; You'd have to do some hacking inside the base unit, or...</p> <p>Change the whole design... keeping a rechargable battery across the input power, (as you mentioned),... along with the proper electronics to regulate the trickle charge to the batteries.&nbsp; This is what is usually done in commercially produced products that incorporate automatice battery backup.&nbsp; But once again, the key here was simple and inexpensive.<br /> &nbsp;</p>
I have had this Idea for about 15 years and decided to Invent it,,so,,i thought to do a search to see if it was out there ,,and low and behold,,here it is being discussed,,well,,Dont know what to do with this idea now,,seems everytime i think i have an invention or idea,,its out there,,i actually was the man who come up with the Voice Activated trolling motor,,long story short,,2 yrs passed,,so i lost all rights,,did not have the money to start it and the Company i submitted the idea to took it and patented the idea and today,,it is a big deal with serious pro fishermen,,What do i Do ???,,i have so many idea's like this,,i dont sleep at night and that is when all these invention's or idea's come to me,,,Can anyone help ??? everytime i find a place ,,they want an outrageous price for the Patent,,and i honestly dont have the money to back me up...Thanks for any help you may have...........
nice and simple ideia, how could i miss that =P<br>but in my case, the circuit must recharge the batteries automatically when not in use (Li-ION) hmmmm..<br>but for now i will stick to your ideia, thanks alot for sharing this m8 =D
I like this, gives me some ideas for other things. I normally have my phone hooked to my computers battery backup but this is just cool. It would be even cooler if they were rechargable batteries that charged by the wall outlet.
<p>This is a great idea, during IKE&nbsp;last year we had to use a corded phone to get be able to use our home phone (as the cell phones are&nbsp;crap in emergencies),&nbsp;I&nbsp;just had a battery back up die......so I&nbsp;wonder if I&nbsp;can implement come of the remaining parts from that......hmm this just might work.....<br /> Great Instructable Very informative</p>

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