Quartz Clock Power Supply Hack (AA Battery to AC Power)

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I had a quartz wall clock in my workshop that ran a AA battery power.  The battery died so I decided that rather than buy a battery, it would be more fun to convert the clock from battery power to AC power.

Step 1: Tools


For this project, the only tools that you'll need are a soldering iron and (optionally) a hot glue gun.

Step 2: Parts


You will need:

(1) 5V power supply .. I used an old phone-charger .. these can be readily found at any thrift store
(2) 22uF caps rated for 10V or better
(3) silicon diodes .. I used 1N4936 because it's what I had lying around .. but most any silicon diode will do .. the forward voltage drop will vary slightly for different diode types, but this circuit is fairly tolerant of small voltage differences.
(1) 1K resistor .. the power rating doesn't matter much, the resistor will only need to handle milliwatts of power

Step 3: Schematic


Here is the schematic ..

Step 4: Point-to-Point Wire the Circuit


Just connect up the circuit as per the schematic.  Keep the leads relatively short so the entire circuit will fit in the space that was previously occupied by the AA battery.  Once wired, you should check the output voltage with a multimeter.  It should be somewhere between 1.5V and 1.6V

Step 5: Hot-Glue the Circuit in Place


This is somewhat optional, but it's nice to encapsulate the circuit ..

Step 6: We're Done ..


Sit back and admire your work :)

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    29 Discussions

    0
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    Petethepens

    Question 19 days ago

    Hi all I
    have built circuit and works fin on quartz clock but won’t work on radio controlled
    clock.


    I presume it
    upsets the receiver of the clock unit as it has a very long frequency ferrite coil
    aerial.


    Any ideas?

    4 answers
    0
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    scdPetethepens

    Reply 18 days ago

    What voltage does the radio controlled clock run on?
    If the radio controlled clock uses 1.5V, then you could try a linear 1.5V regulator.
    Search eBay or Amazon for "DC to DC 1.5V buck converter".

    0
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    Petethepensscd

    Reply 18 days ago

    Hi SCD thanks for getting back to me, yes clock
    is 1.5v and circuit is giving 1.43v so no problem there I think perhaps the DC
    is not clean enough for the electronic board in the unit. Do you think more smoothing
    would do the trick? And if so how do I go about it?

    0
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    Petethepensscd

    Reply 16 days ago

    I think I
    have solved the problem by putting a NiCad battery in parallel thereby smoothing
    everything out. I know the battery is only 1.2v but clock mechanism seems to be
    quite happy with that. It is pulling the whole circuit down to 1.2 but nothing
    is getting warm and only pulling 3mA. Having looked on the net for instructions
    for charging NiCad battery’s it seems that sitting with a small current will keep
    the battery charged and can be left in circuit. By the way the clock only uses
    3mA every 30 seconds when there is a brief pulse and the hands move otherwise
    it uses .08mA.


    Did think
    of getting a regulator but that takes the fun out of the project as all the
    bits have come out of junk items so far.

    0
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    mgnscott

    Question 2 months ago

    Fantastic! This is exactly what I am trying to do! But I sure wish a kind soul would explain the schematic to me, I know roughly what the schematic is and could make it on a breadboard but I don't really know WHY I would be using each of these components. I really like to understand on a basic level what each part is doing before making. If anybody feels like dedicating some time to someone who needs to know things in too much detail please reply. (ps yes googling individual parts gives an idea but not really, example, why 2 caps, why 3 diodes etc...I have a very basic understanding of electronics so feel free to talk to me like a child)

    2 answers
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    scdmgnscott

    Reply 2 months ago

    The circuit was a hack way to generate a 1.5V power for the clock with parts that I happened to have on hand. The 3-forward-biased diodes creates an approximate 1.5V reference, and the caps store enough charge to supply current for when the clock ticks. A better way to generate 1.5V would be a buck converter. If you search on Google, or eBay or Amazon for "1.5V Buck converter" you can find a part that will do the job for less than $1.

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    mgnscottscd

    Reply 2 months ago

    Tried your way and with a converter and still no joy. Thanks anyway.

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    james lawler

    Question 8 months ago on Step 2

    I have a multi voltage power supply starting at 1.5 volts. My quartz clock has two 1.5 batteries; can I hook the power adapter directly to the two batteries without any diodes or other parts?

    1 answer
    1
    None
    scdjames lawler

    Reply 8 months ago

    Are the 2 batteries in series? If so then you'll need a 3V supply.

    1
    None
    robrhy

    2 years ago

    Can't follow schematics.Anyone have a drawing of how to wire this up please.

    1
    None
    HuaY1

    2 years ago

    can i know which is + and - cable power?

    1 reply
    0
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    scdHuaY1

    Reply 2 years ago

    You will need a voltmeter.

    0
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    plojm

    2 years ago

    I had 1 47uf 25v cap and tried to use that instead of 2 22uf ones, it seems to work for a little then not work. What is the formulat i get almost 1.6vs out exactly but ma s of power i dont know. u can hear the clock tick sometime then slow down for some reason

    0
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    MaxwellF4

    3 years ago

    I've come across this tutorial thinking of ideas for a lamp I want to build.

    If someone is still reading these comments, I had a few questions regarding the wiring.

    First, my idea is to build a desktop pipe lamp (like a steampunk style) with one or two bulbs, but also add a small clock to the mix. I like the design of some of the lamps with old gauges, and figured I could replicate the look, but have a clock instead that's fully functional compared to a gauge that's decorative. I would like the whole fixture to run off AC power though, and every small clock (4" or less in diameter) I would find would run off batteries of some sort (many which are AA that I have been looking at.)

    For this setup, could I incorporate the circuit for this setup into wiring for a lamp? I'm a little confused with the diagram on what goes where also. According to the diagram, there is a ground wire that comes out, a wire that has 5v, and a wire that has 1.5v. Which of these wires is attached to where the battery would be, and is there only one wire that goes back to the wall plugin then?

    To me, it looks as if the ground wire is the only wire that goes into the wall outlet (but I'd think the 5V one comes from the outlet, as you can see I'm confused here.) If the ground wire is the only wire heading to the wall outlet, could that be incorporated into the ground wiring for the bulb/bulbs for the lamp?

    Worst case scenario for me, I'd just incorporate two different plugs for my fixture. That way I could setup the lamp portion to be on a remote outlet and the clock to be continuously on. Having one plug for the entire setup would be nice though.

    Anyways thanks for any help and nice tutorial too. At the very least the tutorial will give me some more ideas on what I want to do.

    3 replies
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    scdMaxwellF4

    Reply 3 years ago

    Hi Maxwell,

    There are 2 wires (+5V and GND) that you need to connect from the 5V phone charger to the schematic in Step 3.

    Regards,

    ---------- original message ----------
    From: MaxwellF4
    Date: Dec 27, 2015. 9:19 PM

    Oh okay. It appears that the 5V phone charger only has one wire coming from it. If that is so, do I just take that one wire (after cutting off the phone charger portion and unsheathing it) and splice it anywhere along the diagram in step 3, such as after the diodes?If so then that sounds very simple. Thank you for taking the time to respond also!

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    scdMaxwellF4

    Reply 3 years ago

    Hi Maxwell,

    Nothing in the schematic of Step 3 connects directly to AC power. If you look in Step 2, you will see a 5V DC power supply (a re-purposed phone charger). The 5V DC output of this power supply connects to the circuit of the schematic of Step 3. If this is still confusing to you, then please let me know.

    Regards,

    0
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    MaxwellF4scd

    Reply 3 years ago

    Oh okay. It appears that the 5V phone charger only has one wire coming from it. If that is so, do I just take that one wire (after cutting off the phone charger portion and unsheathing it) and splice it anywhere along the diagram in step 3, such as after the diodes?

    If so then that sounds very simple. Thank you for taking the time to respond also!

    0
    None
    nathanziarek1

    3 years ago

    (Hopefully someone is still reading these comments!)

    I have a project where I'm building something like clock wall they show in movies involving the President (you know, the ones that show DC time, London, Shanghai, etc).

    I have four clocks that I bought from a thrift store, so there's no information on them. Each take a single AA battery and are just the basic second / minute / hour hand configuration like the one shown in this instructable.

    I have a 6v adapter providing 500 mA. My questions:

    1. I have no idea what the draw is of these clocks, but I have to assume its low. Will 500mA be enough to run all four of these?

    2. If this will even work, I assume I'll be wiring these in series, not in parallel, correct?

    Appreciate your time!

    1 reply
    0
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    scdnathanziarek1

    Reply 3 years ago

    The current draw for each clock is very low and it is not constant; most of the current draw happens once per second when the second hand ticks and (if I recall correctly) it was less than 1 mA for the clock that I used.

    If you are going to build the power supply hack (as described in this instructable) for each clock, then you would run the 6V to each clock (in parallel).

    It may be simpler to build a single 1.5V power supply using a MCP1702T voltage regulator and then run the 1.5V to each clock (in parallel). As an experiment you could wire all 4 clocks (in parallel) and try running them from a single AA battery. If this works, then great. If it acts funky, then you may need to add a cap to each clock to help supply the instantaneous current draw when the second hand ticks. Some experimenting will be needed on you part, but that's all part of the fun :)

    Here is a digikey link for the MCP1702T 1.5V regulator:
    http://www.digikey.com/product-detail/en/MCP1702T-1502E%2FCB/MCP1702T-1502E%2FCBCT-ND/2179250

    And here is a link to the MCP1702T data sheet:
    http://ww1.microchip.com/downloads/en/DeviceDoc/22008E.pdf