Award clock put to good use as a bench meter

award-clock-turned-voltage-meter

The motivation industry turns out these type of award trinkets by the millions. Here’s a way to actually put the thing to use. Instead of displaying time, the clock dial serves as the readout of a voltage meter.

When we first saw this post we assumed that the hack used some type of coil injection to drive the hands. But it turns out that this is mechanically driven. The image above shows the stepper motor which is mounted behind the clock. Its drive shaft is coupled with the adjustment knob on the back of the clock. The precision of the motor lets the PICAXE set the clock dial based on the number of motor steps. The hour hand shows the tens value with the minutes serving as ones (base 10, not base 60). This means the top measurable voltage is 12V — when the hour hand is at 12 the measurement is 0 volts plus tenths of a volt from the minute hand. With the dial taken care of the rest of the project focuses on measuring the voltage using the ADC, which has an upper limit of just 5V. This is overcome with a simple voltage divider.

After the break you can see the accuracy of the rig as it performs measurements next to a digital voltmeter.

[Thanks Pat]

Comments

  1. Cold_Turkey says:

    Nice. Seems that it finds the voltage a little faster than the voltmeter, maybe due to a small load? Would be nice to see a vid showing more than 1volt tho

  2. BotherSaidMayans says:

    Someone totally needs to make a “Weasley Clock” out of this…

  3. emc2 says:

    I would think that this idea could be applied to the construction of homemade instruments for a panel in a flight simulator. The clock, with appropriate packaging, white hands, and a black scale would make a nice altimeter, for example.

  4. Peter says:

    the “Motivation Industry”, heh!

    Here’s what despair.com has to say about it:

    “If a pretty poster and a cute saying are all it takes to motivate you, you probably have a very easy job. The kind robots will be doing soon.”

  5. Drone says:

    The clock is already stepper motor driven internally. Why not just pulse the clock’s internal drive coil? It seems crazy to go through all the work of kludging up an external stepper for this application.

    I’m surprised he didn’t use an Arduino for this mess. But then again a PICAXE isn’t far removed from the Arduino crowd…

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