Voltage regulators for electrical horology

I am making two different regulators for antique battery clocks.

Model 1 - Low current, high efficiency
The first style is designed to drive low power battery clocks like Bulle, Eureka, Brillie and ATO that run on 1-1/2 to 3 volts. Normally these clocks use either one or two battery cells. But the voltage changes as the batteries age, and the rate of the clock is likely to change as well.

There are several benefits to driving one of these clocks with a regulated supply:

  • The clock will be more accurate if the voltage is contant.
  • You can make fine adjustments to the voltage, which usually makes a fine adjustment to the clock rate. In other words, you may be able to fine tune the clock rate with the regulator.
  • You can drive the regulator with four "AA", "C", or "D" cells. This allows you to have more battery capacity than a single cell or two.
  • You can tailor the voltage to produce optimum motion of the pendulum or balance wheel.

This circuit can supply up to 250 milliamps of power and the standby current draw is only about 20 microamps. This means the batteries will last a long time and not be drained by the regulator. 250 milliamps is plenty for the clocks mentioned above. Clocks that use more power, however, may overload this regulator. For example, a Synchronome is likely to require more current. The second style of regulator, shown below, is more appropriate for higher current clocks.

The circuit has a 10-turn potentiometer for setting the voltage, allowing very fine adjustments. The output range is 1.25 volts to 6.5 volts. Higher limits are available on special request. It is small enough to fit easily inside the clock.

The cost is $35 plus $4 postage in the US. California residents must pay 7-1/2% sales tax.
To place an order, go to the Clock Circuits Order Entry Page.

Model 2 - Higher current with battery backup
The second design will support higher loads, providing up to one amp of regulated current. (Clock loads are usually intermittent. Sustained loads at full current may require additional heat sinks.) This design is suitable for clocks like Synchronome, Standard Electric, and the Self Winding Clock Company. The circuit is not as efficient as the previous style, and will tend to drain a battery over time. Therefore, it will usually be driven by an AC adaptor rather than batteries. An AC adaptor is provided that will deliver up to one amp from 110 volt lines (domestic United States).

Regulation is accomplished with a small 10-turn potentiometer that will allow you to set the output voltage from 2.5 to 7.5 volts. The circuit also features a jack for a 9 volt backup battery in case the AC fails. This will keep the output voltage at the proper level (and keep the clock running) for short outages of the AC line. For greater protection against power outages you may want to supply a larger battery for the backup. For example, a 12 volt gel cell could be used.

A 2.1 mm barrel jack is provided for input voltage from the AC adaptor. Solderless connectors are provided for the voltage output to your clock. A nine volt battery snap connector is provided for the backup source.

The cost is $55 plus $6 postage in the US. California residents must pay 7-1/2% sales tax.
To place an order, go to the Clock Circuits Order Entry Page.

  

To place an order, go to the Clock Circuits Order Entry Page

 

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