Time responsive variable voltage power supply

A variable voltage power supply comprising:

• (a) an input adapted to be connected to an alternating voltage source;
• (b) an output;
• (c) latching switch means having a terminal connected to said input, another terminal connected to said output, and a control terminal adapted to have applied to it a switching signal for latching said switch means into a closed condition to permit current flow between said input and said output during a sub-cycle of said alternating voltage, said switch means switching to an open condition to prevent further current flow therethrough in response to completion of said sub-cycle of said alternating voltage;
• and
• (d) control means for latching said switch means into a closed condition during each said sub-cycle of said alternating voltage, said control means including:
• (1) a user-activated voltage level setting signal generator having a control surface input adapted to be touched for a period of time and an output at which a voltage level setting signal appears in response to and during the period of time said control surface is touched;
• (2) an n-stage up-down counter having an incrementing input and a decrementing input responsive to a first source of periodic electrical signals, said up-down counter including means for storing a count representative of the last selected output voltage level during the last on output state of said power supply;
• (3) an n-stage cyclical counter responsive to a second source of periodic electrical signals, said cyclical counter having a reset input responsive to the output of a zero crossing detector, the input to said zero crossing detector being responsive to said alternating voltage;
• (4) an n-stage comparator for comparing the counts in said up-down and cyclical counters, respectively, said comparator providing when the stored count in said up-down counter equals the count in said cyclical counter said switching signal to said control terminal causing said switch means to latch into a closed condition and permitting current flow between said input and said output;
• and
• (5) timing means responsive to said voltage level setting signal for:
• a. inhibiting a change in output state of said power supply when the duration of said voltage level setting signal is less than a first predetermined period of time;
• b. effecting a change in output state of said power supply when the duration of said voltage level setting signal is greater than said first predetermined period of time and less than a second predetermined period of time;
• and
• c. effecting a change in output voltage level of said power supply when the duration of said voltage setting signal is greater than said second predetermined period of time and the output state of said power supply is on by selectively enabling one of said incrementing and decrementing inputs to said up-down counter, whereby enabling of said incrementing input causes said switch means to latch into a closed condition later in said sub-cycle of alternating voltage and enabling of said decrementing input causes said switch means to latch into a closed condition earlier in said sub-cycle of alternating voltage.