Skip to main content
Electrical Engineering

Return to Answer

added 57 characters in body
Source Link
user131342
user131342
  • 1.2k
  • 1
  • 6
  • 7

An alternative approach is to use a LM3914 to drive the LEDs, with an external 10-resistor ladder powered from the reference voltage. Then the rotary switch simply selects a voltage from the ladder which will light the required number of LEDs.

This is just an outline; for example, the topmost resistor of the ladder would be selected to set the step voltages within the tolerance (which in my experience is pretty tight) of the LM3914 comparators.

In addition, the whole thing will run off 3.3V supply

An alternative approach is to use a LM3914 to drive the LEDs, with an external 10-resistor ladder powered from the reference voltage. Then the rotary switch simply selects a voltage from the ladder which will light the required number of LEDs.

This is just an outline; for example, the topmost resistor of the ladder would be selected to set the step voltages within the tolerance (which in my experience is pretty tight) of the LM3914 comparators.

An alternative approach is to use a LM3914 to drive the LEDs, with an external 10-resistor ladder powered from the reference voltage. Then the rotary switch simply selects a voltage from the ladder which will light the required number of LEDs.

This is just an outline; for example, the topmost resistor of the ladder would be selected to set the step voltages within the tolerance (which in my experience is pretty tight) of the LM3914 comparators.

In addition, the whole thing will run off 3.3V supply

Source Link
user131342
user131342
  • 1.2k
  • 1
  • 6
  • 7

An alternative approach is to use a LM3914 to drive the LEDs, with an external 10-resistor ladder powered from the reference voltage. Then the rotary switch simply selects a voltage from the ladder which will light the required number of LEDs.

This is just an outline; for example, the topmost resistor of the ladder would be selected to set the step voltages within the tolerance (which in my experience is pretty tight) of the LM3914 comparators.