Scheme improves on low-cost keyboard


Posted on Jan 14, 2013

You can easily improve on a previous Design Idea to produce a slightly simpler resistor arrangement with better timing balance between switches, using a single resistor value (Reference 1, Figure 1). The use of a single resistor value, RS, in a series chain for the switch resistors gives the timing parameters a simpler format and should reduce bill-of-materials cost. The timing balance between switches should now also be more even.



The improved balance eases extending the keyboard for adding key inputs. The additional benefit of this arrangement is to make the circuit easier to adapt for faster or slower microprocessors, because you can easily adapt the circuit by changing the singl




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