A digital potentiometer is an integrated circuit that has pins for the three standard pot lugs, power, ground, and serial communication. The approach used by the Taptation and advocated by many is the use of a microcontroller that controls a digital potentiometer. As current decreases, delay time increases. Note that as we increase the resistance, Ohm's law states that the current must be reduced because we have a constant voltage. This is achieved in most PT2399 delays with the use of a B50k potentiometer wired as a variable resistor and a small fixed resistor to prevent chip lockup. An internal +2.5V voltage is applied to pin 6, so the resistance placed from pin 6 to ground will determine how much current passes through it. The delay time for the PT2399 is set by the amount of current that is sinked through pin 6. If you want even more detail, I highly recommend studying the fantastic PT2399 analysis at Electrosmash. In order to understand the hows and whys of this, let's talk a little bit about how the delay time is set on the PT2399. Software Debouncing: Other solutions may include software debouncing, but the ones I have seen tend to use a debounce scheme that eats clock cycles and therefore limits how fast you can tap in. Hardware Debouncing: Most solutions don't implement hardware switch debouncing, which helps make for more accurate tapped in tempo Default firmware allows for the original tapped in tempo as a quarter note as well as dotted eighth and eighth notes.Įasily modified: The code is all in Arduino, so it's easy to customize it for what you want it to do Time Division Switch: Easily configured switch for dividing the tempo. Relative time adjustments: Adjust your time relative to the tapped in tempo. In addition to being DIY and inexpensive, the project presented here has some great features, as well, including: This issue can all be remedied with the use of one of the many ubiquitous microcontrollers out there. There are a couple of commercially available solutions, such as the Taptation found at, but where's the fun in that? This is DIY, after all. However, with all its advantages, it doesn't have an easy tap tempo function. ![]() It is a digital IC, but it is implemented much like any other analog component into various circuits. The PT2399 chip has been the go-to standard for DIY delays for years.
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