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Topic: Keyboard Instrument Project 07: Extra resistor (Read 1 time) previous topic - next topic

Zhulander

What is the extra resistor that connects the buttons to ground for? I see a lot of "extra" resistors like this in the other projects that I would not have otherwise thought to put into the circuit. Does it have something to do with the voltage going back to the ground?

dannable

Most of the people who help on the forum don't have the kit, so a picture would help to illustrate the part of the circuit you are referring to.
Beginners guide to using the Seeedstudio SIM900 GPRS/GSM Shield

Zhulander

#2
Aug 30, 2015, 10:56 pm Last Edit: Aug 30, 2015, 10:58 pm by Zhulander
O my bad, attached is an image of the circuit. it's the 10 kohm resistor that goes back to the ground that I'm confused about.

dannable

If it wasn't for the 10K resistor, when all the switches were open then A0 would be 'floating', and if you read it you would get pretty random values. The 10K resistor clamps it to ground so with all switches open it will read zero.
Beginners guide to using the Seeedstudio SIM900 GPRS/GSM Shield

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