Posts with «limiting» label

New Project: Limit TV Time with an Arduino-Controlled Relay

Most of us spend far too much time in front of the TV. So I designed a system that will automatically limit when and how much the TV can be on.

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The post Limit TV Time with an Arduino-Controlled Relay appeared first on Make: DIY Projects, How-Tos, Electronics, Crafts and Ideas for Makers.

MAKE » Arduino 16 Sep 19:00
arduino  automatic  diy hacks and how tos  diy_hacks  diyhacksandhowtos  electronics  exercise  jason poel smith  limiting  tv  tv limiter  

QRD1114 Resistor Values

Hi all,

I'm using a QRD1114 sensor for a line-follower. Datasheet: http://www.fairchildsemi.com/ds/QR/QRD1114.pdf

Im hooking it up with this schematic:

However, I'm unsure how the value for the 10K resistor was calculated? It's acting as a potential divider, right?

For the LED im guessing that the value of 220 was taken from doing:

R=(Input Voltage - Max Forward Voltage)/(Optimum forward current)

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Let's Make Robots 01 Jul 21:05
absolute beginners  arduino  current  divider  follower  following  limiting  line  potential  qrd1114  resistor  voltage