Pin out resistor

-

hi,
i have little 4wd robot car driven 4 of pwm pins on uno. each output pin goes through resistor base of npn transistor drives motors. each motor draws 250ma.

it works well, don't understand need resistor between pin , transistor base. experimentally seems make no difference if there or not. when there current drawn each pin 290ua , when isn't there current 300ua. i've read important component, can't see purpose if i'm doing saving 10ua. can clarify?

thx

the base-emitter junction acts diode ground.  if don't put in resistor , set output high shorting 5v ground.  draw current pin , overheat arduino.


Arduino Forum > Using Arduino > Motors, Mechanics, and Power (Moderator: fabioc84) > Pin out resistor


arduino

Comments

Post a Comment

Popular posts from this blog

opencv3, tbb and rasp pi 2 - Raspberry Pi Forums

-
Image
has installed opencv 3.0.0 tbb enabled on latest rasperian on pi 2? followed guide here viewtopic.php?f=28&t=110025&p=761255&hi ... v3#p761255 differences made enable tbb via cmake... added build , tbb options shown.. cmake -d cmake_build_type=release -d build_tbb=on -d with_tbb=on -d cmake_install_prefix=$(python3 -c "import sys; print(sys.prefix)") -d python_executable=$(which python3) .. patched current, dependencies installed far can tell.. cmake reports going install , old version of tbb... -- use tbb: yes (ver 4.1 interface 6102) make process fails linking problem don't understand fully, [ 66%] built target opencv_features2d scanning dependencies of target opencv_test_flann ../../lib/libopencv_imgproc.so.3.0.0: undefined reference `tbb::task_group_context::cancel_group_execution()' ../../lib/libopencv_imgproc.so.3.0.0: undefined reference `tbb::interface5::internal::task_base::destroy(tbb::task&)
Read more

small ethernet problem - Raspberry Pi Forums

-
hello, after conventional installation raspbian noobs v 1.4 raspberry pi 2 . how can configure internet connection on raspberry me download apt. (my ethernet cable connected directly ethernet switch (i'm @ university)) attached configuration of pc internet connection. http://i.imgur.com/budyoeb.jpg thank much, google configuring rpi static ip address. use same ip numbers see on pc. not try have both pc , rpi connected network @ same time. raspberrypi
Read more

Multithumb configuration params not working? - Joomla! Forum - community, help and support

-
hi, i've installed multithumb 1.1 on joomla 1.011 site , works fine in basic set-up (and jce-editor). except when try tweaking mambot params, things stop working. specifically: if use "only in these categories" setting , fill in categoryname, e.g. "news", pop-ups/thumbnails stop working, categories, including "news". if use "not in these categories" these categories still use pop-ups. if select "use thumbnails" "no" not no thumbnails no pop-ups anymore. so way use multithumb selectively use optioni "apply content {multithumb}", bit cumbersome. there more people having these issues? hi bikey, i having issues bit different - yet same.  saying have way set configuration plug-in.  not know how find cong this.  if can maybe read posting - don't bore process.  jce editor - have not installed - still using default html editor - cant recall name.  why not see config file? anyway - find if use static page , pass com
Read more