In SX Microcontrollers, SX/B Compiler and SX-Key Tool, mgreen wrote:

The 1N4004 connected with anode to IN and cathode to OUT will bypass the regulator and burn out your equipment.

1) I would suggest using one of the more modern regulators designed for automobile use like the LM2940.  It doesn't need the diode and is protected against reverse polarity input and input voltages to 26V (with transients to about twice that).  It does REQUIRE an output capacitor, preferably a 22uF (or higher) 6V Tantalum capacitor optionally with an electrolytic capacitor of higher value in parallel with it.  You should have a 0.47uF input capacitor with a rating of about 30-50V

2) Cars are very electrically noisy environments.  The regulator will help keep the supply voltage constant, but noise will get through.  You can add a choke on the input as well as additional input capacitance (both small like 0.1uF and large values like 100uF with a 30-50V rating).  Keep in mind that noise can travel in on other wires like sensors and even on output wires like servo control signals.  Shielding helps.  Avoid ground loops.

---------- End of Message ----------


You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=197897#m197902

Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com

The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2007 (http://www.dotNetBB.com)