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BS Homework Board USB - Power Supply Voltage Range? — Parallax Forums

BS Homework Board USB - Power Supply Voltage Range?

T-townT-town Posts: 17
edited 2014-04-21 09:53 in BASIC Stamp
Hi. What is the voltage range that I can use to replace the 9 volt battery with a power supply? The reason I ask is that I have 12 volt dc outputs (via a relay), and it would be handy if I could use the same source to eliminate the battery that feeds the board. Thanks for your help. Joe

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2014-04-20 12:26
    The only thing normally connected to Vin is the LM2940 regulator which is rated for in excess of 26V. Usually the limiting factor is the heat dissipation which is determined by Vin-5V x current output. The Stamp itself and the circuitry on the Homework Board doesn't take much current, so it mostly depends on what you've connected to the 5V regulated supply (Vcc or Vdd). If you're not using a large servo that runs all the time, you can probably do just fine with a 12V supply. Make sure the 12V supply is well filtered and doesn't have a lot of noise on it from a motor or several relays.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2014-04-21 09:53
    Agreed. Typically 12V is fine on the input of the HomeWork Board unless you have an older revision before the regulator was upgraded to the TO-263 package that is currently used. It has been in use for quite some time, however prior to that there was a smaller regulator on the Serial version.
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