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Too Much Current on BS2 Stamp? — Parallax Forums

Too Much Current on BS2 Stamp?

SS Posts: 8
edited 2008-12-17 18:52 in BASIC Stamp
Well, the idiot at RS Electronics sold me a 5V relay but didn't seem to care when I told him it had to be less then 20 mA for the coil current.· My question is, will trying to run this relay at 80 mA ruin just that specific pin on my BS2 stamp or the entire stamp?· Please, any information is appreciated!

Thank you,
S

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2008-12-15 03:07
    An 80mA load may damage the specific I/O pin used since there's a maximum load of 25mA for any single I/O pin. There's also an aggregate limit of 50mA for a group of 8 I/O pins (0-7 and 8-15) which this exceeds. The whole Stamp can handle a total of 100mA. Depending on the amount of time involved and good fortune, the I/O pin may still be ok. The only way to tell is to hook up an LED to the pin (with a suitable current limiting resistor) and see if the I/O pin still works. Remember to hook up the LED both ways (to ground and to +5V). There are sample circuits and LED blink programs in the "What's a Microcontroller?" tutorial.
  • SS Posts: 8
    edited 2008-12-15 03:11
    I checked the output with a voltmeter of several pins and found that some work and some don't. I will have to mess with it more tomorrow. I have a class project due this Thursday and am hoping the whole stamp isn't ruined or so am I. Hopefully Professor Wale doesn't read this thread... LOL

    Thank you Mr. Green for the information!

    S
  • dandreaedandreae Posts: 1,375
    edited 2008-12-17 18:52
    If you are unable to use your stamp please send me an e-mail at dandreae@parallax.com and I will see what I·can do to get you up and running.



    Regards,

    Dave




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    Dave Andreae

    Parallax Tech Support·
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