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I think I burnt my Dongle! — Parallax Forums

I think I burnt my Dongle!

PerryPerry Posts: 253
edited 2011-03-13 08:29 in Propeller 1
Well at least one pin on it anyway.

In trying to make an infrared repeater and infrared keyboard it appears I have blow out pin one.

Things looked good at first until I moved my test into the TV room and then nothing but @#!&#.

Does any one have recommendations on the minimum value resistor that can be used on the prop to drive a infrared LED.

would such a burnout affect nearby pins?

Hubristic Perry

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-03-12 14:17
    Why all the resistance to transistors?
    What's the fear?

    PE -- Assuming 1.5V (V_led) and 40mA, pushing the envelope...
    drum roll, please...
    47Ω
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2011-03-12 15:57
    Almost any small signal transistor will do. Here in Australia, the BC547 is a very common type. I think in the US the 2N2222 is popular.

    Put a 1k to the base to limit the drive current into the transistor, then use the 47 ohm resistor in series with the led as per PJ Allen. Two resistors, one transistor, total cost = about 10c.
  • ctwardellctwardell Posts: 1,716
    edited 2011-03-12 16:45
    The title made me laugh, I needed that, working far too long on the weekend.
  • PerryPerry Posts: 253
    edited 2011-03-12 21:32
    Good news, my Dongle is OK after all.

    I can't figure why it was not working yesterday, spent a lot of time checking the hardware.
    I did have a diode in series with the infrared LED, hoping to keep things from burning.

    I found a MPSA43 in my junk box and used that and the suggestions from PJ Allen and Dr_Acula to finish the project.

    I had also wanted to put a little levity to the forum

    Here is the code I have been trying out. (it's mostly code from Bob Belleville IR_KIT found in the OBEX

    It's a combo IR_Keyboard and IR_Repeater

    should be useful to automate IR functions of multiple remotes.
    zip
    zip
    IR_KB.zip
    41K
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2011-03-12 22:17
    Perry wrote: »
    I think I burnt my Dongle!

    Ouch!
    That has never happened to me, I guess I am just careful. :-)

    I did sit on a hot curling iron once though.......
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2011-03-12 23:44
    Holly, I'm sure you will appreciate the Dongle joke that comes up about half way through this sketch http://www.youtube.com/watch?v=kAG39jKi0lI
  • AriAri Posts: 63
    edited 2011-03-13 01:19
    I love the smell of burning dongle in the morning.....wait....that sounds all wrong.....
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2011-03-13 01:39
    Dr_Acula THAT video . it made me laugh SO hard . there is so much epic win in it .......
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2011-03-13 03:45
    Most IR diodes are driven very hard for a low duty cycle. Up to 1A pulses for a few % of the time not being uncommon.

    ADDIT

    That sketch was a tribute to Ronnie Barker's "Four candles", He could twist every word, when he retired from TV he opened an antique shop not far from my parents house.
  • w4fejw4fej Posts: 264
    edited 2011-03-13 05:59
    " I think I burnt my Dongle "

    I hate it when that happens... Yikes, that's gonna leave a mark!

    Mike B.
  • doggiedocdoggiedoc Posts: 2,245
    edited 2011-03-13 06:25
    Dr_Acula wrote: »
    Holly, I'm sure you will appreciate the Dongle joke that comes up about half way through this sketch http://www.youtube.com/watch?v=kAG39jKi0lI

    Good One Dr_Acula! That's full of laughs!

    @Perry - sorry to hear about your Dongle problems. As PJ noted - a small resistor is good insurance for the other 31 pins.

    Paul
  • BigFootBigFoot Posts: 259
    edited 2011-03-13 08:29
    Dr_A, great video, very funny.

    Perry, it is never a good idea to have a processor drive large currents to a load. Processors
    are designed to process, transistors are designed to drive large loads. 2N3904's and 2N2222's
    are very inexpensive and will drive your Ir Led fine.
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