Shop OBEX P1 Docs P2 Docs Learn Events
Fried BS@ — Parallax Forums

Fried BS@

bluejaybluejay Posts: 131
edited 2012-11-16 10:14 in BASIC Stamp
I accidentally fried my BS2 when attempting to control AC X-mas lights with a relay. I purchased another BS2. Could someone advise me a device that would prevent this from happening again?
Perhaps an optoisolator of some kind. I am using a ULN2803 driver and am contemplating using a TPIC6595 which is high current 8-bit shift register.Thanks in advance.

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2012-11-09 04:53
    The ULN2803 should have been enough, depending on what you did.
    If you didn't connect the ULN's "COM" (pin 10) to the relay's +V then you would only wipe out that gate.

    So, out with it. What was the accident?
    If you touched AC to the wrong pin or something, there's nothing practical that could mitigate that sort of thing.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-11-09 07:26
    bluejay wrote: »
    I accidentally fried my BS2 when attempting to control AC X-mas lights with a relay. I purchased another BS2. Could someone advise me a device that would prevent this from happening again?
    Perhaps an optoisolator of some kind. I am using a ULN2803 driver and am contemplating using a TPIC6595 which is high current 8-bit shift register.Thanks in advance.

    The relay was actually suppose to provide excellent isolation. Having yet another layer of isolation is not necessary, but the ULN2803 tends to be a 'sacrificial IC' if something really goes wrong.

    It would seem to all be a basic wiring problem. Damage to the BS would have to take on one of two forms. Either you provided reverse polarity to the BS and that was fatal to the entire device, or you did something that may have damaged i/o pins (usually limited to one pin). I suppose you could have done something else (like providing 5 AC directly to the +5 volt pin), but it is hard to imagine that you might be that confused.

    What we need to know in order to help is the exact nature of the damage to the BS. Completely destroyed or damaged i/o.

    The ULN2803 is an excellent device when you use it properly as it provides 60ma to each relay and has diode protection for the Darlingtons. But some would argue that another flyback diode should be used across the relay coils to reduce noise in the circuits.

    It would also help to know the following:

    1. What is your power source for the Basic Stamp?
    2. What are the DC voltage rating for the relays? If you used AC relays with AC power, that is your problem point.
    3. Where are you getting power for the DC relay coils and the ULN2803?

    Personally, I use socketed relays when working with 120VAC mains and the sockets are marked clearly where each wire should go. The sockets are then held on an aluminum DIN rail so nothing is unclear or messy.
  • ercoerco Posts: 20,257
    edited 2012-11-09 09:18
    Or stick with premade relay modules, they're cheap: http://www.ebay.com/itm/4-Channels-5V-Relay-Module-for-Arduino-ARM-PIC-AVR-DSP-aii-/261039876391?pt=LH_DefaultDomain_0&hash=item3cc7306927
  • ercoerco Posts: 20,257
    edited 2012-11-09 13:15
    BTW, I'm from the south, where everything's better fried.

    X'cept BS2s.
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-11-14 07:48
    BTW, I'm from the south, where everything's better fried.
    Probably right. Way back in 2000 I barbecued a BS2. True story. It was a custom made wood pellet barbecue.
    Lost my shirt and a BS2 on that one.
    -MattG
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-11-16 10:14
    Try adding soy sauce and wasabi, maybe a bit of ginger, red pepper and garlic in the soy sauce. Of course one must chew very carefully as to not damage fillings.

    OP has been ignoring this thread..... I hope that he is alright. 120VAC or 240VAC are not beginner projects. The wiring has to be 100% right.
Sign In or Register to comment.