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Freeway Blaster 12V 130db Electric Horn — Parallax Forums

Freeway Blaster 12V 130db Electric Horn

Thomas FletcherThomas Fletcher Posts: 91
edited 2009-12-24 19:48 in General Discussion
I would like to wire up one or more of these electric horns with the propeller and a motion sensor. Already thinking
of next year's Halloween.

It is made to be connected to a car's 12v battery and I was wondering if
a darington array would provide the propeller with enough protection from the current of a 12v battery.

Comments

  • FranklinFranklin Posts: 4,747
    edited 2009-12-21 16:37
    Could you post a link to the horn in question? You can always use the darlington to power a relay to power the horn.

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    - Stephen
  • ercoerco Posts: 20,260
    edited 2009-12-21 17:25
    I do a Halloween spookhouse every year, and I use a $10 Harbor Freight OOH-GAH horn hidden near the doorbell. Man does that make 'em jump. I use a relay to drive it off a 12V lead-acid gel cell, since it does like lots of current. Have fun!

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    ·"If you build it, they will come."
  • Thomas FletcherThomas Fletcher Posts: 91
    edited 2009-12-21 17:46
    Horn Link
    www.fiammamerica.com/Product.asp?ProductID=156
  • Thomas FletcherThomas Fletcher Posts: 91
    edited 2009-12-21 17:51
    So a relay like this?

    www.allelectronics.com/make-a-store/item/RLY-531/12VDC-SPST-N.O.-RELAY/1.html

    The horn is 12V 5amps.
  • ercoerco Posts: 20,260
    edited 2009-12-21 18:16
    You could use a 12V relay and drive it with your 12V battery, or since the Prop uses 3.3V, so you could want a 5V relay instead, powered off your Prop power supply. Note that the relay coil is operating off 5 volts or 12 volts at low curtrent, while the contacts are switching the 12VDC to your horn at high current. You'll need a bias resistor & switching transistor between the Prop & relay, and a flyback diode on your relay coil, one way to do it is shown in the Basic Stamp FAQ sticky note.

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    ·"If you build it, they will come."
  • Thomas FletcherThomas Fletcher Posts: 91
    edited 2009-12-21 19:04
    thank you.
  • kf4ixmkf4ixm Posts: 529
    edited 2009-12-24 14:46
    Solid state relays are a stamps best friend! i use them alot both in hobby and on the job. they only need a 3-32 volt dc signal to operate, most switch loads up to 280VAC at 40 amps!·and are fairly economical. you can usually find them for between $25-$35, even cheaper if you look around. opto and omron·make alot of them, ive used dayton brand mostly.

    http://www.davis.com/catalog/product_view.asp?sku=6847435&pfx=

    http://www.google.com/products?sourceid=navclient&rlz=1T4ACAW_enUS313US313&q=solid+state+relays+ebay&um=1&ie=UTF-8&ei=toIzS4GnG87GlAeR9qyQBw&sa=X&oi=product_result_group&ct=title&resnum=1&ved=0CB0QrQQwAA

    Post Edited (kf4ixm) : 12/24/2009 3:05:17 PM GMT
  • ercoerco Posts: 20,260
    edited 2009-12-24 19:48
    True, SSRs are great, but they are pricey at $25+. For simple switching apps, I still prefer cheap mechanical relays. They range in price from $5 at radio shack for a 5V spdt unit to dirt cheap online. Ebay is a great source for relays. I stock up on the Aromat/NAIS DIP DPDT relays TF2-5V when I see 'em. They only draw 17 mA at 5V, so a Stamp can drive those directly, no driver transistor required. My last purchase was 100 of them for $32 delivered , so that's 32 cents each. SPST 5V reed relays from the Shack draw 20 mA and also can be driven directly from a Stamp. Always use a flyback diode across the coil to protect your Stamp.

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    ·"If you build it, they will come."
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