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Parallax Omron 12A SPDT Relay question. Coiuld work using 5 Volts instead of 12 V. — Parallax Forums

Parallax Omron 12A SPDT Relay question. Coiuld work using 5 Volts instead of 12 V.

markustermarkuster Posts: 184
edited 2013-06-26 20:08 in General Discussion
Hi,

The Omron 12A SPDT Relay coil works with 12 volts
but I am posting to know if it can work with 5 volts.

Parallax link:
http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/relay/List/0/SortField/4/ProductID/656/Default.aspx

Thanks.

Comments

  • ercoerco Posts: 20,256
    edited 2013-06-21 11:19
    Very doubtful. Possibly down to 8-10 volts, but not 5 reliably. You might find one or two out of a big batch that would work at 5V. There are 5V relays out there. What are you switching? If high current, hopefully not motors or inductive loads.
  • PublisonPublison Posts: 12,366
    edited 2013-06-21 11:23
    erco wrote: »
    Very doubtful. Possibly down to 8-10 volts, but not 5 reliably. You might find one or two out of a big batch that would work at 5V.
    erco is correct.

    The datasheet indicates the "Must Operate Voltage" is 75% of the rated voltage.

    That would put the minimum at around 9 volts.

    Datasheets are your friend. :)
  • Duane C. JohnsonDuane C. Johnson Posts: 955
    edited 2013-06-21 11:35
    Worse yet.
    Even if you find one that may work at low voltage that still isn't a good idea.
    With low voltage the contacts will be closing slowly and depending on the application cause arch damage to the contact.
    If you want to operate at 5V get a relay that has a 5V coil.
    Duane J
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-06-21 12:27
    Not really a good idea.. It might work with 9 or 10 volts, but even then it might wear out sooner due to inadequate pull on the contacts.

    Use a 2n2222 transistor and 12 volt or a bit over 12 volts to drive the coil.

    I use 12 volt relays by preference. There are a lot of good ones with 10 amps or 12 amps capacity.

    5 volt relays tend to NOT go up that high in switching capacity. I find them rather dubious as I like to switch 120VAC with durable relays. I also use the ones that have sockets to wire the 120VAC safely on a DIN rail.
  • ercoerco Posts: 20,256
    edited 2013-06-21 12:34
    Ebay is rife with cheap 5V relay modules (1-8 relays) that are microprocessor-friendly. This unit's relay is stamped 10A at 30VDC, but I wouldn't push it. Max carry current and switching current are two very different specs.

    http://www.ebay.com/itm/1pc-New-1-Channel-Relay-Module-Shield-5V-For-Arduino-ARM-PIC-AVR-DSP-Electronic-/140908985674?pt=LH_DefaultDomain_0&hash=item20ced47d4a#ht_4687wt_849
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2013-06-22 07:50
    No problem driving 12V coils from 5V, all you need is a suitable capacitor to build up 5V on after which you can with the help of a couple of transistors effectively connect the capacitor in series with the relay so 10V is delivered to the coil for a period long enough to pull-in the armature after which 5V is hopefully enough to hold it there.

    But whoa up there, you didn't say what you were trying to do with a relay and the scary part is that you don't even have anything higher than 5V. Have you considered just using a MOSFET or if you are switching mains voltages how about an SSR?
  • TubularTubular Posts: 4,703
    edited 2013-06-22 14:23
    Also, that exact Omron relay series (G2RL) also comes in a 5v coil variant
    http://www.parallax.com/Portals/0/Downloads/docs/prod/compshop/400-00052Datasheet.pdf
  • ercoerco Posts: 20,256
    edited 2013-06-26 20:08
    Tubular wins! :)

    RELAY-ted story: EG has 12V, 20 A (!) SPST relays on sale for 99 cents: http://www.goldmine-elec-products.com/prodinfo.asp?number=G18820
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