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Another 5v latching relay source — Parallax Forums

Another 5v latching relay source

LoopyBytelooseLoopyByteloose Posts: 12,537
edited 2013-05-01 01:08 in General Discussion
I know Ero likes to buy these for 99 cents from Electronic Goldmine, but there are times when those are sold out.

http://www.futurlec.com/Relays/LATCHREL5Vpr.shtml

It took a bit of argument to convince people that these are in some ways better than regular relays (like they don't require constant power to hold an on or off), but they do make some low power projects easier to build.

Comments

  • CuriousOneCuriousOne Posts: 931
    edited 2013-03-25 12:16
    quite often, additional specific circuitry needed to operate such relays, cancels all their advantages.
  • localrogerlocalroger Posts: 3,451
    edited 2013-03-25 12:21
    The last batch of latchers I got from erco's supplier had one coil and required reversing the polarity for set and reset, which did complicate the driving and made it impossible to add quench diodes. These have two coils making them much easier to use.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-03-25 23:44
    Frankly, these are two coil latching relays; while Erco had located one coil latching relays that he confirmed work with 3.3v Propeller i/o directly. I'd prefer to use those as no additional circuitry for use with the Propeller is required.

    On the other hand, these would work nicely with the BasicStamp BOE to offer extremely low power.

    Why do some have two coils and other have one coil. Generally the two coil latching relays are required to switch higher load. These are rated for 5 amps.
  • ercoerco Posts: 20,256
    edited 2013-03-26 13:58
    The Hasco relays I ran directly off the Prop BoE were not latching, just standard low-current reed relays.

    http://forums.parallax.com/showthread.php/140126-Nice-Relays-for-1.10-ea-Prop-Potential
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-03-26 18:44
    erco wrote: »
    The Hasco relays I ran directly off the Prop BoE were not latching, just standard low-current reed relays.

    http://forums.parallax.com/showthread.php/140126-Nice-Relays-for-1.10-ea-Prop-Potential


    Hmmmm.... okay. Then these 2 coil latching relays might just be a good choice. It is easy enough to drive the 5V coil via a 2n2222 with flyback diodes.

    For my own uses, reed relays are a bit delicate. 5 amps or more suits me.
  • ercoerco Posts: 20,256
    edited 2013-03-27 19:17
    Looks like the Goldmine is fresh out of my favorite Aromat 5V latching relays anyhoo. Good thing I stocked up.

    Now where did I put them? I still have to make a BS1 control 27 relays.
  • tonyp12tonyp12 Posts: 1,951
    edited 2013-04-30 16:41
    This looks like a good driver IC for these latching relays:
    http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/FAN3241TMX/?qs=sGAEpiMZZMtKB4wrjsn3lSqE3QXy0U%2fLgws7q%2fJvbYI%3d
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-05-01 01:08
    That chip may be excellent for larger, more powerful dual coil latching relays.

    The output is rated at 8 VDC minimum and the relay I mentioned is 5VDC --- they are not compatible.

    Large 12v and 24v latching relays do exist. I find it a bit hard to spend $1.50 on a chip to drive a $2.50 relay. While it may be prudent, even necessary.. it seems as if I might be just adding too many chips because I don't properly understand the latching relay.

    The 5v latching relay has 300mw coils, so it seems to need 60ma at 5 volts. That is definetly too high for direct connect to any microcontroller - a transistor or MOSfet is needed on each latch coil to boost available power.
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