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Looking for relay Answered

I have been looking for a relay that will switch with .3 vdc.  The other side is just a 9vdc source but the trigger has to be .3vdc or lower.



I looked for low signal relays and the lowest practical ones I found had a control voltage of .8V http://mouser.com/Semiconductors/Solid-State-Relays/_/N-6gqku?P=1z0x0ld&Keyword=solid+state+relay&FS=True .  What type of application are you looking to use this in.  It seems you would need to amplify the input signal to trigger the relay because 300mV is below the turn on voltage of most switching schemes I can think of.  If you can give me a description of what you're trying to do and what your trigger signal is and I'll see if I can come up with a circuit to activate the relay.

Mischief, Thanks. I ran onto that too. .5 is the lowest for a replay I could find. I am just trying to make this simple. I can breadboard a switching circuit using a transistor and diode. I have a countdown timer. (I have tried a handfull) I am making a lauching system for model rockets. I have my grand daughter working on "our summer project" I need it to take the .3vdc to switch the 9 vdc for the nichrome wire. I have a firing control box but my grand daughter thinks a NASA countdown on a LCD would be cool. Thanks

That is a cool project. If you're using the relay to fire the ignitor you'll need to take the current requirement into consideration when choosing the relay. The solid state relay mentioned here [ http://www.vishay.com/docs/83805/83805.pdf ] is only rated at 350mA for 100ms max. I found a paper that found the current draw of Estes ignitors at about 12A [ http://www.publicmissiles.com/images/IgnitersWhitePaperbyG-Wiz.pdf ](Page 7). The other issue with the mentioned relay is that the LED used to trigger the relay has a forward voltage of 1.26V TYP. I don't think you're going to find a relay with at 300mV activation, solid state or otherwise. It might be a good idea to rethink the triggering method you're using to use a 9-12V electromechanical relay which should be able to handle the current draw of the ignitor. Hope this helps.

I think the only answer is to find a count down timer that has a higher voltage output when it reaches 0. It seems all the ones I have found are in the .5vdc and under. This has to be a specialized timer built to trigger a circuit. My launch control I already built is great and will trigger a full 9dvc @.5 amp well over 100' of 18 gauge speaker wire. I originally built it to control a fireworks display. I have an old mechanical timer I rigged to launch 30 morters in 1 to 5 second intervals. We had a real close nieborhood out in the country. 4 of us would split the cost of the fireworks and put on a decent display with legal fireworks. (We doctored some of them up) Now that I am all grown up, I am teaching my grand daughter rocketry. She saw a video of us launching a 6 ft rocket that reached 6000 feet. She want to build that one first!

Sounds like you have the trigger part worked out well. I don't know what your experience with electronics is but building a countdown timer is a fairly easy project. There are some relatively inexpensive countdown timer or clock kits that would have the appropriate output signal. I found this one [ http://www.hobbyengineering.com/H1257.html ] but there may be other options. Hopefully you can find one that works.

Will something like this S.S. relay work ? http://www.vishay.com/docs/83805/83805.pdf

Looks like that may just be what I need! Thanks!!!!

You're welcome. There are others of that sort, but they may be difficult to get any of them in less then bulk quantities....I don't know, as I haven't tried.

For 300 mV or less, I think you want to look at search results for "low signal relay". You're going to find mostly solid state stuff, and very low current (tens of microamps).