electronically set, manual reset relay

event and only restart after a button is pushed, even if the restart is tried one year later. I want to do it all solid state so a small, low power, (

Hi, Harry:-

I don't suppose you want to think about microcontrollers with EEPROM or FRAM..

Dual-coil latching relays such as Panasonic's TQ series are a pretty reasonable solution. Small, and they only need a few millisecond pulse at 30mA-ish 5V to set and reset.

Wow. Avionics _and_ safety-related (at least it sounds like). You may want to consider any certification requirements _before_ you build an "oops, gotta redesign" into your product.

Pay attention to vibration specs, too.

event and only restart after a button is pushed, even if the restart is tried one year later. I want to do it all solid state so a small, low power, (

--- if you want to build one, this should work: (View with a fixed-pitch font)

-- JF

event and only restart after a button is pushed, even if the restart is tried one year later. I want to do it all solid state so a small, low power, (>

event and only restart after a button is pushed, even if the restart is tried one year later. I want to do it all solid state so a small, low power, (>

It's not HD's first design to go into an aircraft.

The vibration specs are pretty sensible on latching relays- I'm putting them into aircraft as well. From what I can see, application of (non-shock) G-forces that would cause the relay to flip will mean that a new aircraft and crew will be also be required.

Best regards, Spehro Pefhany

The "hold for a year or whatever" was making me read an implied "with power applied or not".

If the OP doesn't mind it only working for as long as power is applied, a simple SR flip-flop to a relay coil would do the trick.

Point taken -- sometimes I forget to look at names.

:)

event and only restart after a button is pushed, even if the restart is tried one year later. I want to do it all solid state so a small, low power, (

Is there going to be power there? Do you need power to maintain this?

You can magnetic latching relays, we use them at work and they work great.

You can employ a simple bimetal NC thermo sensor that can be used to trigger the relay in the off position and then use a button when ever to reset it back to the on position.

If plain on using power then what happens when the power goes out? I guess you could have a simple latching circuit that would latch on in the even of over heat and if power is lost, it'll just turn off and when power is restored and if the heat is still up there, it can then relatch the circuit again. In which case, a CMOS 555 timer would work great because it operates on low voltage and low power. It has a trigger input that can be used for the over temp sensor. Once that is triggered once it'll stay latched. The trigger input can be the restart of it.

Jamie

Yup sure would. a 555 :) only 8 pins used and can directly drive a relay coil if needed..

Jamie

"Harry D" wrote in message news: snipped-for-privacy@googlegroups.com... Working on an avionic design. I must turn off power at an over temperature event and only restart after a button is pushed, even if the restart is tried one year later. I want to do it all solid state so a small, low power, (

On a sunny day (Thu, 23 Aug 2012 13:13:15 -0700 (PDT)) it happened Harry D wrote in :

A SWITCH!!!

event and only restart after a button is pushed, even if the restart is tried one year later. I want to do it all solid state so a small, low power, (

The classical aircraft thingy is a breaker. Just make it trip.

=20

com

com

Hi Seph, thanks for those kind words. After posting this I came up with a s= imple circuit using TQ SMD Relays. One IC, push button switch, single coil = latching relay and a monster MOSFET. The TQ relay is rated for +85C but we = must operate at 70C ambient. Can I get a similar relay at 105C? Your G forc= e comments are very helpful. Yes, the latch must remain set for long not po= wered periods. Cheers, Harry

simple circuit using TQ SMD Relays. One IC, push button switch, single coil latching relay and a monster MOSFET. The TQ relay is rated for +85C but we must operate at 70C ambient. Can I get a similar relay at 105C? Your G force comments are very helpful. Yes, the latch must remain set for long not powered periods.

Will power always be present at the time of a valid reset?

RL

Hi, Harry:-

IIRC some vaguely similar relays are available in special "H" insulation versions (but maybe not the latching types).

In this case you might want to consider a hermetic Teledyne $$$ relay such as these ones:

The commercial version is $200+, but it's small, hermetic and good for

Hey, here's one that's probably a lot more reasonably priced and maybe more available:

erature event and only restart after a button is pushed, even if the restar= t is tried one year later. I want to do it all solid state so a small, low = power, (

remote operated circuit breaker ?

-Lasse

Google should find plenty of latching relays if you search for their common names: bistable relay or Carpenter relay.

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Those relays look good but need 0.5W to 2.0W of coil power to latch. The ot= her you suggested needed