where to find a pulse relay

[igeorge]

I have a thermostat project which run from 2AA batteries
The microprocessor has a minimum consumption current
In fact the whole project run in just 1-2 miliamps.
The big issue is the output of thermostat.
Most thermostats, to conserve power , and change the battery maybe once a year , use latching relays.
2 coils take too pins from micro
1 coil is complicated to drive
I heard about pulse relays. One pulse = ON; take the power out and still ON, like a latching relay. Next pulse, on the same line, turn it OFF.
I found circuits to drive 1 coil latching relays, but most of them use capacitors, which of course will drain my battery
I need a suggestion of a manufacturer for this PULSE relays.
Contacts 2 A, coil 5-12 VDC
Thanks

 

[MikeMl]

Do you require the isolation that a relay provides? If isolation is not an issue, and you are switching DC or AC, modern NFETs will switch 2A of load current with almost zero power into their gate(s) circuit and only requires one port pin to control it.

 

[Tony Stewart]

Magnetic Reed relays have an effective current ratio from coil to contact ranging from 200 to 1000 but very ! expensive above 300 depending on voltage ratings.
Latching magnetic relays are much less ~<=100 using 2 coils

Toggle Relays would have no feedback with one connection and I have not seen these.

Your best bet is to use a MOSFET switch and if source is 24Vac ( typ) then use a full diode bridge and cap between source and MOSFET.

 

[MikeMl]

Magnetic Reed relays ...

But a reed relay requires constant power to the coil, which would kill his battery. A magnet-biased reed relay requires no standby power, but requires an H-Bridge (likely two port pins) to pulse it...

 

[granddad]

This help... **broken link removed**

 

[KeepItSimpleStupid]

What you want is an "impulse relay" https://www.digikey.com/product-detail/en/S89R5DAC1-12/S89R5DAC1-12-ND Too expensive and too big.

 

[MikeMl]

This help... **broken link removed**

No, because the relay coil is continuously powered, killing the TS's battery quickly.

 

[granddad]

Not so ... MikeMI To quote the article .. what is described is a single coil latching relay.
Battery life is good since the load is only 400uA –there is no relay coil current in either the On or Off states.

 

[Tony Stewart]

What you want is an "impulse relay" http://www.digikey.com/product-detail/en/S89R5DAC1-12/S89R5DAC1-12-ND Too expensive and too big.

also too power hungry
Bipolar single coil relay takes 300mW @3V **broken link removed**
or **broken link removed**

But MOSFET and AC bridge still a better deal.

But you must state load explicitly in terms of AC DC resistive or inductive , voltage & current.