Electronic switch

Thread Starter

Dritech

Joined Sep 21, 2011
863
Hi all,

Is there a kind of relay that is latching but without it being supplied continually? (i.e. when supply is given, contact is close. If supply is removed, contact remains closed. When the supply is applied again, the contact will open).

The reason why i want it this way is because i want the system to be low in power consumption as much as possible.
 

Thread Starter

Dritech

Joined Sep 21, 2011
863
But all lutching relays need continuous supply to their input pins to keep the contacts close. Am i right?
 

mcgyvr

Joined Oct 15, 2009
5,394
Don't forget that the "holding current" for a regular relay is typically much less than the pull-in current. Meaning that with a regular relay you can really reduce its power consumption by a method to reduce the current level after the relay has been operated.
Of course its not like a latching relay in that no current is required to keep its state..But you might also have issues with a latching relay in situations where you must ensure its in the correct state after a power loss situation.
 

Thread Starter

Dritech

Joined Sep 21, 2011
863
Hi,

Another question. I am using a 16*4 LCD with blue back-light which will be on 24/7. Does it make sense if i connect a PIR sensor (the one in the link below) with the back light pin so that when the room is empty, the light will turn off therefore consuming less power.

PIR sensor:
http://www.ebay.co.uk/itm/2pcs-Pyroelectric-Infrared-PIR-Motion-Sensor-Detector-Module-DC-4-5V-20V-/290635789956?pt=UK_HomeGarden_Lighting_Lamps_Lighting_SM&hash=item43ab3e3684

LCD:
http://www.ebay.co.uk/itm/16x4-1604-Character-LCD-Module-Blue-Color-LED-Backlight-HD44780-/170755499947?pt=LH_DefaultDomain_0&hash=item27c1d227ab
 

mcgyvr

Joined Oct 15, 2009
5,394
Sure.. but you could also just have the backlight turn off after x amonut of seconds of inactivity. (assuming you have buttons or something to signal a user is actively using it)
 

Thread Starter

Dritech

Joined Sep 21, 2011
863
Hi all,

Regarding the latching relay that i was going to use to reduce power consumption, is it better to use a solid state relay?? Does solid state relays consumes high power ??

Thanks in advance
 
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