Turn power on and off using a Tactile button only?

Thread Starter

Fuji

Joined Nov 8, 2014
100
Is there a simple circuit to allow a tactile button to turn on and off power in a circuit instead of using a relay or old toggle switches?
 

KJ6EAD

Joined Apr 30, 2011
1,581
Yes. They're called a latch circuit, sometimes a flip-flop, toggle or bistable. There are many ways to build them and which you choose will depend on the load voltage and current and on how you prioritize the factors such as cost, size, component count, etc.
 

ErnieM

Joined Apr 24, 2011
8,296
Turn on and off what circuit?

I did this when I needed a simple low (zero was the goal) power way to turn on and off a battery powered device. I used a low dropout regulator that had an enable pin. The tact switch would enable the LDO then the circuit would hold that pin on while it did its thing.

It was most helpful here that the circuit was microcontroller controlled, but I don't think that is essential.
 

MikeML

Joined Oct 2, 2009
5,444
I have some very small mechanically-latching on-off push switches that have a red flag to indicate on. They are ideal for battery powered equipment because they take no power in the off state. I don't remember where I got them....

Allelectronics seems to have plenty to choose from...
 
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alfacliff

Joined Dec 13, 2013
2,458
tactile switches are used mosltly as on off switches in microprocessor operated devices like mobile radios from icom, yeasu and such. the work as an input to the processor to start up the radio with a relay. those radios pull current all the time to keep the processor running. any kind of latch ic would have to be pulling power to recognise the switch was pushed.
 

wayneh

Joined Sep 9, 2010
17,168
I recently fixed an appliance (a wine chiller) that uses capacitance switches under a glass control panel. No moving parts. The part I though was cool was that the switches (sensors?) were mounted on the PCB but had springs to hold them firmly against the glass. Nice solution that eliminates trying to fit them by positioning the PCB relative to the glass. Using the springs allowed a sloppy fit without ruining the function of the switches.
 

Thread Starter

Fuji

Joined Nov 8, 2014
100

KMoffett

Joined Dec 19, 2007
2,918
The concept is not just a toggle switch function, but also a power switch. Logic toggle functions need to be continuous powered...unless you've found a link to one that doesn't. ?

Ken
 

Thread Starter

Fuji

Joined Nov 8, 2014
100
The concept is not just a toggle switch function, but also a power switch. Logic toggle functions need to be continuous powered...unless you've found a link to one that doesn't. ?

Ken
Thanks for the reply!

Are you speaking similar to SR Logic gate? That one looks like it needs to be continuously powered.

There is a few latching toggle switch schematics I found here using logic gates, i might have to use fets or mosfets with it. A bistable logic needs continuous power as well?

http://www.mosaic-industries.com/em...n-switch-turn-on/latching-toggle-power-switch
 
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