momentary switch question

[gompee]

I know very little about electronics so please bear with me if I sound a little stupid.
How do I use a momentary (tact) switch to turn things on and off. Like led lighting circuits, case fans or what ever. Is there some sort of circut thingy for this.
I am a newbie so some thing simple so I may understand.

 

[Johnson777717]

momentary switches operate with two different options. On and Off. For the On function to work, the user has to press and hold the button down in order to keep the switch on. The moment the user lets go of the button, the switch automatically switches to the off position. The on position of the switch allows current and voltage to be transferred through the switch to a circuit. The off position stops all flow of current and voltage through the switch.

The word momentary tells us that the switch is designed to be used momentarily, or at a single point in time as opposed to being switched on and staying on until the user switches the switch off.

Some common examples of momentary switches are your keyboard keys, or telephone number keys, or your TV remote control buttons.

Most momentary switches are single pole single terminal (SPST). The single pole (SP) tells us that the switch only controls one side of the voltage polarity (Commonly the positive voltage side). This means that the positive supply is connected through the switch. the single terminal (ST) tells us that there is only one terminal for the power to flow through, so there is only two options (off or on). SPST switches will have two pins that the wires will connect to. One pin (either pin) connects to the power supply. The other pin connects to the circuit. So when the button is pressed down and held down, the circuit will receive power from the power supply. Obviously, when the button is released, all power moving through the switch is stopped.

Other configurations of switches are common as well, although most momentary contact switches will be Single terminal.

 

[gompee]

Thanks for your reply mate

I understand how a momentary switch works, what im trying to say is.
How do I make a tact switch operate so that it is allways on or off. (no need to hold the switch down).
Is there some sort of electronic circuit that the tact switch can send a pulse too that will do the actual switching on or off of lights or what ever.

The reason for the use of tact switches is because of the confined space and the fine travel of the button makes the tiny tact switch ideal for my application.

 

[gerty]

The amount of current you are planning to switch on/off has a lot to with what circuit you use..Low current can use a flip flop solid state circuit and high current can use a relay, with multiple poles, to do the job..

 

[Roff]

Do you want to use one switch for on and another switch for off, or do you want to toggle with each press of a single switch (1st push on, 2nd push off, 3rd push on,...)? We can show you how to do either.

What are you trying to switch, i.e., how much current and voltage are you switching?

 

[gompee]

Thanks gerty

my lighting circuits are only using 5v - 12v supply.
Flip Flops?
are there any newbie friendly circuit diagrams for these

 

[gompee]

Hi Ron

yeah Id like to toggle from a single switch

 

[Roff]

Thanks gerty

my lighting circuits are only using 5v - 12v supply.
Flip Flops?
are there any newbie friendly circuit diagrams for these

How much current do your lights draw? This is important!

 

[gerty]

Maybe this'll help..I believe you want the latch circuit..
http://www.discovercircuits.com/B/bistable.htm

If not ,just do a search for 'flip flop circuits'

 

[Roff]

Here's a schematic. Before we can design a driver for your lights, we have to know how much current they draw, and how you want them connected (parallel, series, independent, etc.).

**broken link removed**

CD4013 datasheet

 

[mixos]

Check this out also:

How to make a momentary switch latch
https://www.electronics-lab.com/for...on=display;threadid=538;start=msg2339#msg2339

 

[Roff]

Check this out also:

How to make a momentary switch latch
https://www.electronics-lab.com/for...on=display;threadid=538;start=msg2339#msg2339

Those circuits might not work reliably with some switches and/or some brands of 4013s.

The potential problem with the first schematic is that switch bounce may cause the flip-flop to toggle more than once when the button is pushed, and possibly again when it is released.

The potential problem with the second one is that some (Fairchild), if not all, have a maximum clock rise and fall time spec of from 5 usec to 15 usec depending on supply voltage. The RC filter has a time constant of 10 milliseconds. This doesn't mean that it won't work, but it means that it might not.

My design addresses both these potential problems at the expense of an extra IC.

 

[gompee]

Hey thanks for all your helpfull replys.
I think I may have bitten of more than I can chew here, those circuit diagrams are totally mind blowing to me, they may as well be written in Japanese. But any way.

I have 2 lighting circuits both identical. I have 6 led's connected in parallel and a 15 ohm resistor running off 5v supply.
Here's the spec's for the led's Im using If it helps.
SOURCE MATERIAL:InGaN
EMITTING COLOUR:BLUE
LENS TYPE:WATER CLEAR
LUMINOUS INTENSITY-MCD:3000 TYPICAL/4000MAX
REVERSE VOLTAGE:5.0 V
DC FORWARD VOLTAGE:3.3V TYPICAL
DC FORWARD CURRENT:20mA

 

[Roff]

I've added a driver for your LEDs based on your input. Paralleling LEDs to a single current limiting resistor will result in unequal brightness if they are not well matched. I have shown a separate resistor for each LED, which will potentially give you better intensity matching. The rectangles just delineate the various circuit functions.