Connecting two LEDS to a button without Micro controller or PIC? Is that possible?

I am making a card that will include two LEDs on the front. Simple greeting card and nothing fancy because of time constraints. Is there a way to include a button without a micro controller or PIC? Since it is a card including those things may be bulky. Any ideas? Thanks!

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bwrussell5 years ago
Design a circuit that runs the LEDs (power source, resistors, LEDs) and then but the button in their somewhere it will break the circuit. A button is just a type of switch. I don't know how you plan to deploy this circuit on the card but the type of switch, toggle or momentary, is going to make a big difference.
wolfsheim_lvr1 (author)  bwrussell5 years ago
What kind of switch would you suggest? Would putting any type of switch break the circuit? I am not quite sure how I am going to deploy the circuit yet because I am not sure where to put the button (switch).
Circuit
The attached picture is the most basic circuit that will work. The switch doesn't have to be where i placed it, it can be anywhere in the circuit.

Switch selection
First off you want a SPST (Single Pole, Single Throw) switch, assuming you want both LEDs to turn on and off together. That means it has one input and one output  and has 2 positions, on and off.
The decision between toggle and momentary depends on how you want the circuit to function. Toggle is what most people think of when you say switch. The light switches in your home are toggle, when you turn them on or of they stay that way.
Momentary switches start either on or off and when you push them they change but when you take your finger off they they don't stay. Think about a machine gun trigger, normally it is off, not firing, when you pull the trigger it is on, firing, but when you take your finger off the trigger returns to it's original position and it is off, not firing.

If you use a toggle it will be off when you send/give the card. When the person receives the card they will have to push the button/switch to turn on the LEDs. This could be fine if the card says press here or something of the sort.
If you use a momentary switch it can be set so that while the car is closed the switch is pressed and off and when the card is opened the switch is released and the LEDs turn on. That would be a "spst press off momentary switch".

Check the "Related" side bar to the right ----------->
it looks like it has several instructables describing what you want to do.
Simple switch circuit.jpg
wolfsheim_lvr1 (author)  bwrussell5 years ago
Thank you! That was very informative. I went over to radio shack and purchased:

-2.5mm High Tact Switch which says is SPST 50mA 12VDC

-SPST Momentary Submini Pushbutton Switch 0.5A 125VAC/250VAC

-Detect Switch which is SPST and is momentary 1mA - 5VDC

The Detect and Tact Switch are much smaller and easily hidden for the project I am making. Though the Detect and Submini have two prongs (+ and - ?) and the tact has five.

Which one, in your opinion, would work with the wonderful diagram that you provided?
IMG_20120208_195508.jpgIMG_20120208_195523.jpgIMG_20120208_195537.jpgIMG_20120208_195456.jpg
I would say that the detect switch is your best bet but only if it turns the circuit off when the switch is pushed in. You are going to want to build a test version of your circuit before you build the final one in the card to make sure everything works like it is supposed to.
Switches normally don't have + or - specific legs. A switch simply breaks the circuit so it doesn't matter which way it goes. Just orient it the the direction that works best for triggering the switch when and how you ant it to trigger.

The tact switch is different because it is a surface mount component (SMT) meaning it was designed to be mounted on a circuit board. It doesn't have to be used like that though it can though if needed. As far as having multiple leads there should be two that are input and two that are output. You should only need to connect to one pin on each side and just leave the other two legs empty. As far as the fifth leg i would hazard a guess that it might be a ground pin or just a empty pin for connecting it to the circuit board or an extra input or output depending on which way it goes in the circuit.

Sorry about the torrent of information, I hope it's not making things more confusing.
wolfsheim_lvr1 (author)  bwrussell5 years ago
Thank you so much for the torrent of information! I am not confused one bit. I feel much more knowledgeable about what I am making. I don't think I could thank you enough for your help.

I am going to try and build the test version tonight and if I come up on a snag Ill be sure to mention it. If that's okay with you?
Of course it's ok. That's what this site is all about.
wolfsheim_lvr1 (author)  bwrussell5 years ago
I've run into some confusion. I have 2 super bright LEDS (probably overkill but that is what I have available) that are 3.2 volts/piece I believe. I want to use a CR2032 Cell battery which is only 3 volts.

I bought two CR2032 battery holders and I am not sure how to connect the two so there is enough power. How would i connect two battery holders to one switch ad two LEDS? Or do I have to use two batteries?

In a series I would need two, could I use parallel with using only one battery?

I did a simple version using the detect switch and it worked but that was with only one LED and no resistor.
When batteries are in series you add the voltage (3+3=6V). When batteries are in parallel you add the current but keep the voltage the same (3V). Also a battery holder without a battery does you no good.

If you don't provide the full forward voltage to the LEDs they will not be as bright. With two 3.2V LEDs and one 3 V battery in series you will be woefully under voltage and have very dim LEDs. If you put the LEDs in parallel the voltage will be fine but i don't think a 2032 has a high enough discharge current to drive both LEDs. You could try but even if it works it will drain the battery twice as fast.

You need to at least use two batteries with everything in series and no resistor. Optimally you would have three batteries and a 130 Ohm resistor with everything in series or get two identical LEDs with a combined forward voltage <6V, two batteries, and a matching resistor.
wolfsheim_lvr1 (author)  bwrussell5 years ago
I apologize for not specifying but I have several 2032 batteries as well as the holders and a 130 Ohm resistor.

How would you connect more than one battery together? That is where my confusion mostly lies. Do you connect them together with wires and electrical tape? That is one reason I bought the holders so it might be easier to attach them but I am not sure how to go about linking the batteries together.
Ah I see, sorry about that. Just wire the positive terminal from the first battery (B1) to the negative terminal of B2 and repeat with B2 and B3. The best way would be to solder wires between each terminal. If you can manage to connect them with electrical tape that is fine.
wolfsheim_lvr1 (author)  bwrussell5 years ago
Thank you so much for your help! It didn't work out in time for the gift.

When I connected the two LEDs to the batteries they would light up, but when I added the switch it would stop working. I thought it was because of the connection so I soldered it to see if it would work and it didn't.

I am going to keep working on it but I just wanted to say thanks again.
Sorry to hear that. Spitballing possible solutions: replace the switch it may be bad for some reason, flip the wires on the switch.

Actually looking back if you are still using the detect switch it is only rated for 5v. More than one of the batteries you are using in series is more than that. Try a different switch with a higher voltage rating and see if that works.
Thermionic5 years ago
Both on at the same time? Yes. One on, one off, yes. Connect them in parallel or series with appropriate resistors and the button. Also, a Pic IS A microcontroller.