LED on-off momentary circuit

Thread Starter

sonicjunki

Joined Nov 15, 2008
2
Hello,

I would like to make a circuit to connect to a momentary switch when pressed A LED stays on when pressed again the LED goes off. I would like to power the 2 LEDs with a 9 volt battery. I have 2 switches in a metal chassis with 2 LEDs, the 2 switches are momentary switches. Sorry for my ignorance but i have no idea where to begin, I do have soldiering skill tho. The only electronics store in my area is the dreaded radio shack.

Thanks so much in advance. Tom
 

Audioguru

Joined Dec 20, 2007
11,248
The easiest circuit uses an inexpensive Cmos Logic inverters IC, the CD4069.
It has 6 inverters inside so it can make 3 circuits.

2 LEDs can be in series then the 270 ohm current-limiting resistor can be 200 ohms.

Connect the inputs of the unused inverters to ground.
 

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Audioguru

Joined Dec 20, 2007
11,248
Click on the thumbnail pic and you will get a nice big pic. Or right-click on the thumbnail pic and open it or save it as a nice big pic.

You posted your e-mail address in a forum where millions of SPAM robots will spread your address to millions of other SPAM robots. Then you will get lots and lots of SPAM. Too bad.
 

Wendy

Joined Mar 24, 2008
23,408
Click on the thumbnail, which brings up a new screen with the pictures address on top.

Highlight and copy this address.

Sandwich the address between {img}{/img} markers. "[]" = "{}"

You can even do it on the same page, like so.



I thought it was pretty neat when I discovered it, so I published it here.
 

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SgtWookie

Joined Jul 17, 2007
22,230
Unfortunately, Radio Shack no longer carries CMOS or TTL logic ICs; just a few analog IC's, transistors, MOSFETs and voltage regulators.

Probably the least expensive place to get small quantities of digital ICs is DigiKey; they will ship (very) small orders via 1st Class mail.

You could also build inverters out of discrete components (transistors, resistors) if you wished to do so.
 

Wendy

Joined Mar 24, 2008
23,408
Didn't we see one using discrete components about a month ago? Come to think of it, AudioGuru published another one about the same time frame. A lot more complex though.
 

defaced

Joined Dec 21, 2006
3
The easiest circuit uses an inexpensive Cmos Logic inverters IC, the CD4069.
It has 6 inverters inside so it can make 3 circuits.
Is there any reason this circuit won't work with a 70LS04? I found the same circuit a couple of places and all specify the CD4069, which I don't have on hand, but I do have a 74LS04 but the circuit is not working on the breadboard.
 

SgtWookie

Joined Jul 17, 2007
22,230
Is there any reason this circuit won't work with a 70LS04? I found the same circuit a couple of places and all specify the CD4069, which I don't have on hand, but I do have a 74LS04 but the circuit is not working on the breadboard.
You know that the 74LS04 requires a 5V supply, and has a much higher current draw than the CD4069 right?

Other than that, if you're powering a red LED that has a Vf of 2v @20mA, replace the 270 Ohm resistor with a 150 Ohm resistor, and it should work.
 
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