Simplest 2-LED alternating flasher

Well you have imposed quite a few restrictions. Maybe look at multivibrator circuits.

--
If you successfully got the LED to drive the counter, then this
should work: (View in Courier)

                           +V
                            |
                           [R]
                            |
                          [LED]
                            |
                            D
FROM 4017 CLOCK INPUT>----G
                            S
                            |
                           GND

Does the clock input go high when the flashing led is off? If it does connect a LED to the clk input and to GND... something like this maybe...

VCC + | | .-. | | | | '-' | | | V -> Flashing LED - LED | .--o--. |-| | === | R Q| GND '--o--'

Sorry, I didn't mean I want it related to a 4017. This is a completely separate exercise. I was just noting that I have successfully used a flashing LED to drive a 4017. My circuit was published in Australian Silicon Chip magazine in about 2004.

I now just want to make 2 LEDs flash. Need it quickly so was hoping for a solution without having to experiment.

"Peter" wrote in news: snipped-for-privacy@h3g2000cwc.googlegroups.com:

Take a look at this:

Oh, btw, when you need it fast it's best not to ask on Usenet... Searching on the internet can get you results in less than 5 minutes. ;-)

Puckdropper

--
Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm

I did search the web but found nothing. That circuit you referred to contains about 10 more components than I want to use. That looks like a standard astable multivibrator for which I agree there are thousands of circuits on the web. I am looking for something a bit unique.

The traditional method is an astable version of the classic 2 transistor flipflop. If you want anything simpler, with fewer components (2x transistors, a couple of caps & a few resistors), & more unique than that, you're going to have to design something yourself. (There's any number of ways of flashing two LEDs with a single chip, but I can't think of any that are simpler than a 555.)

--
   W  "Some people are alive only because it is illegal to kill them."
 . | ,. w ,      
  \\|/  \\|/              Perna condita delenda est
---^----^---------------------------------------------------------------

---

1. When you reply to a post, don't snip all of the post you're replying to, because that way no one knows what you're replying to.

1. When you reply to a post that you've left some of the poster's text in for context, don't top post. So far you haven't been able to, but if you snip properly you probably will want to since you're a Google Grouper. For heaven's sake, read their stuff on posting to USENET.

2. Pay attention when you read what someone gives you.

For example, I posted:

"If you successfully got the LED to drive the counter, then this should work: (View in Courier)

+V | [R] | [LED] | D FROM 4017 CLOCK INPUT>----G S | GND"

Notice that the gate of the MOSFET is connected to the 4017 input, which is also the output of the circuit you used to drive the 4017.

Since you didn't show the circuit, one would have to guess how it was put together, but since you _know_ how it was put together all you need to do is connect the point driving the counter to the gate of the MOSFET.

So, to get your 2 flashing LED circuit all you need is the LED flashing circuit you already have and the one I've given you.

Maybe this'll make it easier:

+V | [R] | [LED] | FROM THE PART OF THE D FLASHING LED CIRCUIT------G 2N7000 WHICH WAS CONNECTED TO S THE 4017 CLOCK INPUT | GND

-- JF

Oh, ick! 2N3055s to flash LEDs? OP could use 2N2222s, PN2222s, 2N3904s,

2N4401s - practically any general-purpose tranny that will take the supply voltage and maybe 25 mA. They're so common you could almost find them lying in the street. ;-)

Here's a sort of generic thing on astables:

Have Fun! Rich

---+--------+---- 5V | | | [220R] self- | | flashing V .---+ LED T / | | |/ | +-| V ordinary | |\\| T LED | ~\\ | | | | [1K] | | | | | ----+----+---+- 0V

you may not need the 1K resistor.

Bye. Jasen