LED control circuit

This will probably be easy for you folks who do this all the time and are up on what is available IC wise.

I want to sequence an LED thru modes with a push button. It will sequence like this: on, flash, off, on, flash, off etc.

I would supply steady power and flash power to a bus maybe as there will be a lot of LEDs to control.

Any clever ideas out there?

Many thanks for the help.

Reply to
gstringe
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You didn't say what the flash time is compared to on and off times, but maybe you can use a decade counter like 4017 with 4 counts as 'on', 1 count as 'flash' and the others off?

-Bill

Reply to
wrongaddress

PIC, or eqivalent, microcontroller is a cheap way of doing this if you have the development kit. You could make a simple sequencer out of logic gates.

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Mark
Reply to
qrk

PIC10F200: 63 cents in quantity one from Mouser.

Luhan

Reply to
Luhan

Thanks guys, yes I had thought of the 4017 but in a little different mode. The PIC sounds interesting and of course requires me to learn and exercise my brain. Yeeks!

Lemme splain what I am a doin...This is the 4th system like this I have done in the last 20 years and it is a clinic or Dr. office exam room status system. Wall plate outside room with 3 colored lites and each lite has a double throw switch with center off. So one direction hooks the lamp to the steady power and other direction to the flash power. Each lamp can also be monitored at master status panels at various locations in the clinic if desired. This basic system is really simple, trouble free and if designed properly will last almost forever, cepting bulbs. Well the first three systems I did had incedescent bulbs and this newest one is going to use LEDs so I am toying with the idea of eliminating the switch and going to a lighted pushbutton that combines the functions.

I thought I had retired from this kind of thing but the ole Dr. friend weasled me into one more system. Of course there are a couple of manufacturers that make this stuff but costs have put them out of the ballpark for the Dr. and me being Mr easy....well you know the rest.

Please keep the ideas commin if you think of more.

many thanks,

Reply to
gstringe

I think your basic idea is good. There is a flashing bus, a continuously on bus, and ground.

For each button, there is a counter, which is configured so it resets itself when it gets to 11. So it counts as follows: 00, 01, 10, 00 etc.

These counter outputs go to an analog mux/demux which, according to the input count, selects either the continuous bus, the blinking bus, or ground.

Let me know if you want more detail.

--Mac

Reply to
Mac

Aha, thanks Mac, I had the counter part figured but hadn't thought long enough about it to come up with the rest. I might think as an example that the outputs of lets say a 4017, one would turn on a transistor fed by the steady bus and the next output would turn on a transistor that was fed by the flash bus and the next one ground...Hmmm not bad thanks for the jog in the brain. The next step is can I make it simpler? Other than size I can't get much lower cost than a 4017, two transistors and a pushbutton. Right now I have three switches & three LEDs mounted on a single gang electric cover plate. Might get crowded. Could also put the control circuitry at a central place with the power supply. Why do I get myself into these things ;-)

Reply to
gstringe

You could do this:

1)Run a clock at twice the blink rate into a D flip-flop. 2) Lets assume a 0 at the Q output corresponds to LED ON. 3) with SET and RESET (aka PRESET) inactive, the LED will blink at 1/2 the clock frequency. 4) With the SET lead a 0, the LED will be OFF. 5) With the RESET lead a 0, the LED will be ON.

Control the thing with a 3 bit shift register. Use 1-1/2 dual D flip flops that powers up in state 011 ( the leftover stage is your D flip flop that connects to the LED). Connect the Q of the third stage to the serial input. Connect the push button (debounced) to the SR clock input. Connect the Q of the first stage to the RESET of the Dff,. Connect the Q of the third stage to the SET of the Dff.

To power up in state 011, connect the RESET of the first SR and the SET of the other two SRs to a 22K resistor that goes to VCC, and a 10 uFd capacitor that goes to GND.

Tam

Reply to
Tam/WB2TT

And $100.00 for the development kit, and 6 months to learn to program the damn thing.

Just build a 3-stage Johnson counter, where step 1 is "ON", step 2 is "flash", which you can do with a 555 or a couple of transistors and some discretes, and "Off."

What's the real problem?

Good Luck! Rich

Reply to
Rich Grise

On Fri, 19 May 2006 05:32:03 -0700, gstringe wrote: ...

Welcome to the world of consulting! ;-)

Cheers! Rich

Reply to
Rich Grise

Bite the bullet and use a micro! I'd use a small Atmel AVR microprocessor such as ATtiny13 (8 pin dip with internal oscillator) for around $1.50, download the free evaluation version of CodeVisionAVR from www.hpinfotech.ro which is code size limited but won't effect you for this app, buy a cheap programmer (ATAVRISP MK II), and write your program in C using the example programs as a guide. Go on, it'll be worth it! As an aside, CoveVisionAVR is one of the best and easiest to use C compilers I've come across - inexpensive, feature packed and very well supported. Worth paying for the full Standard version IMO. The AVR is also very much suited to C code. Buffer up the output with N-MOSFETs such as 2N7002 or use logic buffers.

Mark.

Reply to
markp

Because it's fun! One other thing you need to consider. If you're using long wires to connect pushbuttons to your circuitry, using all these nice logic gates means you may need to protect the inputs that connect to pushbuttons from static and remote lightening strikes. A series resistor and pair of diodes will work. Don't forget to debounce your pushbutton.

vcc | - ^ | pushbutton----R----+---gate input | - ^ | gnd

--
qrk
Reply to
qrk

--
Geez, it\'s all so simple, isn\'t it?

But... I don\'t see a schematic.
 Click to see the full signature
Reply to
John Fields

Well, it's not .basics, after all - how hard is it to look up "johnson ring counter" on google?

Thanks, Rich

Reply to
Rich Grise

Great thoughts and ideas folks.. I didn't expect this much help..again many thanks

Reply to
gstringe

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