Switch question

Not easily. What are you controlling, and from what kind of power supply? Is this a homework question?

It's easy (if you use logic parts)...

Debounce the switch.

Clock a D-flop (QN connected to D) with the debounced signal.

Use Q or QN to operate a logic level MOSFET to do the actual power switching.

Probably can also do it with a multi-pole relay.

...Jim Thompson

no it's not homework, it's just curiosity.. i'm basically wanting an LED light to turn on and off by touching the button.. just a small part of a larger system that i'm working on. The test circuit will receive 3VDC

If that's from a battery, then CMOS would be a good choice. Well, you'll need low voltage CMOS, but I think 3V is available. You could use a stock type D f/f chip as mentioned, then add a transistor to drive the LED and anything else. Hmm..what color is the LED? 3V isn't much headroom for even a green LED.

Tim

none none scrobe on the papyrus:

I would put in an 8-pin PIC or AVR (ATtiny13 would be ideal). The button goes to one of the I/O pins and the other five can be used to control the LED and other stuff as well. Cost's pennies and you'll learn a bit about software along the way.

OK, build Jim Thompson's flip-flop circuit, and make sure the switch is debounced.

Is your pushbutton SPDT by any chance? If so, a much simpler solution can be made using an R-S flip-flop made from two NAND or NOR gates.

Yes... you get the debouncing without adding any parts, and you get the full output capability of the AVR, which is enough to drive an LED.

On Sun, 18 Jun 2006 15:46:40 -0400, "mc" Gave us:

Some idiot up in avd is "laughing" because he thinks that the fact that Toshiba's new HD DVD player has a PC like motherboard in it, a flash drive, A LAN connection, and runs Linux, makes it a PC.

I guess those Windows CE refrigerators are PCs too then...

That is NOT a SPST action. An ordinary pushswitch IS ALREADY a SPST device.

You are instead requesting an ALTERNATE ACTION pushbutton.

Use two inverters, two resistors, and a capacitor.

See the ALTERNATE PUSHBUTTON cameo in my CMOS Cookbook.

Like in a flashlight to turn the bulb on?

Call the input of the first CMOS inverter A, its output B Call the input of the second CMOS inverter C, its output D

Connect B to C directly. Connect D to A via a 4.7 k resistor, forming a set-reset latch.

Add a series 470K resistor and 0.1 uFd capacitor to ground at point BC with the capacitor end being grounded. Call the resistor capacitor junction E.

Wire the pushbutton directly between A and E.

This is one of the simplest possible relalizations of a master slave type T flip flow.

It is, of course, self-debouncing.

More in

Has that been done yet?

Even worse are the students who assume everything has *always* had a CPU. What kind of CPU is in a 1950s radio? :)

(And those who use the word "fifties" to denote approximately 1925-75. The "fifties" do not comprise the Nixon or Hoover presidencies, nor WWII, nor the Beatles...)

if

button

Duck tape.

Not to my knowledge, but it was the most extreme overkill I could come up with in under five seconds. ;-)

Sure, the 8048 came out just before 1950, wasn't it? ;-)

Nixon was in office in the '50s ('53-'61), BTW. Hoovers sucked then too.

use a flip flop if your using a SPST type botton.

Eh?

'53-'61 would be about right for Nixon as Eisenhower's VP, but he was President from 1969-1974. See...

...Jim Thompson

A CPU controlled LED flashlight is ridiculously more efficient than a conventional one.

Also MUCH cheaper in the long run.

I was thinking about the traditional incandescent lamp type of flashlight with more mechanical parts than electrical.