Jason Frame jaz303

I'm trying to design a circuit that will allow a button to trigger only for a single clock pulse. This was my first attempt, using 2 D flip-flops (using Logisim for now):

The button provides the rising edge which loads high into the first flipflop, and Q1 goes high, then second picks this up on the next clock pulse and Q2 will go high. Q2 going high triggers an async reset on the first flipflop, making Q2 go low on the next pulse.

First question - is this sensible? Perhaps there's a much easier way? (if so, ignore the next question :)

Second question - I had a go at designing a real circuit for this but there's a problem. On quad D flipflop ICs the async reset is shared between all flipflops on the chip, so my reset mechanism won't work here (the second flipflop would immediately be reset when Q2 goes high). So I came up with this hack:

	<!DOCTYPE html>

	<html>
	<head>
	<title>Actor</title>
	<script>

	// things i wanted to try but never got round to:
	//
	// - option to make `actor` a single function that is called once per message

	function Foo() {
	this.destructors = [];
	}

	Foo.prototype.bind = function(ele, type, handler) {
	ele.addEventListener(type, handler);
	this.destructors.push(function() {
	ele.removeEventListener(type, handler);
	});
	}

	// I saw this programming style somewhere a while back and liked it.

	function PubSub(subject) {
	var observers = [];

	subject.notify = function() {
	for (var i = 0; i < observers.length; ++i) {
	try {
	observers[i].apply(null, arguments);
	} catch (e) {

	# http://stackoverflow.com/questions/106920/how-can-i-get-source-and-variable-values-in-ruby-tracebacks

	class StandardError
	alias_method :initialize_old, :initialize

	attr_reader :binding

	def initialize(*args)
	initialize_old *args

	// port of this function:
	// https://github.com/openssl/openssl/blob/master/crypto/evp/evp_key.c#L115

	var crypto = require('crypto');

	var passphrase = new Buffer("secretsecretsecret", "utf8");
	var iv = new Buffer("02E2EFAFD7D550A6", "hex");
	var addmd = 0;
	var md_buf = new Buffer(0);

	#ifndef BUFFERPOOL_H
	#define BUFFERPOOL_H

	#include <QObject>

	template <class T, class R = T>
	class ObjectPool
	{
	public:
	ObjectPool(int count)

	function array_diff(foo, bar) {
	var d=[], i=0, j=0;
	foo.sort();
	bar.sort();
	while (i < foo.length && j < bar.length) {
	var l = foo[i], r = bar[j];
	if (l < r) {
	d.push(l);
	i++;
	} else if (l == r) {

	// trying to do this:
	var fn = new Function("foo", "bar", "baz", "return foo + bar + baz;");

	// with arbitrary number of args:
	var args = ["foo", "bar", "baz"];
	var src = "return foo + bar + baz;"

	// with a non-ctor fn i'd do:
	var allArgs = args.slice(0);
	allArgs.push(src);

	def foo(x)
	puts x
	foo(x+1)
	end

	foo 1