Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

"CD-player type" pushbutton control

Status
Not open for further replies.

Jimbo

New Member
Hello all,

for one of my designs, I wanted to create the type of button that is found on just about every piece of electronic equipment today, for example the CD-track selection button on CD players (hence the message title, as I don't know the "offical" name of such a switch).

It works as follows: push and immediately release the button, you get one output pulse (and the CD-track number is incremented by one). Push and hold the button for about a second, and you get a pulse train (and the CD-track numbers increments automatically).

What I've made up to now is a button which simultaniously drives a monostable and an astable vibrator (actually using 2 555ers as I had heaps lying around). The 'start' of the astable vibrator is delayed by a relatively huge RC-network to get my one-second delay (with an LM324 as comparator to trigger the start). The outputs of both vibrators are then simply joined trough diodes.

I felt this solution was wasting components (even if I replace the 555ers with transistor-based vibrators, I still need two vibrators), so I wanted something better.

Second idea (which was never created) was to simply drive one astable vibrator with the switch, but that gives the 'time-base' problem: the frequency of this vibrator will never be faster than the 'hold'-time, because the RC values never change. In effect: the delay after the first pulse will be exactly the same as the delay after all other pulses, but that is not what I want. The pulse train needs to speed up after hold, or in (an attempt at) wave forms:

Code:
..........__________________________________________
button:___|                                         |____________
..........._ 	        _     _     _	  _	_
output: __| |__________| |___| |___| |___| |___| |________________

So basically I am stuck. How would you lot go about designing a "CD-player button"?[/code]
 

Sebi

Active Member
Here is a sematic, the output same as You drawed.
 

Attachments

  • bounce.GIF
    bounce.GIF
    3.5 KB · Views: 376

Roff

Well-Known Member
Here's a way you can use a 555, if you don't mind that the first pulse stays high for a long time, like this:
 

Attachments

  • long_1st_pulse.gif
    long_1st_pulse.gif
    5.7 KB · Views: 354
  • output.gif
    output.gif
    2.1 KB · Views: 360

nettron1000

New Member
Wouldnt a dedicated microcontroller be a bit of overkill for this rather simple application ?
 
Status
Not open for further replies.

Latest threads

Top