Monostable -> Astable -> 4017

Thread Starter

edwardholmes91

Joined Feb 25, 2013
210
Hey Everyone,

Just a really quick question. I am making an electronic dice and I originally had an astable at 5kHz going into a 4017 that cycles through 1 - 6. When you let go your dice lands on a number.

I wanted to extend it so that when you press and it will cycle at a slower speed for a set adjustable amount of time. I therefore added a monostable into the mix and it works great.

The only problem is that the circuit now goes for a set amount of time regardless of how long you press the buttons. Is there a way of making the circuit cycle when the button is pressed and then continue for an amount of time?

Probably a really stupid question, but worth asking a figures before I actually etched the board.
 

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Dodgydave

Joined Jun 22, 2012
11,303
Yes put an electrolytic capacitor across the push switch say 10uF and add a 100K preset in series with the 1K resistor (R6) on the Enable pin, that should give you a time delay of upto 10seconds.
 
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Ron H

Joined Apr 14, 2005
7,063
Attached is one way to do extend the duration of your switch signal.
Use your 555 oscillator as on your schematic. Add the additional circuitry in the attachment to your switch. It consists of a resistor and a capacitor.
The 4017 will count as long as the button is pressed, and for a while afterward. The extra time is determined by R1 and C1.
 

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Thread Starter

edwardholmes91

Joined Feb 25, 2013
210
What I'm looking for is to get the counter to sequence as it is while the button is pressed and then when it's released start the monostable if that makes sense? At the moment it only cycles for the amount of time on the monostable regardless of how long you press and hold a button.
 

LDC3

Joined Apr 27, 2013
924
You will want to connect the switch to the RC circuit to either charge it or to discharge it, so when you release the switch the 555 will be on until the RC turns it off.
BTW, remember to debounce the switch.
 

Ron H

Joined Apr 14, 2005
7,063
What I'm looking for is to get the counter to sequence as it is while the button is pressed and then when it's released start the monostable if that makes sense? At the moment it only cycles for the amount of time on the monostable regardless of how long you press and hold a button.
Dodgy Dave is right. You don't need the CD40106. I'm editing my previous post.
 
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