Hey,

I am doing a little bit of design to make a speaker/preamp selector... I
know there's a simple digital circuit where you have a momentary contact
pushbutton as the input, and the output flops between 0 and 5 volts with
each push of the button. Can anyone with a better memory than me recall
exactly what this circuit is?

Thanks

Max

Max Holubitsky wrote:
Hey,

I am doing a little bit of design to make a speaker/preamp selector... I
know there's a simple digital circuit where you have a momentary contact
pushbutton as the input, and the output flops between 0 and 5 volts with
each push of the button. Can anyone with a better memory than me recall
exactly what this circuit is?

Thanks

Max


Type D flipflop. 4013.

Ze Nith wrote:


Max Holubitsky wrote:

Hey,

I am doing a little bit of design to make a speaker/preamp selector... I
know there's a simple digital circuit where you have a momentary contact
pushbutton as the input, and the output flops between 0 and 5 volts with
each push of the button. Can anyone with a better memory than me recall
exactly what this circuit is?

Thanks

Max


Type D flipflop. 4013.

Except, that since the button will "bounce" many times before it settles
in on 0, or 5V, this circuit will need to be a bit more complicated.

-Chuck

Chuck Harris wrote:
Ze Nith wrote:



Max Holubitsky wrote:

Hey,

I am doing a little bit of design to make a speaker/preamp selector... I
know there's a simple digital circuit where you have a momentary contact
pushbutton as the input, and the output flops between 0 and 5 volts with
each push of the button. Can anyone with a better memory than me recall
exactly what this circuit is?

Thanks

Max


Type D flipflop. 4013.


Except, that since the button will "bounce" many times before it settles
in on 0, or 5V, this circuit will need to be a bit more complicated.

-Chuck


Yes. 10k resistor in series with switch, .1 uF capacitor to ground at IC
input.

Ze Nith wrote:


Chuck Harris wrote:

Ze Nith wrote:



Max Holubitsky wrote:

Hey,

I am doing a little bit of design to make a speaker/preamp
selector... I
know there's a simple digital circuit where you have a momentary
contact
pushbutton as the input, and the output flops between 0 and 5 volts
with
each push of the button. Can anyone with a better memory than me recall
exactly what this circuit is?

Thanks

Max


Type D flipflop. 4013.



Except, that since the button will "bounce" many times before it settles
in on 0, or 5V, this circuit will need to be a bit more complicated.

-Chuck


Yes. 10k resistor in series with switch, .1 uF capacitor to ground at IC
input.

4000 series CMOS tends to get really ****ed off if the input slew rate
is very slow. It will sometimes go into SCR latch up, and short the
power supply connection to ground, and go POOF!

-Chuck

Hi:

How about setting up your mechanical switch to drive a one-shot with
appropriate timing characteristics which then drives your flip-flop?

--
Steve

Using a one-shot is a good way to do the job.

The point I was attempting to make is you must not clock the FF with
a mechanical switch directly, and you must also make sure that CMOS
inputs have a rapid slew rate. If the slew rate is slow as the input
passes through the 50% mark where both the P and the N channel fets
are conducting, there is a current glitch that happens which can
activate some of the parasitic transistors that live on an IC's die,
and these transistors will permenantly go into conduction, just like a
triggered SCR. If this happens, the parasitic transistors will short
Vss to Vdd until the CMOS chip's guts vaporize. The manufacturers try
really hard to prevent these SCR latchups from happening, but they still
do under certain circumstances.

-Chuck

Steve wrote:
Hi:

How about setting up your mechanical switch to drive a one-shot with
appropriate timing characteristics which then drives your flip-flop?

--
Steve