I am building a counter circuit using a SN74HC161 4-bit binary counter to turn on certain LEDs as the counter counts up. The counter should count up each time the push button is pressed. Is my wiring diagram correct for this application, or am I missing something?

 

Yes, you should probably use anti-bounce input.

And you need to tie down/up ABCD inputs.

 

Welcome to AAC!

am I missing something?

You need a pull-down resistor on the clock input; otherwise it floats when the switch is opened.

You need a switch debounce circuit.

If you care about power dissipation, you shouldn't let the preset inputs float; even if you're not using them.

 

For future reference here is a GUI solution where no user code has to
be written. Example attached. Note no transistors used for LEDs, the
output pins can drive enough current unless you are using high wattage
LEDs.

Tool and Compiler is free, PSOC Creator.

Lots of other capability in part, see attached component list.

Board is $ 4, re-programmable, lots of logic, analog, ARM core if
you decide to do some coding.

Component list attached. A component is on onchip resource in PSOC. PSOC 4 family is a subset of
this list, 5LP family (and its $ 10 board) has virtually all.


Regards, Dana.

 

Welcome to AAC!
You need a pull-down resistor on the clock input; otherwise it floats when the switch is opened.

You need a switch debounce circuit.

If you care about power dissipation, you shouldn't let the preset inputs float; even if you're not using them.

So I should add a pull down resistor to the CLK input and ground A through D?
And what do I need to do for the switch denounce circuit?

 

In the most simple form, add a capacitor across the pull down resistor. For example, a 47K resistor and 1 uF capacitor combine to have a 50 ms (millisecond) time constant, a good starting point given that we know nothing about the switch or why it is being pushed. Add the two components in parallel between pin 2 and pin 8.

YES, ground pins 3, 4, 5, 6 if they are unused.

ak

 

In the most simple form, add a capacitor across the pull down resistor. For example, a 47K resistor and 1 uF capacitor combine to have a 50 ms (millisecond) time constant, a good starting point given that we know nothing about the switch or why it is being pushed. Add the two components in parallel between pin 2 and pin 8.

YES, ground pins 3, 4, 5, 6 if they are unused.

ak

 

The circuit is being used to change the color of an RGB LED each time a push button is pressed. The voltage source is 5V. What values should I use for the resistor and capacitor?

 

For example, a 47K resistor and 1 uF capacitor combine to have a 50 ms (millisecond) time constant, a good starting point

ak

 

ak

Here is my updated circuit. Should this work now?

 

No.

add a capacitor across the pull down resistor.

ak

 

No.

ak

Oh my bad. Like this?

 

Yes.

ak

 

Yes.

ak

Thank you so much! Sorry for all the questions.

 

One final question, is it possible to make the counter reset itself so that the LED turns off once it cycles through all of the colors?

 

One final question, is it possible to make the counter reset itself so that the LED turns off once it cycles through all of the colors?

What do you mean by reset? The LEDs will cycle through 8 different combinations endlessly. One of those combinations is all LEDs off.

 

What I meant was, at first, the LED should be off, then once the button is pressed, it turns on, and the color changes with each pressing of the button. Once the last color/count is reached, pressing the button should turn the LED off. Pressing it again after it has turned off should turn the LED back on, allowing you to cycle through the combinations. The problem I'm having right now is that the counter is counting up once power is applied to the circuit before the push button has been pressed.

 

The problem I'm having right now is that the counter is counting up once power is applied to the circuit before the push button has been pressed.

Well, that isn't what you said in post #15.

You need to have a power on reset on CLR if you want to force the counter to power up with a count of 0. You can use a resistor and capacitor to hold CLR low when power is first applied.

 

Well, that isn't what you said in post #15.

You need to have a power on reset on CLR if you want to force the counter to power up with a count of 0. You can use a resistor and capacitor to hold CLR low when power is first applied.

Oh! Thank you!