My Simple Scoreboard - Need help.

alec_t said:

Your cap values are still way too low. Make them 10uF. You can also eliminate R1, R2 and R18 because the 74LS14 has internal 20k pull-up resistors. You will then have a debounce time-constant of 200ms, resulting in the '14 input being held below the upper Schmitt threshold for ~80ms, considerably greater than likely switch bounce duration.
I've no idea what those voltages relate to, but the Vf of a red LED is typically in the range 1.8V-2V. You still haven't said which LEDs you will be using. White LEDs, for example, have a typical Vf > 3V. For a 12V supply, Vf = 2V and 4 LEDs in series the current through them will be ~33mA, which is excessive if typical red LEDs (rated 30mA max) are going to be used.
To blank a leading zero.
Not understood.

Click to expand...

alec_t said:

The first circuit will work; the second won't.

Click to expand...

BeerBelly said:

It doesn't have the switch debouncing. Get yourself a plug type breadboard and experiment a little bit. There is allot more to it than a piece of a schematic;
Voltage regulation, bypass caps, wire length, construction practices
Even with us seasoned hobby builders there are unforeseen bugs.

Let us know how it works out.

Click to expand...

I just have to order the components now from the UK and get them here in the Balkans.

Click to expand...

alec_t said:

So why is your Location in your posts given as 'UK' ?

Edit: BB's reference to bypass caps reminds me: each IC should have a 100nF ceramic cap connected across its supply pins as close to the IC as possible.

Click to expand...