My Simple Scoreboard - Need help.

[mihailok]

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.

Hi Alec, I made the alterations as you mentioned to the design. I thought I already changed the Cap Values, but I may have loaded a previous version or not have saved it.

I posted the LED's I had in mind in my second to last post. They are found at this address:
https://uk.rs-online.com/web/p/visible-leds/4966156/
The data for them is as follows: Dominant Wavelength: 630 nm, Forward Voltage: 2.6 V, LED Colours: Red, Luminous Intensity: 5500 mcd.

What I meant for the 74LS14N, it is only one Unit I require for the board. They just use different pins?

 

[BeerBelly]

Get rid of your voltage sources on the left(V4,V5,and V6). They don't belong there.

 

[alec_t]

I agree with BB. The gate inputs should be connected to the caps and switches only (unless you want to include a respective 100Ω resistor in series with each cap to reduce the current through the switch to prolong the switch life).
Sorry, I missed the previous link to the LEDs. I've now checked their datasheet.
Yes, you will need only one 74LS14N for the board. You will also need four 74LS47's (one per digit).

 

[mihailok]

So like this?

Alec, how about like this:

 

[alec_t]

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

 

[mihailok]

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

Great! Thank you so much. Now I just need to order all the components. They shall take a couple of weeks to reach here in the Balkans unfortunately. I am just researching the best way to power the PCB now.

 

[mihailok]

I just saw something similar to what I am doing and found a schematic, which uses a button system like this:


Is this better than the one we devised? It doesn't include the 74LS14N.

 

[BeerBelly]

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.

 

[mihailok]

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.

Thanks BeerBelly, I shall do that. I just have to order the components now from the UK and get them here in the Balkans. Plus the 74 series doesn't look so easily available in the UK, may have to get some parts from the US.

 

[alec_t]

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

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.

 

[mihailok]

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.

Spending a year in the Balkans , my home is in the UK. Ok, I shall add the capacitors now.