Maker Pro
Maker Pro

Help with Binary Counter circuit - Doesn't seem to respond to clock.

T

Tony Brooks

Jan 1, 1970
0
Hi All,
I am new to world of electronics and have embarked on a project of building an 8 bit computer. I am following the videos of Ben Eater on youtube. I have learnt a lot so far and have a good understanding but have hit a road block on my second module 'the binary counter'. I have followed Ben's build video (
) and have reach around 4 minutes in when he gets the counter to start counting. This is where things stopped and I saw no counting on the leds. I purchased the sn74ls161an 4 bit counter and the sn74ls245n bus reciever which are both texas instruments ics. I have checked the datasheets and they match what Ben is using. I have attached a picture of the circuit on my breadboard with some labels of components. The clock I built works well but when I attached the clock to pin 2 of the sn74ls161 nothing happens. I can't see anything I have mispinned and power is going to the circuit (a steady 5v). Ive even tried moved some of the inputs to highs and lows to see if this changes anythings. I only have one sn74ls161 so can not test to see if the ic is the issue. Any help would be most welcome.
Thanks
Tony
 

Attachments

  • Binary Counter.jpg
    Binary Counter.jpg
    163.5 KB · Views: 119

Audioguru

Sep 24, 2016
3,656
Joined
Sep 24, 2016
Messages
3,656
Each of the old fashioned TTL ICs needs a power supply decoupling capacitor mounted very close to it.
Your circuit has no capacitors, no schematic and nothing showing a clock oscillator.
 

Harald Kapp

Moderator
Moderator
Nov 17, 2011
13,760
Joined
Nov 17, 2011
Messages
13,760
Your LEDs really should have series resistors for current limiting.
Is the clock generator's ground connected to ground of the circuit?
It is cumbersome to identify teh circuit from an actual breadboard. Show us a schematic diagram of your circuit (example).

One quick observation: It seems pin 19 of the 74245 is connected to Vcc (5V). Have a look at the datasheeet: Pin 19 is the /OE input and needs to be connected to logic low level (aka ground) for the outputs to be active.
 
Top