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• Dimming the LED blinkers

  Mario Gianota • 2 days ago • 0 comments

  The LED blinkers were much too bright, so I have increased the resistance to 1K Ohms. They look much nicer now and don't hurt my eyes when I look at them.
  

• A bounceless and noise free clock is required

  Mario Gianota • 2 days ago • 0 comments

  I have discovered yet another error in the schematic. The crystal oscillator input to the 1 Hertz clock must be bounceless and noise free. The circuit amounts to an RC circuit consisting of a couple of resistors, a couple of tiny capacitors and the crystal itself. I have found the required circuit in a book written in the 1980s. I'll change the schematic as soon as I can and show you the correct circuit. I can't believe there is this much work in such a simple clock, but there is.
  

• Project delayed for approx 30 days

  Mario Gianota • 4 days ago • 0 comments

  I am using the wrong kind of ripple binary counter (the CD4060BE in the schematic). I spent a frustrating day trying to find the fault with the breadboard hookup. Anyway, I eventually found the problem and have found a chip that will do what I expect it to do (I think it will, but you know how it is.). The supplier is in China so I will have to wait about 30 days for delivery. As soon as it arrives I will be able to quickly test the counter reset logic for hours, minutes and seconds. The new binary counter chip is a CD4020B. Despite this problem I am confident that the project is proceeding nicely.
  

• LED Blinkers

  Mario Gianota • 01/09/2021 at 20:06 • 0 comments

  The LED blinkers sit between the 7 segment LED displays and blink on and off at 1 Hertz. The circuit in the video tests them. They appear to be working fine (as far as I can tell). They are driven by a 74HC365 buffer chip that I purchased from Ebay at an extortionate cost. The top board provides the 1 Hertz clock signal to the buffer chip.
  

• Component shysters

  Mario Gianota • 01/05/2021 at 02:49 • 1 comment

  Discovered I need to buffer the LED blinkers with a non-inverting hex buffer. Searched everywhere on the Internet for a CD4050E, found one on Ebay and was charged an unbelievable £3.99 for *one* chip. I ordered it and sent the guy a rude message :D
  

• Testing The 1Hz Signal Generator

  Mario Gianota • 01/04/2021 at 00:39 • 0 comments

  
  

  It took a while (several hours actually), but I finally got the 1Hz signal generator working on the breadboard. There was only one minor error in the schematic (see links) which I have corrected. I still don't have a oscilloscope to test the signal frequency, but the LED appears to blink in time with a digital clock that I have so I am fairly confident. I guess I will have to wait for the clock to be fully assembled and then see how well it keeps time.
  

• Project resumed

  Mario Gianota • 01/03/2021 at 18:37 • 0 comments

  I have built the 1Hz clock signal generator on breadboards, but I suspect that the value of the resistor used isn't accurate enough. I am using a 470K resistor instead of a 330K resistor. I have ordered some 330K resistors from Ebay and I will resume work in a five days, or so. It took me hours to discover this problem. *sheesh*
  

• Project Resumed

  Mario Gianota • 01/03/2021 at 14:25 • 0 comments

  Okay. I know I said earlier that I was going to abandon the project, but I have reviewed the schematics and have decided that I have put too much work into their production to abandon the project. I need to build all modules on breadboards and fully test them to verify the schematic. This may take some time. I will test the 1 Hertz Clock first. Stay with me guys if you are following: I will get a PCB out at some point in the near future.
  

• 7 Segment Counters Circuit Tested

  Mario Gianota • 12/01/2020 at 14:15 • 0 comments

   I built a small test circuit for the CD4026 decade counters and 7 segment LEDs and connected it up to Ben Eater's clock, which I built a while ago. All good, everything worked.

  Next up: build the 1Hz crystal oscillator test circuit. After that, the counter logic reset circuitry needs to be tested and then I will be ready to move to PCB.
  

• Waiting For Components

  Mario Gianota • 11/27/2020 at 10:07 • 0 comments

  I have ordered a bunch of resistors from Ali Express and am waiting for them to be delivered. Some components are coming from Ebay and I will be able to build a few test circuits on breadboard to verify the schematic. I am reasonably happy with the schematic, but of course I have no idea if it works until I build the test circuits.
  

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