Keypad BCD Storage Circuit Design


WhatsApp Image 2026-06-07 at 6.46.18 PM

I’m currently out of execution credits, so I can’t inspect or modify the Flux project yet.
From the image, this is a keypad-entry BCD storage circuit: digit keys feed a 74LS147 decimal-to-BCD priority encoder, the encoded BCD outputs are inverted, then clocked into a chain of D flip-flops/latches so multiple entered digits can be stored and sent to BCD display decoders/drivers. There’s also a switch debounce block, a CLEAR/reset line, and pull-ups on the digit inputs.
Current project state:
  • No components placed
  • No nets/wiring
  • Random draft project name still unchanged
  • No schematic work has been executed yet
What remains to build this in Flux:
  1. Identify exact IC choices:
    • 74LS147 or modern CMOS equivalent
    • Inverters, e.g. 74LS04/74HC04
    • D flip-flop packages, likely 74LS74/74HC74 or multi-bit registers
    • Debounce one-shot/timer or Schmitt-trigger debounce circuit
    • BCD-to-7-segment decoder/drivers if displays are included
  2. Create the schematic from the image.
  3. Add power pins, ground, and required decoupling capacitors for every IC.
  4. Add keypad/pushbutton inputs with pull-ups.
  5. Add CLEAR/reset circuitry.
  6. Verify the logic-family compatibility: LS-TTL vs HC/HCT/CMOS matters at 5 V.
  7. Run schematic review and fix any errors before moving to PCB layout.
When credits are available, I can recreate this circuit cleanly in Flux and adapt it for either the original TTL-style design or a more beginner-friendly modern CMOS version.
Choose CMOS version
Find suitable ICs
Explain keypad wiring
Create parts list
No schematic yet

Talk to Flux to get started.