Simple counter/clock

Details

Counting circuit consists of modified astable multivibrator circuit with three NAND, master-slave data flip flops connected as series toggle flip flops, thus I have 4-bit counter. The dtl gates have LEDs instead of pairs of conventional diodes to slightly save on part count and cost. In addition, this scheme provides visuals for gate working.

Files

DSC_0849.jpg

Elements of counter and decoder are stacked and wired together.

JPEG Image - 759.65 kB - 04/14/2017 at 04:42

Preview

Components

14 × Yellow LEDs

28 × Red LEDs

2 × Green LEDs

3 × Blue LEDs

224 × Diodes 1N4148

Project Logs

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Finished!
Pavel • 04/22/2017 at 08:00 • 1 comment

The thing is now complete and working!
Solution is found!
Pavel • 04/20/2017 at 03:56 • 0 comments

The humble diode AND was not to blame after all, it was prior wiring that was faulty.
Here are simplified schematics with voltages:
1) original wiring:
collector of Q1 was wired directly to base of Q2, to achieve second inversion, thus making buffer; simultaneously from the same collector was the tap to the AND gate of decoder, as inverted input. Failed. the solution was to make this into two full-fledged invertors, and after this modification all started to work as it was intended to.
2) corrected wiring:
Problem with output logic levels
Pavel • 04/14/2017 at 04:51 • 0 comments

For decoder I used simplest diode 4AND logic gates (image), assuming they would work properly, and give +Vcc for high and 0.6V for low.
Unfortunately, output for HIGH is measly 1.6-1.7V and it is too low for driving display unit.
I am still cannot understand, why is it so.