Logic Outputs Problem in 7493 IC

[marconi]

Earlier on, in your frequency counter post, we covered the unsuitability of diode resistor logic for AND or OR when used to detect a counter state and generate a very fast rise/fall and short duration reset pulse to RO1 and RO2 of the 7493. Because of the capacitance between anode and cathode of the diodes the circuit is too slow to produce one short clean reset pulse. Do you remember now? We had to use a semiconductor AND/NAND ic from the 74 or 40 series.

 

[_q12x_]

I managed to make this thing work in reality !

The (right) 4 logic probes here in the image are LEDs in reality, counting in binary.
This setup here is the same as the diodes one (but way more complicated)
The only problem is that I dont have any other 7430. This was the only one. And is most probably a slow TTL version, very old and made by romanians somewhere in 80's. The good news is that everything is working. Well, until the end of these 4 lines.
I just measured all the Buss lines and all the outputs and inputs and I pretty much get the same result as with the diode version.
VERY STRAAAAAAAAAAAAAAAAANGE!!!!!!!!!!!!
The only difference now, is that I can use those 4 leds counting in binary on the buss line.
But everything is UNDETECTABLE on those 4 bus lines !!! yet, it is working.
AGAIN> VERY STRAAAAAAAAAAAAAAAAANGE !!!!!!!!!!!!
Why I cant measure them? I still get a very WEAK signal, close to gnd.
Maybe I dont know how to measure this thing? How in the hell are you measure such thing?
AGAIN> VERY STRAAAAAAAAAAAAAAAAANGE !!!!!!!!!!!! WOW.

 

[_q12x_]

 

[marconi]

Good news. Thank you for the update. You have my suggestion for providing source and sink logic signals to your dtl logic gates to try out.

 

[_q12x_]

Indeed, and thank you that you watched my movie.
I just revert back to the diodes instead of the 8 input NAND and it is working....but for certain counts. Up to count to 8 everything works. But AFTER 8, is giving me errors. So the diodes not good in the logic side. I put back the 8 input NAND and tested every count. And I get this result:

Which is great news. Also the binary counting leds are doing their jobs fine, and also for the moment that single #1 module display also did it's job for everything so far.
I was thinking to replace this 4xAND diode gate with a 4input DTL NAND and a NOT also DTL.... But I will see.... What do you think? Should I ?
Next...probably I will have to make all the display #'s and see what 's*it' I will get from there.
This long tutankamon:

This is how is looking now in reality and is also working in the simulator as well with minor changes (R9) and some errors, but is working.
As you can see, no transistors on the BUS. Directly from the 7493 !!! Which Im not really a fan, but, it works.

 

[marconi]

I will check your posts but today and tomorrow I am visiting my elderly parents so I have less time to contribute(?) to your project.

I do not think you will be satisfied unless you test your Dtl logic gates first. You may need the source and sink circuit I sent you a diagram to drive 16 of them.

 

[_q12x_]

Im on the wave !
I managed to make the analogue version of a NAND Gate +a NOT Gate !
Tested from 2 to 16, all working as with the real chips.
Excellent !
Check the picture in the bottom of it.

 

[_q12x_]

 

[_q12x_]

also...

 

[_q12x_]