optimal binary counter required

[mstechca]

Right now, I have a cmos 4040 counter and a 74HC393 binary counter.
There are other counters I could buy, but I won't buy them until I can see that they can simplify my design.

I'm asking for a counter, because I have discovered that my last ROM programmer failed to work 1/2 the time, and if I pick better counter(s), then maybe I won't have to make my tracks so narrow.

I want to know what counter(s) I should use. I'm dealing with a single-sided board, and I can't go too much lower than 0.6mm or I will risk breaking the track with the soldering iron. Also, I want to avoid wire jumpers as much as possible.

Basically my ROM programmer has counters interfacing to the 28C64.

Until I get a good answer, I will have to try to come up with something.

Seems that the PCB is the hardest part about the circuit, especially when I don't have professional tools.

And if audioguru thinks I make "toy" radios, wait until he sees my "toy drill" :lol:

 

[Papabravo]

I'm a bit puzzled by your post. How would you define better counters? What method will you use to evaluate the alternatives? If your ROM programmer is failing 1/2 the time I would look at your programming voltage waveforms for compliance with the manufacturers specifications on voltage level(s), current limits, rise time, fall time and so forth.

Second point. A counter is a counter. It needs a clean clock signal. It has setup and hold times for clear and load. What exactly do you suspect to be the fault with your counters? I'm guessing double counting on a single clock pulse. Have you looked at your clock waveform on a scope?

A 4040 is a very tolerant device. Along with the 4060 you are not likely to find that many bits in such a small package. I used them very successfully in my ROM programmer that I built in 1977. It was a wire wrap affair, but I spent an inordinate amount of time on the Vpp generation and wave shaping.

 

[Nigel Goodwin]

I'm a bit puzzled by your post.

If you'd been here longer you wouldn't be! 8)

 

[ljcox]

Papabravo's advice is good.

The 4000 series CMOS is slower than the 74HC series, so as he wrote, you need to check whether the rise and fall times are adequate.

Are there any mechanical switches in the circuit? If so, you may have a contact bounce problem.

 

[Papabravo]

Fan?

Nigel,

mstechca fan, are you?

:wink:

 

[mstechca]

Re: Fan?

Nigel,
mstechca fan, are you?
:wink:

ha no :lol: :shock:

I'm a bit puzzled by your post. How would you define better counters? What method will you use to evaluate the alternatives?

I'm hoping for a counter that helps provide optimal PCB layout.
There are too many devices that don't allow optimal PCB layouts.
Have you tried connecting a 74HC373 with a complex chip on a single-sided PCB without jumpers? I don't think so.

 

[Papabravo]

mstechca

I guess I don't screw around with considerations like that because I don't have to. It's de minimus as far as I'm concerned.

 

[audioguru]

MStechca,
Maybe your counter's failure is due to inadequate supply bypassing. If you are using a 555 as an oscillator then its 400mA supply spikes each time its output switches requires suitable supply bypassing to hold up the supply voltage, and the counters need supply bypass caps as well.
The datasheet for the LM555 recommends a 0.1uF (ceramic) plus a 1uF electrolytic. I always use a 0.1uF ceramic disc cap supply bypass cap very close to each Cmos counter IC and for every few gates ICs.