Are my cd4510 counters connected correctly?

Thread Starter

Arjune

Joined Jan 6, 2018
176
Is my 59 to 00 counters for a clock connected without anomalies. I am concerned about timing and rising or falling logic levels causing the count not to be 60 changes per minute or seconds. I attached a pdf scanned file of the schematic I made on paper. I use an OR gate, 2*cd4510, AND gates and Inverters and a power supply of about 7 volts from an AC adapter with switchable voltages (3V-12V). I don't have an oscilloscope and don't think I know how to use one for checking the clock compared to outputs states. Upon observation, with 4 leds connected to outputs of both cd4510 with 1Kohm resistors, it looks fine but I doubt my abilities. Can those outputs only handle 3mA.
 

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MrChips

Joined Oct 2, 2009
24,623
I stated in another post recently, don't use an output as a logic source if you are already driving LEDs. Drive the LEDs using a buffer. In your case, use CMOS inverters.
LED Output.png
 

AnalogKid

Joined Aug 1, 2013
9,494
Looks pretty good. * * * * for going all discrete.

I see that when counting down, you detect a roll-under from 00 to 99 by testing the upper digit 8 output, which always is invalid, and using it to load a 59 into the counters. Can't you use a similar shortcut when counting up? In your schematic you decode a 60 and use that to force a reset to 00. But don't you only need to decode the upper digit 6? Anytime the upper digit is 6 when up-counting, all lower digit values are equally invalid. This eliminates 4 AND gates and 4 inverters.

If you want to stay with decoding the full 60, you can eliminate a lot of gates if you detect the lower digit 0 with four diodes, a 10 K resistor, and an inverter. This eliminates three inverters and three AND gates.

The 4510 is not intended for direct drive of a display, but it should make enough current for your LEDs to at least be visible enough to confirm that your circuit is working. If you need more output current, a ULN2803/04 has 8 excellent LED drivers in one package.

Where are you located? Is this for school, work, or fun?

ak
 
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Thread Starter

Arjune

Joined Jan 6, 2018
176
I stated in another post recently, don't use an output as a logic source if you are already driving LEDs. Drive the LEDs using a buffer. In your case, use CMOS inverters.
View attachment 143143
The output voltage at Q of the cd4510 only drops a little with the LEDs (less than 1 volt). TTL ICs use more current and the operating voltage is limited. If I do pursue the clock, I plan to use the cd4511 and drive 7 segment displays. I just didn't have room on the breadboard to assemble them. My vision is not that good; I will have a problem to assemble the circuit on a pre-drilled board with contacts close together during soldering. I don't have the skill like I used to to make a printed circuit board using an etch-resist pen. I am sure I see reality with my mind and not my eyes. My eyes appear dead.
 

Thread Starter

Arjune

Joined Jan 6, 2018
176
Looks pretty good. * * * * for going all discrete.

I see that when counting down, you detect a roll-under from 00 to 99 by testing the upper digit 8 output, which always is invalid, and using it to load a 59 into the counters. Can't you use a similar shortcut when counting up? In your schematic you decode a 60 and use that to force a reset to 00. But don't you only need to decode the upper digit 6? Anytime the upper digit is 6 when up-counting, all lower digit values are equally invalid. This eliminates 4 AND gates and 4 inverters.

If you want to stay with decoding the full 60, you can eliminate a lot of gates if you detect the lower digit 0 with four diodes, a 10 K resistor, and an inverter. This eliminates three inverters and three AND gates.

The 4510 is not intended for direct drive of a display, but it should make enough current for your LEDs to at least be visible enough to confirm that your circuit is working. If you need more output current, a ULN2803/04 has 8 excellent LED drivers in one package.

Where are you located? Is this for school, work, or fun?

ak
I am suspicious of your confidence. It seems there may be an attempt to change the polarity of thought to change my gender using the circuit scenario. Since I am a schizophrenic, I feel the need to be honest although I am applying paranoia.
 

Thread Starter

Arjune

Joined Jan 6, 2018
176
Analog Kid; are you talking about an 4 input AND gate using diodes with an inverter to detect the lower 0. You are saying that will eliminate the 4 inverters and 3 AND gates? I don't think the logic will work. 20180107_143135.jpg
 

AnalogKid

Joined Aug 1, 2013
9,494
With an inverter connected to the output Z, this circuit becomes a NOR gate, which is the equivalent of an inverted input AND gate (DeMorgan's Theorem).

ak
 

Ronald Arjune

Joined Apr 28, 2016
17
With an inverter connected to the output Z, this circuit becomes a NOR gate, which is the equivalent of an inverted input AND gate (DeMorgan's Theorem).

ak
I think I believe it now AK. I could use 4 diodes and an inverter and that would replace the 4 inverters and the three AND Gates. I see the logic now. Thank you-I will try it. Can you please tell me how you made the schematic because I don't want to be using paper and pencil.
 

AnalogKid

Joined Aug 1, 2013
9,494
I think I believe it now AK. I could use 4 diodes and an inverter and that would replace the 4 inverters and the three AND Gates. I see the logic now. Thank you-I will try it. Can you please tell me how you made the schematic because I don't want to be using paper and pencil.
To replicate your circuit remember that there must be an inverter after the diodes.

I didn't draw that schematic; I found it on the web searching for 'diode-or circuit'.

http://www.circuitstoday.com/logic-gates

ak
 

Thread Starter

Arjune

Joined Jan 6, 2018
176
Analog Kid I wired the inverted OR gate with the 4 diodes, a 10k resistor to ground and a 4049 inverter and the circuit worked. This saved me gates and would simplify wiring. Thank you very much for your insight.
 

Thread Starter

Arjune

Joined Jan 6, 2018
176
My mod 12 counter is working and I plan to connect it to the mod 60 counter to make a clock. I will use 4 diodes and a resistor to ground with an inverter at the output to replace the 4 inverters and 3 AND gates as Analog Kid suggested. Will I be able to just connect the OR gate pictured between both the mod 60 and 12 for the circuit to work (up and down)? clock interfaced .png
 

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