okay, so about a month ago i inquired on this forum about constructing a counter that could count both Up and Down in be displayed using a 7-segment LED display. I purchased a few 74192 counters and a few 4511 BCD decoders. My intent is to have the 74192 driven by a 555 timer in monostable mode, that can be switched between the Up and Down inputs (a switch between Ground and Pin 2 would send a pulse to to input of either the Up or Down input of the 74192). The 555 timer is CURRENTLY IN ASTABLE MODE however, until i get the circuit to work properly. The problem is, my circuit's not working
I've constructed Up-counters, using 4026 before and it's a very easy build, however this one is proving much more difficult. It might have to do with the low-active components of the 74192 [opposed to high-active, which is when a high signal triggers the IC (though i'm sure most of you knew that)]. According to the datasheet for the 74192, the input that are not in use want to be kept high, while the few circuits i've seen keep them low). I've tried both arrangements, but to no avail.
When I turn on the circuit (and yes, i'm using a regulated 5V for the enture breadboard) the 7-segment display I have shows "0" but does not change. Also, when i apply Ground to the 4511's Lamp Test (LT) pin, the 7-segment display reads "8" as it should. I know the 555timer works because i've tested it with LED's. It pulses at a rate of about 1000ms High-Low as per its configuration so I doubt that it's the problem. That only leaves the 74192 as the culprit (so basically, I probably have it wired incorrectly). It's current configuration goes as follows:
1: +5V
2: Pin 1 of 4511 (input B)
3: Pin 7 of 4511 (input A)
4: (UP INPUT) held high by 10k resistor (CURRENTLY CONNECTED TO PIN 3 OF 555 TIMER)
5: (DOWN INPUT) held high by 10k resistor
6: Pin 2 of 4511 (input C)
7: Pin 6 of 4511 (input D)
8: GND
9: held high (5V)
10: held high (5V)
11: held high (5V) via 10k resistor
12: (Carry) No Connection
13: (Borrow) No Connection
14: GND via 10k resistor
15: held high (5V)
16: +Vcc
Perhaps i'm holding some high that should be low and/or vice-versa?
Here's the datasheets for the 2 IC's
74192 datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/23048/STMICROELECTRONICS/74192.html
4511 datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/26905/TI/CD4511.html
I currently don't posses and circuit-maker programs, but if somebody thinks that it'd be an easy way to fix this problem, (or at least, allow someone on this board to help me fix this problem), by all means, suggest a decent/free program and I'll get to work. Thanks. -Joe
I've constructed Up-counters, using 4026 before and it's a very easy build, however this one is proving much more difficult. It might have to do with the low-active components of the 74192 [opposed to high-active, which is when a high signal triggers the IC (though i'm sure most of you knew that)]. According to the datasheet for the 74192, the input that are not in use want to be kept high, while the few circuits i've seen keep them low). I've tried both arrangements, but to no avail.
When I turn on the circuit (and yes, i'm using a regulated 5V for the enture breadboard) the 7-segment display I have shows "0" but does not change. Also, when i apply Ground to the 4511's Lamp Test (LT) pin, the 7-segment display reads "8" as it should. I know the 555timer works because i've tested it with LED's. It pulses at a rate of about 1000ms High-Low as per its configuration so I doubt that it's the problem. That only leaves the 74192 as the culprit (so basically, I probably have it wired incorrectly). It's current configuration goes as follows:
1: +5V
2: Pin 1 of 4511 (input B)
3: Pin 7 of 4511 (input A)
4: (UP INPUT) held high by 10k resistor (CURRENTLY CONNECTED TO PIN 3 OF 555 TIMER)
5: (DOWN INPUT) held high by 10k resistor
6: Pin 2 of 4511 (input C)
7: Pin 6 of 4511 (input D)
8: GND
9: held high (5V)
10: held high (5V)
11: held high (5V) via 10k resistor
12: (Carry) No Connection
13: (Borrow) No Connection
14: GND via 10k resistor
15: held high (5V)
16: +Vcc
Perhaps i'm holding some high that should be low and/or vice-versa?
Here's the datasheets for the 2 IC's
74192 datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/23048/STMICROELECTRONICS/74192.html
4511 datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/26905/TI/CD4511.html
I currently don't posses and circuit-maker programs, but if somebody thinks that it'd be an easy way to fix this problem, (or at least, allow someone on this board to help me fix this problem), by all means, suggest a decent/free program and I'll get to work. Thanks. -Joe