All Questions
64
questions
1
vote
2
answers
66
views
Designing a particular clock cycle series with glue logic/CMOS/TTL for serial data without a uP
I am looking to design an interface for serial data that runs for 31 cycles (not 32, I know), but with uneven cycles to transmit serial data. Each cycle is 8 clock pulses (at 7MHz). For the first 20 ...
3
votes
1
answer
356
views
Using a function generator as a clock source to drive several ICs (CD4000 CMOS series & 74 TTL)
I am building a circuit that uses a 4 MHz reference carrier. The used ICs are basically XOR 7486 and NOT 7404, CD4013 flip-flop, etc.
I have a function generator which is capable of providing up to 5 ...
1
vote
3
answers
149
views
Converting a 74LS74 and a 74LS193 to CMOS. What inputs need pullups and what needs pulldowns
I have a circuit I traced out off an old, dead PCB that came from the early 90s. It was using TTL chips back then. One thing I noticed is that it has a dual flip-flop. One flip-flop is being used as a ...
- 67
0
votes
2
answers
99
views
Need help identifying circuit diagram symbol
In the datasheet for Hamamatsu s13131-1536 CMOS line sensor(https://www.hamamatsu.com/content/dam/hamamatsu-photonics/sites/documents/99_SALES_LIBRARY/ssd/s13131-1536_kmpd1159e.pdf) there is this ...
2
votes
2
answers
406
views
3V oscillator to 5V µC with an 74HCT inverter (12.8 MHz) - bad idea?
I'd like to use an AVR (ATmega328P-AU to be precise) in combination with a fairly accurate oscillator for timing purposes. I stumbled upon the fact that oscillators which have greater accuracy mostly ...
- 33
0
votes
1
answer
67
views
Is AM29F040B CMOS EEPROM TTL Compatible
I can't really make any sense of the datasheet regarding whether the AM29F040B EEPROM can be used with TTL inputs, so wanted to ask on here.
It is a 5V CMOS IC, but there are mentions in the datasheet ...
- 1,535
2
votes
4
answers
339
views
What is the correct maximum value for resistor R₁?
How do I calculate the maximum value of resistor R1 if the following values are known:
VDD = 5 V
inverter CMOS CD4069UB
IIL = IIH = 0 mA
VOH = 4.95 V
VOL = 0.5 V
IOH = IOL = 0.6 mA
VD = 1 V
maximum ...
- 121
0
votes
0
answers
86
views
J-K flip-flops TTL to CMOS
The following uses 3 TTL 74SLS76N J-K flip-flops, which are active low:
However, I'm trying to figure out what the settings for the PR and CLR inputs would be using CMOS CD4027 J-K flip-flops. For ...
- 57
0
votes
0
answers
149
views
Could I have a whole batch of bad AT26C16 EEPROM chips?
I am in TTL chip heaven (India) where I can get these things for pennies on the dollar, so I bought batches of chips to tinker with. Among them a 16 AT28C16 EEPROMs, looking like new, and then 2 very ...
- 1,541
2
votes
4
answers
235
views
74xxx logic. Cheapest, most space saving way to invert 10 logic outputs
Please see this circuit.
I'm trying to design a circuit that allows you to use a single button to increment a counter from 0 to 9 (then it will loop). Diode logic will convert the 10 logic outputs to ...
- 309
1
vote
1
answer
2k
views
What are the output logic levels of this STM32?
I am struggling getting my head around the input and output logic levels, mostly the output levels of this STM32 (STM32F446xC/E).
This table shows the output logic levels as dependent on if it is a ...
- 161
0
votes
1
answer
164
views
74f269 counter getting very hot
Hi I'm a DIY enthusiast and I got stuck with the circuit that I designed.
The counter is getting very hot from the moment It's powered up.
In my setup the 330Ohm resistors at the outputs are ...
- 21
2
votes
1
answer
344
views
Combining CMOS and TTL with drivers and Leds with relay driver
I need some practical advice on how to combine different component types.
I designed a circuit with at the heart an up/down counter (74f269) The outputs of the counter are connect to via 330 ohm ...
- 21
0
votes
0
answers
96
views
DC>DC Isolated Converter (ADuM5401)
I'm in a bit of a quandary as to if I've approached something the right way or if there's an obvious solution I'm missing.
(Sorry for lack of schematic, still WIP).
Goal:
Self-powered isolated USB >...
- 1
0
votes
1
answer
712
views
CMOS vs TTL power and impedance
I need to compare and contrast a CMOS IC with a TTL IC. I've chosen a quad 2 input NAND gate IC, 7400 for the ttl version and 4011 for the CMOS. I'm having a bit of trouble with 2 of the requirements.
...
- 21