Kay said:
Thank you all for pointing out things...I am trying to synchronize 2
devices. I don't know their internal circuits. The only thing I know is that
they are both TTL compatible...74LS90 worked fine for us until recently it
stopped working. I am now on the west coast and only had very basic
electronics. The summer student who is working on this on the east coast
hasn't had any electronics yet. I've ordered more 74LS90 online but not sure
if they can arrive on time. We have some binary counters at hand (74LS93
(x2), 74LS05, 74LS04, 74HC163, 74HCT161E) that's why I want to use binary
counters to build a divide-by-5÷-by-10 circuit. I just figured out how
74LS90 works last night. Now I need to see if I can adapt a binary counter
easily to that...That said, 74LS90 has very limited input voltage range.
I've had static shocks in the lab before so I thought we somehow burnt the
chip. That's why I want a more noise-endurable TTL-compatible family
now...Again, I don't have any electronics textbook at hand right now, and I
only had very basic electronics at school. So the questions I asked might
sound silly.
thanks again,
-Kay
If you have to use the LS93 and the LS05 is available then you can do
something like this:
Please view in a fixed-width font such as Courier.
DIVIDE BY 5
CLK>-----------------------+----------+
TTL | |
IN inverters --- ---
74LS05 \ / \ /
O O
| |
| |
| | 1k
CLK +------------/\/\---+-o Vcc
--- <-+ +--------+--+ | | |
5 | | | | | +--------------+
| | | | | | | |
| | +-RO-RO--CLK--CLK-+ | |
| | | 1 2 B A | | |
| | | | | |
| | | 74LS93 | | |
| | | | | |
| | +-QD--QC--QB---QA-+ | |
| | | | | | |
+---|-------|---+ +---|<|----+ |
| | '4148 | 680 |
| +-----------|<|----+--/\/\--+
| 1k | |
+-----------+--/\/\--------|--------+
| | | |
| | --+-- |
| | '3904 / \ |
| | +----+-e c-----+
| | | | |
o --- --- | 220 |
/ \ \ / \ / +--/\/\-o gnd |
--- O O |
| 1000p | | 1k |
+----||-----+----+------------/\/\--+
| |
| 680 |
+-----------------------------/\/\--+
DIVIDE BY 10
CLK>----------------------------+-----+
TTL | |
IN inverters --- ---
74LS05 \ / \ /
O O
| | 1k
CLK +-------/\/\---+-o Vcc
--- <-+ +--------+--+ | | |
10 | | | | +----|---------+ |
| | | | | | | | |
| | +-RO-RO--CLK--CLK-+ | | |
| | | 1 2 B A | | | |
| | | | | | |
| | | 74LS93 | | | |
| | | | | | |
| | +-QD--QC--QB---QA-+ | | |
| | | | | | | | |
| | | | | +---------+ |
| | | | | | |
+---|-------|---+ +---|<|----+ |
| | '4148 | 680 |
| +-----------|<|----+--/\/\--+
| 1k | |
+-----------+--/\/\--------|--------+
| | | |
| | --+-- |
| | '3904 / \ |
| | +----+-e c-----+
| | | | |
o --- --- | 220 |
/ \ \ / \ / +--/\/\-o gnd |
--- O O |
| 1000p | | 1k |
+----||-----+----+------------/\/\--+
| |
| 680 |
+-----------------------------/\/\--+
DIVIDE BY 5 AND 10
CLK>-----------------------+----------+
TTL | |
IN inverters --- ---
74LS05 \ / \ /
O O
| |
| |
| | 1k
+------------/\/\---+-o Vcc
+--------+--+ | | |
| | | | +--------------+
| | | | | | |
| +-RO-RO--CLK--CLK-+ | |
| | 1 2 B A | | |
| | | | |
| | 74LS93 | | |
| | | | |
| +-QD--QC--QB---QA-+ | |
| | | | | |
+---|-------|---+ +---|<|----+ |
| | | '4148 | 680 |
| | +-----------|<|----+--/\/\--+
| | 1k | |
| +-----------+--/\/\--------|--------+
| | | | |
| | | --+-- |
| | | '3904 / \ |
| | | +----+-e c-----+
| | | | | |
| o --- --- | 220 |
| / \ \ / \ / +--/\/\-o gnd |
| --- O O |
| | 1000p | | 1k |
| +----||-----+----+------------/\/\--+
--- | |
\ / | 680 |
O +-----------------------------/\/\--+
| |
| 1k |
+--------------------------+------/\/\--+
| |
| +-----+--+----+ |
| | | | | |
| | +-RO-RO--CLK--CLK-+
| --- | 1 2 B A |
| gnd | |
| | 74LS93 |
| | |
| +-QD--QC--QB---QA-+
| |
| |
\|/ \|/
CLK CLK
--- ---
5 10
DIVIDE BY 5 OR 10
CLK>----------------------------+-----+
TTL | |
IN inverters --- ---
74LS05 \ / \ /
O O
| | 1k
+--+-------/\/\---+-o Vcc
|5 | | |
SW o | | |
o | | |
CLK <-+ +--------+--+ |\o------------+ |
OUT | | | | | 10 | | | |
| | | | | | | | |
| | +-RO-RO--CLK--CLK-+ | | |
| | | 1 2 B A | | | |
| | | | | | |
| | | 74LS93 | | | |
| | | | | | |
| | +-QD--QC--QB---QA-+ | | |
| | | | | | | | |
| | | | | +---------+ |
| | | | | | |
+---|-------|---+ +---|<|----+ |
| | '4148 | 680 |
| +-----------|<|----+--/\/\--+
| 1k | |
+-----------+--/\/\--------|--------+
| | | |
| | --+-- |
| | '3904 / \ |
| | +----+-e c-----+
| | | | |
o --- --- | 220 |
/ \ \ / \ / +--/\/\-o gnd |
--- O O |
| 1000p | | 1k |
+----||-----+----+------------/\/\--+
| |
| 680 |
+-----------------------------/\/\--+