Re: Shift Register 74LS166


sillycar@xxxxxxxxx wrote:
cbarn24050@xxxxxxx wrote:


it seems from your last answer that you are using push buttons to drive
the logic high. TTL pulls high by default so you would need pull down
resistors on each input. Supply voltage is also critical for lsttl,
within 250mV of 5V, a decoupling capacitor (0.1uF) at the chips supply
pins is needed as well. Check your logic levels, you need less that
0.8V for low and more than 2V for high.
- Clock is set at 40 Hz as i need a relatively fast timing for my
application.


I inserted 100 ohm resistors between each pushbutton and ground, the
other leg of the pushbutton goes to the supply line to prevent
overloading of current into the chip. Can this be considered as a pull
down resistor as well? I have not inserted a decoupling capacitor
though. Does this mean i just to insert a capacitor between the power
supply and the supply pin of the shift register ie. Pin 16? Does this
capacitor apply to all other supply pins
of other chips as well eg. Schmitt Trigger and Inverter? Thanks.

Don Lancaster wrote some good books especially for beginners. The TTL
Cookbook,
CMOS cookbook and Active Filter cookbooks are in my 'DO NOT GET RID OF'
pile along with some older National and Motorola databooks. You will
not regret getting Don's books. He explains, with minimum pain, how to
do what you're attempting. I learned a lot from Don.

BTW, Thanks Don !

Glenn Gundlach

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