Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
The switch control pins of unused switches. of course provide a 0.1 uF cap across the Vcc and Vee of the chipHello:
I am using just 2 bilateral switches of a 4066 Ic. Which unused pins do I need to tied to ground? Do I need to do the same for a LM339 IC ?
Thanks,
The switch control pins of unused switches. of course provide a 0.1 uF cap across the Vcc and Vee of the chip
Only the Control pins, to ground?
Afterall you need to see that the chip doesn't oscillate and created unwanted noise around. Thus keeping the control pin at ground, the concerned gates will be off (high impedance). I hope this is enough.
Thanks. I tied the control pins ...but still the switching is not working. I am trying to substitute what is normally a keyboard switch with the 4066 but it seems the 4066 is oscillating. I am using +5volts , does this makes a difference? Searching on the web I read that 4066 works better at higher voltage , like +9v.
I assume that general filtering of power supply has been done as per standard practice. Then it is necessary and customary to have decoupling caps across Vdd&Vss or Vdd& VeeI liked the words "of course, use a 0.1 uF cap across Vcc and Vee.
That means, people assume everyone knows about noise, "decoupling" or whatever those terms are. I don't. I'm not complaining. I am just thinking I found someone who really knows and this is the time to ask:
I have been working with little PIC LED kits, and they need ZERO caps to keep them working well.
I know this is "on the cheap, and if it works why not?" but I'd like to know a bit more about "best practice" when using caps for noise suppression, etc.
I know that switching outputs can put a load on power sources, so maybe it is a good idea to just stick a cap across the power going to a pic (is 0.1 a "good choice?")
I once made my own scratch built computer board, and the power was oscillating like crazy, until I stuck a very very tiny cap across the input (I think it was) of the 7805 regulator, so I learned by experience a cap can help...
I have been working with little PIC LED kits, and they need ZERO caps to keep them working well.
Often circuits will work without decoupling caps, especially if the voltage source has a very low impedance and is decoupled.
To ensure a circuit will work under all normal conditions, decoupling is recommended.
I know this is "on the cheap, and if it works why not?" but I'd like to know a bit more about "best practice" when using caps for noise suppression, etc.
The best practice is to fit decoupling on the power rails.
I know that switching outputs can put a load on power sources, so maybe it is a good idea to just stick a cap across the power going to a pic (is 0.1 a "good choice?")
I would always add a medium value cap across a power input, say about 47uF thru 470uF, depending upon the type of circuit and psu. Also at least 100nF cap
I once made my own scratch built computer board, and the power was oscillating like crazy, until I stuck a very very tiny cap across the input (I think it was) of the 7805 regulator, so I learned by experience a cap can help...
The datasheet for the 7805 states that they can be unstable and a cap should be fitted on the input and output. Low value caps say 10nF thru 100nF.
Thanks very much, from a very experienced programmer, pretty good digital hacker, but very green "general electronics" person. I just bought my first handful of transistors and diodes and etc to start experimenting, and so far have only done some "Joule Thief" type boost circuits with various inductors I could find. I would LOVE a 'scope to watch what is going on at various points, see what frequency it is running, see at what voltage the transistor conducts, etc. Real basic stuff!
Take care.