Electronics Forum / Basics / February 2007

For those who want to see the makeup of a typical R-Core transformer
bobbin I have posted pics on ABSE titled "R-Core bobbin"

this will be my first attempt at formulating a sensible question about
this stuff. you've been warned. here's the question...
unless i've already misinterpreted something (http://
webpages.ursinus.edu/lriley/ref/circuits/img96.gif) the following is

I just finish building a small circuit utilizing an opto coupler, the
mct6.
I use an LM331to translate voltage to frequency, that works, but when
I add the optocoupler in , it do not keep the frequency intact. I mean

I was just wondering what the word "threaded" refers to in the context
of a Threaded Neill-Concelman (TNC) connector.  I know threaded wires
contain thin metallic threads for flexibility, but I don't think this
is what threaded in TNC is talking about.

hello. i wonder if you can help me...
as a newbie, is there someplace where can i find a good explanation of
transistor models? not on the web: i looked all over it, and
everything i found was either

I'd like to set up a walk-in sensor. Something like the things you see
in all those 007 movies. When someone walks through the door,
interrupts a laser-light at foot level.
The thing is, I don't want to spend a lot of money on it.

Exciting opportunity for an Analog Design Engineer
I know you get lots of emails about opportunities, but if only look at
one this should be the one. Our client's compensation program includes
an IC designer royalty program. The IC designer royalty program is

How do you go about choosing a suitable flyback diode for a 1.8kW 36V motor?
Does it have to be able to handle above the motor's stall current of 50A?
Cheers,
Michael

I'm diving back in to discrete component circuit design again after a
few years, and I'm blanking out, is there any functional difference
between an n-channel transistor and an NPN, same for p-channel PNP
transistors?

I don't have a counter in my library so I built a 4-bit ripple
counter out of D flops and decoded "10".
See how it works by changing the period and width of the pulses
coming out of V3.

Any suggestions for US based suppliers? Other than RadioShack?

Can anyone help me in designing a circuit for a musical fountain???

I'm trying to use a 555 timer to produce a PWM waveform however can't find
any reference as to how the value of the resistor* can be used to calcuate
the duty cycle. Is there a formula that says something like when you use
Xohms it gives 2X% duty cycle?

Im still working on ATmega16 which has buil-in A/D -converter. It
seems that the converter is a drain for 10mA current ( 0 - 5 V ).
Devise that feeds the analog voltage gives only 5mA ( 0 - 10 V ).  So
at the moment when I connect the lines, voltage drops heavily from

Hi. I am a new user. I need video lectures on electronics. any one
know sites providing free video lectures apart from MIT? Please reply.