Digital Tutorials
These were tutors which i made around
1999, these are interactive and
started with basic JavaScript and CSS.
You can operate the controls and see
the Truth Table and Results in LED
Displays. Controls include DIP
Switches and Push Buttons.
Here is a good book to start learning
- CMOS
Mixed-Signal Circuit Design - R
Jacob Baker
See a Tutor on Digital Numbers - Binary
and Hex Numbers see a Basic
Digital Product here, made of Cmos
chips - Simple
Digital Event Counter. These
technologies have been replaced by the
uC systems.
Both CMOS or uC counting systems are
susceptible to spikes, EMI and power
jerks. A Solenoid valve operating
nearby can reset a CMOS counter or
Hang up a uC based Counter. The uC
based system needs a watchdog and good
EMI safegaurds. The CMOS systems just
needs a good supply and isolated
input/outputs.
See here a 555
watchdog for uC and uP systems.
Digital circuits have to have a nice
0.1uF cap at the head of each IC.
Decoupling. I/O isolation, no ground
loops. Excellent EMI RFI immunity.
Power Supply with Capacitor Bank or
battery to combat Blackouts and
Brownouts. See my answers to a problem
here- RS
Latch Erroneously setting by Itself.
The CD40xx CMOS family can work at
even 3V-9V-12V DC and consume low
power. The speed is not as fast as
74xx TTL family. It is good for
simple portable battery powered
circuits. The 74HCTxx series is good
for low power and high speed but
will work at 5V. When you have
problems interfacing CMOS and TTL
use 74HCTxx family.
Amps-n-Volts Notes Corrected
Improved
Amps-n-Volts eMag Near 2001 i
started sharing my learning and
experience in Electronics
Engineering on Blogs and
Newsletters. One of the Successful
eMag and electronic email magazine
ran for five years. It has listed my
jots and notes in pages, designs and
the brain accumulated for more than
two decades.

Learning the way
Electronic Things Behave
- Before you open a PC remove
power, telephone modem and LAN
cables else finger and screwdriver
in wrong place can zap chips.
- The products that survive the
infant mortality time of say first
six months will last quite long.
- NTSC is like 320 x 240 pixels,
which is TV, which is lower than
your computer's 800 x 600.
- When a microwave oven is turned
on, a big spike is caused in the
power line due to heavy inrush
current on start up, Even pumps
and motors cause such short time
surges. This causes tripping of
electrical protection circuits.
- When a tree branch falls on the
high voltage overhead electrical
lines, they spark violently and
supply trips.
- Big or tall trucks go in small
roads they may snap all low level
cable or telephone wires on their
way.
- Do you need to turn on many
equipments-machines all at once?
do it one after an other
sequentially or use a timer for
delays. This is because at peak
power demand time, turning on all
can cause your fuse to blow or
worse.
- A battery that can be charged is
best charged in CC constant
current and CV constant voltage
modes, that means both current and
voltage have to be limited. When a
battery is deep discharged many
times it will age fast, and an
empty battery will take huge
currents so limit current.
overcharging a battery will
killit. After a voltage level is
reached it should only trickle
charge in mA and a battery has to
be cut off on overload or before
deep discharge
- The Lead acid battery breathes a
lot, so keep them in a well
ventilated open space but rain
proof. Use sealed maintenance free
battery when possible, these are
safer.
- Teflon tape can be used to make
leak proof pneumatic or hydraulic
connections if junctions are
leaking.
- The current thru a 3mm or 5mm
LED (light emitting diode) should
not exceed 20mA, 15mA is quite
good.
- In a circuit swap all PNP
and NPN
, reverse all diodes and el-caps,
reverse the supplies and input
polarities, most of the circuit
may still work like they did
before.
- A sharp bend in a PCB track is a
huge inductance (say 1nH ) when it
comes to RF. it may radiate or
reflect, it may even act like an
antenna and pick up RF from the
SMPS, Motor or Cellphones nearby.
- Persistence of vison around 16
frames a second (60mS) hence very
fast events not seen .
Some of these points may be repeated
and some not relevant in the present
technical engineering scenario. As
issues may have been set right, years
back.
Amps-n-Volts Archive
Instrumentation Notes
Design Notes
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