1/ Capacitors and resistors have parasitic inductance, about 0.4nH for s
urface mount and 4nH for a leaded component.

2/ If you don"t want a high bandwidth transistor to oscillate place loss
y components in at least 2 of the 3 leads. Ferrite beads work well.

3/ When taking DC measurements in a circuit and they don"t make sense, s
uspect that something is oscillating.

4/ Opamps will often oscillate when driving capacitive loads.

5/ The base-emitter voltage Vbe of a small signal transistor is about 0.
65v and drops about 2mV/deg C. Vbe goes down with increasing temp.

6/ Multiply 0.13nV by the square root of the ohmic value of a resistor t
o find the noise in a 1Hz bandwidth. Then multiply by the square root of
 the BW in Hz gives the total noise voltage.

7/ Johnson noise current goes down with a increase in resistance.

8/ The impedance looking into the emitter of a transistor at room temp i
s 26Ohm/Ie in mA

9/ All amplifiers are differential in that they are referenced to ground
 somewhere.

10/ Typical metal film resistor has a temp coef of about 100 ppm/deg C

11/ The input noise voltage of a quiet op amp is 1nv/sqrt(Hz) but there
are plenty available with 20nV/sqrt(Hz). Op amps with bipolar front-ends
 have lower voltage noise and higher current noise than those with FET f
ront-ends

12/ Using an LC circuit as a power supply filter can actually multiply t
he power supply noise at the filter"s resonant frequency. Use inductor w
ith low Q to overcome this.
6/ Multiply 0.13nV by the square root of the ohmic value of a resistor t
o find the noise in a 1Hz bandwidth. Then multiply by the square root of
 the BW in Hz gives the total noise voltage.

7/ Johnson noise current goes down with a increase in resistance.

8/ The impedance looking into the emitter of a transistor at room temp i
s 26Ohm/Ie in mA

9/ All amplifiers are differential in that they are referenced to ground
 somewhere.

10/ Typical metal film resistor has a temp coef of about 100 ppm/deg C

11/ The input noise voltage of a quiet op amp is 1nv/sqrt(Hz) but there
are plenty available with 20nV/sqrt(Hz). Op amps with bipolar front-ends
 have lower voltage noise and higher current noise than those with FET f
ront-ends

12/ Using an LC circuit as a power supply filter can actually multiply t
he power supply noise at the filter"s resonant frequency. Use inductor w
ith low Q to overcome this.

13/ Use comparators for comparing and op amps for amplifying and don"t e
ven think of mixing the two.

14/ Ceramic caps with any other dielectric other than NPO should only be
 used for bypass applications.

15/ An N-channel enhancement-mode FET needs +ve voltage on the gate-sour
ce to conduct form drain-source.

16/ Small signal JFETS work very well as low-leakage diodes by connectin
g drain & source together in log current-to-voltage converters and low l
eakage input protection. Small signal bipolars with b-c tied together wi
ll also make nice low-leakage diodes.

17/ With low pass filter use Bessel for least amount of overshoot in the
 time domain, and Cauer (or elliptic) for fastest rolloff in the freq do
main.

18/ dB is always 10 times the log of the ratio of 2 powers.

19/ At low frequencies, the current in the collector of a transistor is
in phase with the applied current at the base. At high frequencies the c
urrent at the collector lags by 90deg. You must appreciate this simple f
act to understand high frequency oscillators.

20/ The most common glass-epoxy PCB material (FR4) has a dielectric cons
tant of about 4.3 To make a trace with a characteristic impedance of 100
 Ohm, use a trace thickness of about 0.4 times the thickness of the boar
d with a ground plane on the opposite side. For a 50Ohm trace make it 2
times the thickness.

21/ If you need a programmable dynamic current source, find out about op
erational transconductance amps. Most of the problem is figuring out whe
n you need a programmable dynamic current source.

22/ A CMOS output with an emitter follower can drive a 5V relay nicely a
s the relays normally have a must-make spec of 3.5V. This saves power an
d require no flyback components.

23/ Typical thermocouple potential is 30uV/degC. Route signals different
ially, along the same path, avoid temp gradients. DPDT latching relays w
on"t heat up when multiplexing these signals.

24/ You SHOULD be bothered by a design that looks messy, cluttered or in
direct. This uncomfortable feeling is one of the few indications that th
ere"s a better way.

25/ Avoid drawing any current from the wiper of a potentiometer. The res
istance of the wiper contact will cause problems (local heating, noise o
ffsets etc.)

26/ Most digital phase detectors have a deadband where the analog output
 does not change over the small range where the 2 inputs are coincident.
 This often-ignored fact has helped to create some very noisy PLL"s (Use
 a high val bleeding resistor to always ensure current flow in the deadb
and)

27/ The phase noise of a phase-locked VCO will be at least 6dB worse tha
n the phase noise of the divided reference for each octave between the c
omparison frequency and the VCO output frequency. Avoid low-comparison f
requencies.

28/ You can almost always determine the leads of a bipolar transistor wi
th an eat up when multiplexing these signals.

24/ You SHOULD be bothered by a design that looks messy, cluttered or in
direct. This uncomfortable feeling is one of the few indications that th
ere"s a better way.
"s front-end should be bootstrapped to the source (or emitter) so that t
he voltages on the part are not modulated by the input signal.

30/ If your design uses a $3 op amp, and you will be making a thousand o
f them, you have just spend $3000. Are you smart enough to figure out ho
w to use a $.30 op amp instead?

31/ The Q of an LC tank circuit is dominated by the losses in the induct
or in terms of series R. Q=omega.L/R

32/ Leakage current doubles for every 10degC increase in temp.

33/ When inputs to most JFET op amps exceed the common-mode range for th
e part, the output may reverse polarity. This artifact will haunt the de
signers of these parts for the rest of their lives, as it should!

34/ Understand the difference between "make-before-break" and "break-bef
ore-make" when you specify switches.

35/ 3 Terminal voltage regulators in the TO-220 packages are wonderful p
arts. They are cheap, rugged, thermally protected and very versatile. Us
e them virtually any place where you need a protected power transistor.
They also make nice AM power-modulators.

36/ Use step recovery diode where you need fast edges under 100pS (hot-c
arrier is even faster)

37/ The old 723 regulator is still one of the lowest noise regulators ar
ound! (2.5uVrms 100Hz-10k)

38/ You can make a very simple oscillator with one diac, cap and a resis
tor.

39/ NPN transistors are normally superior to their PNP counterpart in pe
rformance.

40/ Typical spec in some databooks should read "Seen it once". Always wo
rk with the worst spec of the part when doing a design.

41/ Don"t just copy circuits from application notes without understandin
g completely how it operates, and the reason for the choice of values.

arts. They are cheap, rugged, thermally protected and very versatile. Us
e them virtually any place where you need a protected power transistor.
They also make nice AM power-modulators.

36/ Use step recovery diode where you need fast edges under 100pS (hot-c
arrier is even faster)

37/ The old 723 regulator is still one of the lowest noise regulators ar
ound! (2.5uVrms 100Hz-10k)

38/ You can make a very simple oscillator with one diac, cap and a resis
tor.

39/ NPN transistors are normally superior to their PNP counterpart in pe
rformance.

40/ Typical spec in some databooks should read "Seen it once". Always wo
rk with the worst spec of the part when doing a design.

41/ Don"t just copy circuits from application notes without understandin
g completely how it operates, and the reason for the choice of values.

42/ Dealing with crystals, make sure you understand the difference betwe
en series and parallel resonant. In a circuit, crystal frequency can gen
erally be slightly lowered by placing a inductor in series and increased
 by a capacitor in series.

43/ Power MOSFETS on-resistance will have a -ve temp coef and not +ve at
 low current levels. This is important to remember when paralleling devi
ces.

44/ Lowest noise figure of a RF transistor is not normally where the inp
ut is perfectly matched.

45/ Many un-stable RF devices can be made stable by loading the input or
 the output by a simple resistor, either in series or parallel.

46/ You trade gain for bandwidth.

47/ Push-pull power invertors using bipolars are risky and can saturate
the core because of hysteresis stepping (use power fets)

48/ The Al value of a core will increase up to 50% or more under current
 transients.

49/ Be aware of leakage inductance when switching. V=L(dI/dt)

50/ The harder you turn-on a power transistor, the longer it will take t
o turn off.( the part where you burn the joules in the device)

51/ Always remember the Miller guy.

52/ In fault-finding a circuit, don"t overlook the obvious. (is there po
wer?)

53/ What is a ground loop, and how to avoid it.

54/ 120 is a better number than 240 when using LM3XX type adjustable reg
ulators.

55/ The lower comparator in the old 555 may have quite a long storage ti
me.

56/ ZERO-ESR caps may do more harm than good.

57/ A correctly configured audio power amplifier will give more distorti
on in Class-AB, not less, because of the abrupt gain changes inherent in
 switching from A to B every cycle.

58/ Be a STAR when it comes to ground matters.

59/ Know when you need to use a Zobel network.

60/ Use current mirrors and mirror your current.

61/ Heatsink eff decreases with height above sealevel.

62/ A matt-black heatsink is much better than a shiny one.

63/ Ignoring secondary breakdown can be costly.

64/ Understand fuses and fuse ratings, fast and slow. Do you know when t
o use a semiconductor-fuse?

65/ Charge balancing resistors are a must when stacking serie-parallel h
igh voltage capacitor banks.

66/ You must understand DC-restoration otherwise you will have a hard ti
me designing Z-modulation in CRT circuits.

67/ Display 6 vert div low freq on a scope, increase the freq (make sure
 the source is constant amplitude) until display drops to 4.2 div. That
is the true 3dB BW of the scope. (scope-source impedance should be match
ed)

68/ Doing a measurement with your DMM in the ACV position on your DC cir
cuit will give a quick indication of any excess ripple on the supply whe
n you don"t have a scope at hand.

69/ Dly timebase on a scope is very useful once you figured out when, wh
y and how to use it.

70/ Know what to expect before you measure, otherwise any measurement is
 meaningless.

71/ Op amps. Output will swing in the direction that will force the inv-
input level to try come closer to the non-inv input level.

72/ Understand virtual ground, slew-rate, CMRR and PSRR. (CMRR decrease
with increase in freq)

73/ Making measurements near a spec-analalyzer"s noise floor will give 3
dB errors.

74/ Understand the phase-noise limitations of the analyzer when making s
uch measurements on oscillators.

75/ In a LC oscillator add some C with -ve temp coef to cancel the +ve t
emp coef of the L for min drift with temp.

76/ Less drift will result from making C with a few parallel caps, to re
duce the heating effect of the oscillating current when spread out over
a larger plate area.

77/ You will get more tuning range with the same LC combination in a Cla
pp than in a Colpitts circuit.

78/ High-Q tuned LC filters will have more insertion loss.

79/ Williams"s Rule (Guru at Linear Tech) for precision op amp circuits:
 " Always invert (except when you can"t)"

80/ Cuk is not a kind of locomotive.

81/ If you don"t know how to make a design better, find out what makes i
t worse.

82/ Sometimes you know just enough to be dangerous.

83/ Impedance will reflect back as the square of the turns ratio.

84/ If you could design a component with the characteristics of a finger
 it could cure many design problems and you will be rich.

85/ Get nervous when the customer you are trying to help doesn"t even ha
ve a scope.

86/ Specs quoted by reps always exceed those by Engineering.

87/ A bad (Engineer) workman always blames his tools.

88/ Don"t believe everything that a SPICE program spits out.

89/ It is easy to get the color code of a 1kOhm and 12Ohm resistor mixed
 up when you are in a hurry.

90/ I bet one could write a thesis about the ability of probes to get ta
ngled-up on a bench.

91/ DMM can upset sensitive circuits from noise generated inside it.

92/ When probing directly on a crystal of a uP, use 10kOhm or so resisto
r in series with the probe tip to prevent loading from stopping the osc.

93/ It is easier to see what is happening on the ports using a scope whe
n you trigger one chan against the cpu clock.

94/ National once made a bad op amp many years ago that some Engineers r
eferred to it as "Jelly Beans"

95/ The moment you can start to notice distortion on an oscilloscope it
is already way past being acceptable.

96/ Be big enough to say "I don"t know", people will respect you more.

97/ The best designer is often working in the marketing department.