Electronic Circuits - Schematics & Tutorials Links CIRCUIT
COLLECTION 100
GUESTBOOK
HOME
We have put here a collection of circuits, many audio related. While many published
circuits are not the finest available solutions today, they represent great ideas. If
you would like your circuit or link collection be published here, send e-mail with related
material, we will format it and add to our collection. Thank
you! Publish
my circuit
Electronics Tutorials - Extensive resources for circuit
design http://www.williamson-labs.com
Technick.net - Tons of hardware info and more http://www.technick.net
Electronics Tutorials - Extensive resources for circuit design,
biased toward RF, by Ian C. Purdie, VK2TIP http://www.electronics-tutorials.com
The Self Site - Audio circuitry, extensive notes, diagrams by Douglas
Self http://www.dself.demon.co.uk
Circuitry Links Collection - by Tome Loredo, within Electronics
resources http://astrosun.tn.cornell.edu/staff/loredo/ee.html#sim
Audio Circuits To Build - By ePanorama.net http://www.epanorama.net/audiocircuits.html
Circuit Collection - By CommLinx Solutions http://www.commlinx.com.au/schematics.htm
The Audio Pages - Design Information, Projects by Elliott Sound Products
http://sound.westhost.com
The Class-A Amplifier Site - By Geoff Moss http://www.gmweb.btinternet.co.uk
Bama's Bunker - Audio Circuitry Links http://www.eeph.com/~james/schematics_micpreampsmixers.html
Electronic Circuits - Electronics Zone http://www.electronic-circuits-diagrams.com/audio_circuits.shtml
Carl's Electronics, Inc. - 200 Electronic Kits http://www.electronickits.com
Electronic Projects for R/C - by John Nooyen http://www.uoguelph.ca/~antoon/gadgets/gadgets.htm
Cyber Circuit - by PTM http://www.uslink.net/%7Ecybercir/cirplist.htm
Poptronics Magazine & The Ties Magazine Circuits - for simulation
with free demo of Electronics Workbench http://www.electronicsworkbench.com
Bowden's Hobby Circuits - Over 100 circuit diagrams, links to related sites, commercial kits and projects,
newsgroups and educational areas. http://ourworld.compuserve.com/homepages/Bill_Bowden/homepage.htm#menu
555 Timer by Ron Harrison - Most extensive tutorial we found on the
web about 555 timer http://pace.inesc.pt/~eleII/555tutorial.htm
Timer by Ron Harrison - Most extensive tutorial we found on the
web about 555 timer http://pace.inesc.pt/~eleII/555tutorial.htm
CIRCUIT
COLLECTIONS 100
200
Circuit 1 Negative resistor cancels op-amp load.
High accuracy op-amp have a problem driving low impedance loads. One solution is to "cancel" the load. If your resistive load is R and you connect it in parallel with a negative resistor of -R, the resistance of the parallel combination is infinite. Circuit presents a practical application of the concept.
By EDN Magazine, May 24, 2001, Design Ideas, page 108. http://www.ednmag.com jpg 100kB
Circuit 2 Dual
microphones separates voice from noise
Two microphones placed equidistant from user's mouth on the user's chest produce
in-phase signals to this noise canceling circuit's multiplier, separating the
user's voice and out-of-phase signals from background noise. Uses AD638 as
bipolar 4-quadrant multiplier.
By EDN Magazine, Design Ideas Annual, page 94. http://www.ednmag.com jpg 76kB
Circuit 3 Ultrasound
transducers form proximity detector
Combining micropower op amps with a pair of matched piezoceramic transducers
(one optimized for 40 kHz transmission and the other for 40 kHz reception)
yields an ultrasonic proximity detector. The detector employs the radar
principle - nearby people or objects reflect the transmitter's steady tone back
to the receiver. The transmitter is based on ICM7555 timer, while the receiver
employs high bandwidth MAX403 op amp.
By EDN Magazine, April 9, 1992, Design Ideas, page 145. http://www.ednmag.com jpg
91kB
Circuit 4 Bipolar
circuit stabilizes power
This circuit solves constant power circuit and works with single supply. It is
based on Gilbert's multiplication cell, the circuit is another useful
application of translinear circuits. 4 NPN and 3 PNP transistors are used
in such configuration that makes the power dissipated in the resistive load
constant and independent on load variation.
By Circuit & Devices, continuation of Nov 1991 circuit. V.A. Piskarev -
Severnaya Zarya - St. Petersburg, Russia and L.M. Filanovsky - University of
Alberta - Edmonton, Canada
Bipolar_circuit_stabilizes_power_jpg_52kB
Circuit 5 Paralleled
amplifiers drive quietly
By paralleling amplifiers, you can increase load drive while keeping output
impedance low and reducing noise voltage. This circuit uses inverting and
non-inverting configuration with 4 op amps. Calculations demonstrate noise
reduction.
By EDN Magazine, April 23, 1992, Design Ideas, page 171, by Moshe Gerstenhaber
& Mark Murphy from Analog Devices Sem.
Paralleled_amplifiers_drive_loads_quietly_jpg_139kB
Circuit 6 110 dB Beeper
Circuit
Most piezoelectric beeping devices with internal drivers lack sound intensity,
only producing 80 dB SPL with 9 V supply. This circuit will produce 110 dB SPL
from 9 V battery, using Panasonic EFB-BD32B21 piezo alarm and 74C14 chip.
By Electronic Design, AUG 5, 1993, page 81, by David A. Johnson
110_dB_beeper_circuit_jpg_102kB
Circuit 7 Cascode
circuit works from 1 V supply
Most piezoelectric beeping devices with internal drivers lack sound intensity,
only producing 80 dB SPL with 9 V supply. This circuit will produce 110 dB SPL
from 9 V battery, using Panasonic EFB-BD32B21 piezo alarm and 74C14 chip.
By Electronic Design, May 21, 1992, by Ian M Wiles, IPR Technology, Basingstoke,
Hants, UK
Cascode_circuit_works_from_1Vsupply_113kB
Circuit 8 Diode
simulator reduces forward drop to 0.04V
To gain higher power efficiency, a lower then 0.7V diode drop is sometimes
desirable. This simple circuit exhibits a voltage drop of 0.04V with 1A of
forward current. Based on low cost op amp (LM393) and MISFIT transistor
(IRFZ40), it requires two supplies and provides two terminals: Diode Cathode +
Diode Anode.
By Electronic Design, May July 20, 1992, by Isaac Eng, ESTCO Battery
Engineering, Ottawa, Ontario
Diode_simulator_reduces_forward_voltage_jpg_75kB
Circuit 9 Circuit
vocalizes telephone number
To gain higher power efficiency, a lower then 0.7V diode drop is sometimes
desirable. This simple circuit exhibits a voltage drop of 0.04V with 1A of
forward current. Based on low cost op amp (LM393) and MOSFET transistor
(IRFZ40), it requires two supplies and provides two terminals: Diode Cathode +
Diode Anode.
By Electronic Design, Feb 3, 1994, by Malcolm Watts, Wellington Polytechnic,
Wellington, New Zeland
Circuit_vocalizes_telephone_number_jpg_89kB
Circuit 10 MOSFET
replaces switch
By using a cheap, readily available MOSFET, you can use a single-pole switch to
turn a bipolar power supply on and off without consuming extra power.
MOSFET_replaces_switch_jpg_51kB
Circuit 11 Buffer tree
multiplies dc supply voltages
The "buffer tree" can multiply a dc supply voltage by any whole
number. The circuit successively adds the supply voltage to itself using a
cascadable circuit element. The circuit element comprises two capacitors and
paralleled HEX inverters configured as a noninverting buffer. The circuit relies
on the bidirectional properties of MOSFETs. By EDN Magazine, May 7, 1992,
Design Ideas, page 201.
Buffer_tree_multiplies_dc_supply_voltages_jpg_67kB
Circuit 12 CMOS
switches develop negative voltage
The simple negative-voltage converter works over an input range of 3 to 9V with
an internal resistance ranging from 2000 to 400 Ohm, depending on input voltage
and output loading. By EDN Magazine, July 22, 1993, Design Ideas, page 46.
CMOS_switches_develop_negative_voltage_jpg_69kB
Circuit 13 Fast buffer
splits power supply
The high-speed buffer can sink or source enough current to derive a new, stable
output ground, splitting the input supply. The EL2008 used has a 1 Ohm output
impedance. The buffer allows the circuit to handle unbalanced load currents that
a simple resistive divider could not. By EDN Magazine, July 22, 1993,
Design Ideas, page 48.
Fast_buffer_splits_power_supply_jpg_48kB
Circuit 14 Driver
isolates itself from transducers
Ultrasonic transducers are part of a variety of circuits such as motion
detectors and range finders. One design practice is to operate the transducers
as matched pairs of one transmitter and one receiver. Presented circuit is an
alternative design practice in which a single transducer acts as a transceiver.
By EDN Magazine, July 22, 1993, Design Ideas, page 58
Driver_isolates_itself_from_transducers_jpg_166kB
Circuit 15 Low cost
active load draws constant battery power
Unlike nickel-metal-hibride and lithium-ion rechargeable batteries, the
discharge voltage of alkaline batteries is not constant and tends to vary from
1.5 to 1.8V per cell. Alkaline-battery manufacturers specify the discharge life
of their batteries under constant power loads. Thus the circuit draws a constant
power from the battery pack. By EDN, April 13, 2000, Design Ideas, page 210.
Low_cost_active_load_draws_constant_battery_power_jpg_97kB
Circuit 16 Single stage
gives logarithmic gain steps
By placing a variable component in the positive feedback loop of an op amp, you
can vary the gain of the stage logarithmically with respect to a linear
resistance or conductance. Such a stage could prove useful, for example, in an
audio circuit where you need a linear "dB" response. By EDN Magazine,
March 3, 1994, Design Ideas, page 98.
Single_stage_gives_logarithmic_gain_steps_jpg_115kB
Circuit 17 Measuring
differential delay with sine squared pulses
"Ripple in a sum signal indicates differential delay". A technique for
measuring differential delays among red, green and blue signals transmitted on
different parallel channels exploits the sine-squared pulses that are parts of
the standard test signals transmitted during the vertical blanking interval of
the frame period. By NASA Tech Briefs, Feb 1994.
Measuring_differential_delay_with_sine_squared_pulses_jpg_126kB
Circuit 18 Inverters
form three phase VCO
You sometimes need an inexpensive VCO that can produce evenly spaced three-phase
outputs over a wide frequency range. Presented circuit produces relatively
squarish waveforms and consists of only the 3 inverters. By EDN Magazine, Aug 2,
2001, Design Ideas, page 102
Inverters_form_three_phase_VCO_jpg_166kB
Circuit 19 Get negative
rail using CMOS gates
By implementing this inexpensive circuit built with CMOS gates, a negative rail
can be obtained from a positive supply. The circuit's input range is 1.2 to 7.0
V, and no load loss is only 1 mV. The negative rail can be generated from one
1.5 V cell. By Electronic Design, March 28, 1991, Idea
for design, page 117.
Get_negative_rail_using_CMOS_gates_jpg_79kB
Circuit 20 Circuit
amplifies without amplifiers
The circuit amplifies a dc signal using switches and charge-storage capacitors.
It has a fixed gain of 8 and averages the input signal over eight timing
periods.
By EDN Magazine, April 23, 1992, Design Ideas, page 184.
Circuit_amplifies_without_amplifiers_jpg_65kB
Circuit 21 Build
efficient DC Lamp dimmer
A linear voltage regulator scheme is often employed to control dc lamp
brightness. This approach is usually worse than 50% efficient. An alternative is
the pulse width modulated approach, which can yield efficiency of 96% or better.
Prsented circuit forms a narrow pulse generator with a frequency of about 200
Hz, and a pulse width of approximately 0.1 ms. With lamp load of up to 24 W,
there is no need for a heat sink.
Build_efficient_DC_Lamp_dimmer_jpg_77kB
Circuit 22 Build ultra
low dropout regulator
Switching regulator post regulators, battery powered apparatuses, and other
applications often require low dropout linear regulators. This simple circuit
offers a lower dropout voltage than available monolithic regulators, with 50mV
at 1A and 450mV at 5A. The 3 pin LT1123 regulator servo controls base of PNP,
power transistor MJE1123.
Build_ultra_low_dropout_regulator_jpg_136kB
Circuit 23 Circuit
eliminates PC echoes
Long distance telephone services available via the Internet often require the PC
user to wear headphones of a headset to prevent echo caused by the microphone's
picking up the loudspeaker outputs. Presented circuit eliminates echo while
using the existing PC microphone and speakers for a comfortable conversation.
Circuit_eliminates_PC_echoes_jpg_86kB
Circuit 24 Ultrasonic
range finder uses few components
An ultrasonic,or sonar, range finder is a common sensor in robotic systems and
industrial environments. A novel sensor design uses a uC, a few peripheral
components, and a pair of ultrasonic transducers. Usable range is about 4"
to 16', with accuracy of +/-2".
Ultrasonic_range_finder_uses_few_components_jpg_205kB
Circuit 25 5V to 1.8V
converter works without magnetics
To derive 1.8V from 5V, you might use a switching mode regulator, very efficient
but expensive, linear regulator, low cost but not efficient - or a CMOS charge -
pump voltage converter. Presented converter has better than 70% efficiency,
sources as much as 100 mA, costs less and takes less space than switching mode
regulator.
5V_to_1.8_converter_works_without_magnetics_jpg_68kB
Circuit 26 Sensor
adapts to changing light levels
Presented circuit dynamically adjusts itself, changing long term conditions,
while monitoring the transparency of a medium. The circuit has two servo loops:
One having a long time constant that maintains a steady level of light
excitation through the monitored medium, and another having a short time
constant that sets the threshold for detecting sudden changes in the medium's
transparency.
Sensor_adapts_to_changing_light_levels_jpg_96kB
Circuit 27 Special Low
Pass filter limits slope
Adding several components to a simple first order, low pass filter, helps to
create a different yet handy filter. This simple circuit combines a low pass
filter with a bidirectional diode clipping network. The result is a filter that
will limit the maximum slope (not frequency) it passes.
Special_low_pass_filter_limits_slope_jpg_165kB
Circuit 28 Simple sine
wave generator has no filters
Generating sine waves with controlled frequencies over a wide range is difficult
when using RC or LC sinusoidal oscillators. However, this performance can be
simply created using a wideband digital squarewave generator, a counter, and a
weighted summing network. Using such principle, a sinusoidal signal with a
100,000,000 to 1 frequency range from about 1 MHz to under 0.01 Hz can be
obtained without a need for any low pass or high pass filters. The circuit uses
4040, 4030 and OP77 chips.
Simple_sine_wave_generator_has_no_filters_jpg_94kB
Circuit 29 Constant power
load needs only a few components
Switching dc-dc converters are often used in portable or battery backed projects
because of their broad input voltage range and high efficiency. These converters
present a constant power load to the battery - their input current increases as
the battery voltage decreases. Presented circuit simulates real life battery
discharge scenario, allowing accurate testing of battery life.
Constant_power_load_needs_only_a_few_components_jpg_224kB
Circuit 30 Comparator
has independent trip voltages
For an inverting amplifier with histeresis, 3 resistors determine the crossover
voltages. Unfortunately, using 3 resistors to set the upper and the lower trip
voltages creates a dependence between the two trip voltages. It's impossible to
set one voltage without affecting the other. Open - collector circuit solves
this problem.
Comparator_has_independent_trip_voltages_jpg_77kB
Circuit 31 Switched
capacitor regulator provides gain
Presented circuit with switched capacitors dramatically increases voltage
inverter efficiency, when input voltage is more than twice the desired output
voltage, for example using 12 V to obtain 3.3 V. A typical switched capacitor
voltage inverter to generate negative voltage from positive voltage is modified
to step down regulator with current gain of 2. By EDN Magazine, March 13,
1998, Design Ideas, page 80.
Switched_capacitor_regulator_provides_gain_jpg_128kB
Circuit 32 Capacitor
amplifier reduces ripple without dc loss
Filter capacitors reduce ripple in power supply circuits or provide pulse energy
at a constant dc voltage. In both applications, there is fundamental conflict.
The circuit needs constant voltage, but energy storage and delivery capability
is a function of capacitance and of voltage change squared. To achieve a low
ripple output, a large, costly capacitance is needed. The emitter follower
circuit boosts the output capacitor effectiveness in reducing ripple, but
induces large dc loss. Presented circuits show alternative solutions. By
EDN Magazine, June 6, 1996, Design Feature, page 138.
Capacitor_amplifier_reduces_ripple_without_dc_loss_jpg_344kB
Circuit 33 Active
transformer for audio input
Line receivers with high common mode input impedances clearly produce higher
CMRR in real world balanced interfaces. Presented circuit yields high ac common
mode impedances yet leaves a low resistance path to ground for dc at the
input. By EDN Magazine, June 4, 1998, Design Feature, page 144.
Active_transformer_for_audio_input_jpg_117kB
Circuit 34 1.5V Battery
powered fan switches ON and OFF by hand
This circuit represents a very simple and inexpensive alternative to an
electrical switch used to turn ON and OFF the battery operated dc motor
typically employed in in handheld fans. It eliminates the mechanical components
that could suffer from humidity, condensation or bad contacts. You can switch ON
the motor by simply giving it a small rotation with your hand. This movement
produces a voltage drop between the motor terminals, which is sufficient to
activate switching transistor. By Electronic Design Magazine,
www.elecdesign.com, Massimo Gottardi, Trento, Italy.
1.5V_battery_powered_fan_switches_ON_and_OFF_by_hand_jpg_94kB
Circuit 35 Short-circuit
finder uses few parts
The simple tester detects short circuits on assembled pc boards and also rings
out cables and harnesses. It has a narrow zone of threshold uncertainty and very
low "insertion" voltage and current. It is not confused by capacitors.
Based on LM10, it works with 1.1 to 40 V supply. By EDN Magazine, NOV 5,
1998, Design Ideas, page 130.
Short_circuit_finder_uses_few_parts_jpg_67kB
Circuit 36 Low noise
voltage source
Measuring semiconductor performance often requires a low noise voltage source.
Commercially available power supplies use electronic voltage references and may
produce too much low frequency noise to get accurate measurements. Presented
simply circuit generates noise two to three magnitude lower compared to
commercial power supplies. By Test & Measurement World, AUG 1998, page
15, www.tmworld.com
Low_noise_voltage_source_jpg_244kB
Circuit 37 Low
frequency oscillator draws only 500nA
The low frequency square wave oscillator is based on CD4007UB and a few passive
components. It draws only 0.5 uA from a 6 Vdc supply. It produces about 2 Hz,
with available high frequency near 300 Hz. By EDN Magazine, SEP2, 1993, Design
Ideas, page 118.
Low_frequency_oscillator_draws_only_500nA_jpg_74kB
Circuit 38 Capacitive sensor
"likes" parasitics
Stray capacitance is a common problem with capacitive sensors. The capacitance
changes within the measurement range are normally much smaller than the strays,
the result is a loss of sensitivity. Various methods are available to increase
relative sensitivity. Instead of, presented circuit uses the stray and turns its
drawbacks to your advantage. By EDN Magazine, SEP 24, 1998, Design Ideas,
page 180.
Capacitive_sensor_likes_parasitics_jpg_177kB
Circuit 39
Potentiometer sets bandwidth, no gain
The circuit allows you to adjust the pulse response (bandwidth) independently of
the gain - with a potentiometer in series with the inverting input of a current
feedback op amp. By EDN Magazine, May 11, 2000, Design Ideas, page 177.
Potentiometer_sets_bandwidth_no_gain_jpg_190kB
Circuit 40 Cable finder
seeks out wall conduits
The circuit uses an antenna in the wall and a receiver to locate a cable
conduit, useful for brick walls with iron elements. When you debug home
electrical wiring, a tool that determines the location of cable conduits comes
in handy. Some short range finders are good for brick walls, but not for walls
consisting of iron elements. Presented circuit uses an antenna in the wall
conduit and a receiver to locate a cable conduit, with 74HC132 and a few easily
available parts. The combination can accurately locate the antenna
placement. By EDN Magazine, MAY 11, 2000, Design Ideas, page 178.
Cable_finder_seeks_out_wall_conduits_jpg_110kB
Circuit 41 Circuit
forms industrial-grade digital potentiometer
This solid state potentiometer simulates a mechanical potentiometer and fits in
the same space. It produces a signal of 0 to 10 V, with a few parts involved.
The key to the circuit is the low power, digital potentiometer 100 kOhm IC,
configured as a voltage divider, providing an output of 32 discrete voltage
steps. By EDN Magazine, SEP 20, 2001, Design Ideas, page 104.
Circuit_forms_industrial-grade_digital_potentiometer_jpg_113kB
Circuit 42 Excel offers
painless LCD initialization
To display a font or a symbol on an LCD, you need to convert the desired
character into numerical data. Creating the data for an entire font set requires
specialized tools, even with these tools, the task can be daunting.
Alternatively, you can build a font calculator using an Excel spreaddsheet.
By EDN Magazine, SEP 20, 2001, Design Ideas, page 98
Excel_offers_painless_LCD_initialization_jpg_90kB
Circuit 43 Passive
filter cleans up power-line communications
A power line communications system needs input and output filters to eliminate
interference. Presented filter uses passive components because of the
requirement for low power consumption. By EDN Magazine, Sep 20, 2001,
Design Ideas, page 106.
Passive_Filter_cleans_up_power_line_com_1_jpg_70kB
Passive_Filter_cleans_up_power_line_com_2_jpg_45kB
Circuit 44
Microcontroller selects minimum/maximum value
Microcontroller based systems for measurement, sensor data processing, or
control, sometimes require you to determine a maximum or minimum data value. Two
approaches presented here use MC68HC705KJ1: Microcontroller stores data values
in memory before processing (a), or processes data on the fly (b). By EDN
Magazine, SEP 20, 2001, Design Ideas, page 100.
Microcontroller_selects_min_max_value_1_jpg_69kB
Microcontroller_selects_min_max_value_2_jpg_117kB
Circuit 45 Circuit
makes simple FSK modulator
Commercial FSK (frequency shift keying) modulators are bulky and need many
passive parts. Presented circuit uses a single inverter, NL27WZ14 gate, to
generate continuous FSK date from TTL level signals. When input state changes, a
continously running generator changes frequency by introducing an extra
capacitor to RC network. By EDN Magazine, Shyam Tiwari, Sensors technology Ltd,
Gwalior, India.
Circuit_makes_simple_FSK_modulator_jpg_72kB
Circuit 46 Circuit
detects first event
Presented circuit is a "first event"indicator, like a game show's
"who's first to answer" detector. It indicates which of the two
momentary switches closes first. The circuit can be cascaded to obtain more
channels. By EDN Magazine, May 3, 2001, Design Ideas, page 89.
Circuit_detects_first_event_jpg_97kB
Circuit 47 Passive
filters fill the bill at audio frequencies
Low-frequency filters, particularly at audio frequencies, usually take the form
of active filters. They have many advantages, but passive filters remain a
viable option when you quickly need low cost prototypes and test pieces. Passive
filters require no dc supply and no complex pc boards. By EDN Magazine, Feb
2001, Design Ideas, page 128.
Passive_filters_fill_the_bill_at_audio_frequencies_jpg_96kB
Circuit 48 Circuit
improvement on first event detection
This circuit requires less passive components, less expensive ICs and easy
scalability, compared to earlier published circuit (EDN, May 3, 2001, pg
89). This is the n-player first event detection circuit with several
improvements. By EDN, Aug 16, 2001, Design Ideas, page 106.
Circuit_improvement_on_first_event_detection_jpg_147kB
Circuit 49 Convert
periodic waveform to square waves
Converting periodic waveforms to square waves is an integral part of extracting
a clock signal from data, creating waveform generators and making timing-pulse
generators. Any square-wave conversion circuit is more valuable when the square
wave's duty cycle is variable and controllable. This comparator, integrator and
TTL gate based circuit has all these attributes. EDN Magazine, Aug 16, 2001,
Design Ideas, page 105.
Convert_periodic_waveform_to_square_waves_jpg_126kB
Circuit 50 Circuit
combines power supply and audio amplifier
The circuit presented help if you need to transfer dc power and audio over a
pair of copper wires. One application for such circuit is a low cost door
opening system with speech input. The circuit uses only one IC, the well known
LM317, a low cost power supply. Using the chip, you can modulate the adjustment
pin input with the audio signal from an electret condenser microphone. EDN
Magazine, Dec 20, 2001, Design Ideas, page 62.
50_Circuit_combines_power_supply_and_audio_amplifier_jpg_75kB
Circuit 51 Supply
derives 5 and 3.3V from USB port
Portable devices like digital cameras, MP3 players and PDAs can derive their
power from a USB port. This circuit produces 5V and 3.3V, while allowing the
port to maintain communications - and charges a lithium-ion battery at a
time. EDN Magazine, Dec 20, 2001, Design Ideas, page 62.
51_Supply_derives_5_and_3.3V_from_USB_port_jpg_112kB
Circuit 52 Transistor
tester fits into your pocket
This simply tester allows you to test the polarity and function of a transistor.
You connect the transistor, or device under test, between the collectors of an
unstable multivibrator. Thus, the Vce voltage of the device under test is
alternately positive and negative. EDN Magazine, Dec 20, 2001, Design
Ideas, page 60.
52_Transistor_tester_fits_into_your_pocket_jpg_87kB
Circuit 53 Analog
switch lowers relay power consumption
Unlike transistors, relays' switch contacts are electrically isolated from the
control input. However, the power dissipation in a relay coil may render the
device unattractive in battery powered applications. You can lower this
dissipation by adding an analog switch that allows the relay to operate at a
lower voltage. EDN Magazine, Dec 20, 2001, Design Ideas, page 57.
53_Supply_derives_5_and_3.3V_from_USB_port_jpg_101kB
Circuit 54 Analog -
input circuit serves any microcontroller
With two transistor arrays and three discrete components, you can configure an
analog front end for a microcontroller. Thus this simple ADC circuit is perfect
for getting analog signals into a purely digital microcontroller.
EDN Magazine, Dec 20, 2001, Design Ideas, page 58.
54_A_Supply_derives_5_and_3.3V_from_USB_port_jpg_106kB
54_B_Supply_derives_5_and_3.3V_from_USB_port_jpg_26kB
Circuit 55 Dual digital
POT creates accurate, temperature stable amp
The thermal performance of a simple gain circuit using a digital potentiometer
in typical configuration is typically 800 ppm/deg C. It can be easily raised to
1 ppm/deg C with presented solution. Electronic Design Magazine, Dec 17, 2001,
Ideas for design, page 59.
55_Dual_digital_pot_creates_accurate_temp_stable_amp_jpg_153kB
Circuit 56 Circuit
efficiently switches bipolar LED
Typical switching circuit for a bipolar, two color LED wastes power and does not
work with low supply voltage. Improved circuit employes a "flip-flop"
switch, the only losses come from the Vcesat and the base currents of the
transistors. EDN Magazine, Nov 22, 2001, Design Ideas, page 98.
56_Circuit_efficiently_switches_bipolar_LED_jpg_74kB
Circuit 57 Circuit
forms adjustable bipolar clamp
EDN Magazine, Nov 22, 2001, Design Ideas, page 100.
57_Circuit_forms_adjustable_bipolar_clamp_jpg_71kB
Circuit 58 Analog -
input circuit serves any microcontroller
Electronic Design Magazine, Dec 3, 2001, Ideas for design, page 83.
58_A_Simple_LED_flasher_yields_99%_power_reduction_jpg_119kB
58_B_Simple_LED_flasher_yields_99%_power_reduction_jpg_12kB
Circuit 59
Universal impedance generator handles biomedical applications
Electronic Design Magazine, Dec 3, 2001, Ideas for design, page 84.
59_A_Universal_impedance_generator_handles_biomedical_applications_jpg_128kB
59_B_Universal_impedance_generator_handles_biomedical_applications_jpg_23kB
Circuit 60 Single gate
VHF temperature transmitter runs on 3.6V
Electronic Design Magazine, Dec 3, 2001, Ideas for design, page 86.
60_Single_gate_VHF_temp_transmitter_runs_on_3.6V_jpg_88kB
Circuit 61 Build your
own bypass capacitor tester
EDN Magazine, Dec 6, 2001, Design Ideas, page 116.
61_Build_your_own_bypass_capacitor_tester_jpg_92kB
Circuit 62 Circuit
compensates optocoupler temperature coefficient
EDN Magazine, Nov 22, 2001, Design Ideas, page 93. 62_Circuit_compensates_optocoupler_temp_coefficient_jpg_110kB
Circuit 63 Improve FET
based control
EDN Magazine, Dec 6, 2001, Design Ideas, page 112.
63_Improve_FET_based_gain_control_jpg_98kB
Circuit 64 Noncascaded
arrangement optimizes bridged amplifiers
Electronic Design Magazine, Nov 19, 2001, Design Ideas, page 87.
64_Noncascaded_arrangement_optimizes_bridged_amplifiers_jpg_118kB
Circuit 65 Thermostat
for high altitude atmospheric sampler is fault tolerant
Electronic Design Magazine, Nov 19, 2001, Design Ideas, page 88.
65_A_Thermostat_for_high_altitude_atmospheric_sampler_is_fault_tolerant_jpg_140kB
65_B_Thermostat_for_high_altitude_atmospheric_sampler_is_fault_tolerant_jpg_72kB
Circuit 66 Manually
operated digital pot is revisited
Electronic Design Magazine, Nov 19, 2001, Design Ideas, page 90.
66_Manually_operated_digital_pot_is_revisited_jpg_83kB
Circuit 67 Circuit
converts pulse to voltage
Electronic Design Magazine, Oct 25, 2001, Design Ideas, page 92.
67_A_Circuit_converts_pulse_width_to_voltage_jpg_75kB
67_B_Circuit_converts_pulse_width_to_voltage_jpg_32kB
Circuit 68 Short dc
power line pulses afford remote control
EDN Magazine, Oct 25, 2001, Design Ideas, page 94.
68_A_Short_dc_power_line_pulses_afford_remote_control_jpg_101kB
68_B_Short_dc_power_line_pulses_afford_remote_control_jpg_81kB
Circuit 69 Circuit
forms efficient cosine calculator
EDN Magazine, Oct 25, 2001, Design Ideas, page 87.
69_A_Circuit_forms_efficient_cosine_calculator_jpg_81kB
69_B_Circuit_forms_efficient_cosine_calculator_jpg_34kB
Circuit 70 Reference
stabilizes exponential current
The use of matched transistors balances the first order temperature coefficient
but leaves temperature dependent gain term q/kT. Clasic antilog circuits use a
thermistor in the drive circuitry to correct this temperature dependency.
However, you can achieve an exact temperature correction by adding a second
reference transistor. With 3 op amps, 3 transistors and a few
passive components, presented circuit forms a temperature independent antilog -
ratio circuit. EDN Magazine, Oct 25, 2001, Design Ideas, page 88.
70_Reference_stabilizes_exponential_current_jpg_72kB
Circuit 71 Low cost
relative humidity transmitter uses single logic IC
The low cost percentage - relative - humidity radio transmitter operates in a
cold storage warehouse for vegetable storage at temperatures of 1 to 5 deg C. It
uses a single 74HC132 chip and a few passive components forming a humidity
controlled transmitter for 10 to 50 MHz RF band. EDN Magazine, Oct 25, 2001, Design Ideas.
71_Low_cost_relative_humidity_transmitter_uses_single_logic_IC_jpg_56kB
Circuit 72 Log amp uses
capacitor charging law
The novel logarithmic amplifier relies on the exponential charging
characteristics of a simple RC circuit and uses popular timer 556 timer (LM556C)
with a few components. EDN Magazine, Jan 10, 2002, Design Ideas, page 71
72_A_Log_amp_uses_capacitor_charging_law_jpg_79kB
72_B_Log_amp_uses_capacitor_charging_law_jpg_47kB
Circuit 73 Extend
the timing capabilities of a PC
When you use internal timing registers and under DOS, a PC cannot easily measure
time intervals with better time resolution than a millisecond. Measuring long
intervals even with this precision is a waste of many CPU cycles. A
microcontroller is well suited for this task, allowing extending timing
precision into the microsesond range for periods from tens of microseconds to
more than 24 hours. This simple circuit uses PICI16F84 drawing only 2 mA, two
capacitors and a 4 MHz crystal. EDN Magazine, Jan 10, 2002, Design Ideas,
page 72
73_A_Extend_the_timing_capabilities_of_a_PC_jpg_91kB
73_B_Extend_the_timing_capabilities_of_a_PC_jpg_116kB
73_C_Extend_the_timing_capabilities_of_a_PC_jpg_66kB
Circuit 74
Optocoupler simplifies power line monitoring
Even if you suppose the ac power line to be free of dc voltage, some types of
loads drain dc currents, thereby introducing a small dc voltage because of
voltage drops in the ac lines. This design goal is to obtain a stable dc voltage
at the output. Thus processor can compute true-rms voltages and currents,
apparent and active power plus power factor. EDN Magazine, Jan 10, 2002, Design
Ideas, page 76
74_A_Optocoupler_simplifies_power_line_monitoring_jpg_88kB
74_B_Optocoupler_simplifies_power_line_monitoring_jpg_142kB
Circuit 75
Improved amplifier drives differential input ADCs
ADCs with differential inputs are becoming popular. Still some gain is required
between the signal source and the ADC. Frequently used amplifiers have only
single output. Presented simple circuits provide dual outputs. EDN Magazine, Jan
10, 2002, Design Ideas, page 80
75_Improved_amplifier_drives_differential_input_ADCs_jpg_148kB
Circuit 76 Circuit
forms dc motor switch with brake
Controling a small dc motor without speed control causes a few problems. Because
of the inductive load and the low starting low starting resistance of the motor,
the switch tends to wear prematurely, with all the related sparks and EMI
problems. More, when you cut the power, the motor continues to rotate for a
certain time, depending on its initial speed and inertia. Presented circuit with
two transistors is very simple and provides enhanced deceleration. EDN Magazine,
Jan 10, 2002, Design Ideas
76_Circuit_forms_dc_motor_switch_with_brake_jpg_124kB
Circuit 77 Circuit
measures small currents referenced to high voltage rails
Designs that need to measure small signals riding on high voltage power rails
suggest the use of isolation devices. However, a high common mode voltage
instrumentation amplifier used with a rail to rail input and output (RIO)
amplifier can recover the signal cleanly and at a much lower cost.
Electronic Design Magazine,
Jan 7, 2002, Ideas for Design
77_Circuit_measures_small_currents_referenced_to_high_voltage_rails_jpg_186kB
Circuit 78 Sorry,
under construction
Circuit 79 Low
power keypad consumes only 100nA
Sometimes one or more keys become "stuck" or are being pressed.
Depending on the circuit design and implementation of the keypad interface, this
condition could cause excess current to flow, thereby draining the batteries in
portable equipment. Presented circuit solves this problem by using a n ultralow
power microcontroller. EDN Magazine,
Jan 24, 2002, page 86, Design Ideas
79_Low_power_keypad_consumes_only_100nA_jpg_189kB
Circuit 80 Autoreferencing
circuit nulls out sensor errors
The circuit nulls out the error of a sensor, such as a pressure transducer, at
its reference level - for example, at ambient pressure. The circuit is an analog
- digital - feedback control system that uses a digitally programmable
potentiometer to provide the variability. EDN Magazine,
Jan 24, 2002, Page 85, Design Ideas
80_Autoreferencing_circuit_nulls_out_sensor_errors_jpg_186kB
Circuit 81 Circuit
provides reference for multiple ADCs
The achievable accuracy for systems with multiple ADCs depends directly on the
reference voltage applied to the ADCs. Often large number of ADCs are organized
in groups of 16, 24, 32 and so on. To obtain maximum accuracy, you need to
minimize errors in the ADCs path. Presented circuits demonstrate dc voltage
references with ultra low noise. For example, such low noise circuit can
drive as many as 1000 ADCs for ultrasound applications. EDN Magazine,
Jan 24, 2002, Page 92, Design Ideas
81_A_Circuit_provides_reference_for_multiple_ADCs_jpg_205kB
81_B_Circuit_provides_reference_for_multiple_ADCs_jpg_219kB
81_C_Circuit_provides_reference_for_multiple_ADCs_jpg_121kB
Circuit 82 Temperature
sensor circuit provides dual slope output
The excellent linearity of intergrated - circuit temperature sensors make them
ideal for direct analog compensation of the thermally induced errors in many
circuits. Additionally, some circuits exhibit a positive temperature coefficient
in one temperature range and negative coefficient on another. One example is the
frequency drift of XT cut crystals, which have a parabolic curve with the center
frequency typically specified at 25 deg C. Presented compensation circuit is
simple and provides dual slope temperature compensation, with only 3 ICs:
LM19, LM61 and LM4041-1.2. Electronic Design Magazine, Jan 21, 2002, Ideas for design, page
51.
82_A_Temperature
_sensor_circuit_provides_dual_slope_output_jpg_229kB
82_B_Temperature
_sensor_circuit_provides_dual_slope_output_jpg_101kB
Circuit 83 Excel
formula calculates standard 1% resistor values
Presented Excle formula calculates the nearest standard 1% resistor value
without using a lookup table or macro. Type or electronically paste presented
formula text into any cell, other than A1. The formula will calculate the
nearest 1% resistor for the value in cell A1. Electronic Design Magazine,
Jan 21, 2002, Ideas for design, page 52.
83_Excel-formula_calculates_standard_1%_resistor_values_jpg_176kB
Circuit 84 Wideband
filter only has two different components
Wideband filters with bandwidths in excess of an octave can be created by
cascading a high pass and a low pass filter. In this design idea, nine pole high
pass and low pass filters have been constructed using a modified equal element
design, with all capacitors being identical and all inductors having same values
as well. Electronic Design Magazine, Jan 21, 2002, Ideas for design, page
54.
84_A_Wideband_filter_only_has_two_different_components_jpg_127kB
84_B_Wideband_filter_only_has_two_different_components_jpg_111kB
Circuit 85 Composite
instrumentation amplifier extends CMRR frequency range 10x
While all instrumentation amplifiers perform well at low frequencies, their
ability to reject common signals usually degrades rapidly as the frequency
increases. A simple solution to this problem exists. Electronic Design Magazine,
Feb 4, 2002, Ideas for design, page 65.
85_Composite_instrumentation_amp_extends_CMRR_frequency_range_10x_jpg_185kB
Circuit 86 Negative
resistance nulls potentiometer's wiper resistance
While almost always called "potentiometers" (which are technically
defined as three terminal variable voltage dividers), many "pots"
actually end up being used as variable resistors (rheostats) instead of. When
used as a variable resistor, all potentiometers - whether electromechanical or
electronic - suffer from the parasitic error of "wiper resistance".
Earlier presented solution "Active cancellation of potentiometer wiper
resistance" in Electronic Design, June 14, 1999,p. 104 was not compatible
with applications requiring potentiometer's both ends available. Presented here
circuit does not suffer from such limitation. Electronic Design Magazine, Feb 4,
2002, Ideas for design, page 66.
86_Negative_resistance_nulls_potentiometer_wiper_resistance_jpg_155kB
Circuit 87 Cross-Trigger
Two Oscilloscopes To Create A Delayed-Sweep Display
Many oscilloscopes lack a delayed-sweep function. Cross-triggering two standard
scopes produces both main and delayed-sweep displays. This double system offers
both main and delayed-sweep traces on every shot, an essential feature for
single-shot work. In contrast, the dual-trace units supplies one of the two
traces, alternately. Electronic Design Magazine, June 10,
2002, Ideas for design, page 97.
87_Cross_Trigger_Two_Oscilloscopes_To_Create_A_Delayed_Sweep_Display_jpg_270kB
Circuit 88 Sampling
Peak detector has shutdown feature
You face a serious problem with using a slow ADC with a fast peak detector.
Presented circuit allows a slow ADC to measure a fast, sampled signal peak. The
100 MHz peak detector for ultrasonic pulse sampling uses a fast MAX4231
amplifier, which amplifier has shutdown feature that facilitates power savings
without loosing the sampled signal. The circuit prevents sampling of another
input peak before a measurement takes place. This feature helps a slow ADC to
monitor a high-speed sampled peak in a desired sampling intervals, an impossible
operation with a conventional peak-detecting circuit. EDN, May 16,
2002, Design Ideas, page 100.
88_Sampling_peak_detector_has_shutdown_feature_jpg_123kB
Circuit 89 Remote
Humidity Sensor Needs No Battery
89_Remote_humidity_sensor_needs_no_battery_jpg_106kB
Circuit 90 Improved
Frequency Modulator Uses "Negatron"
90_Improved_frequency_modulator_uses_negatron_jpg_236kB
Circuit 91 Circuit
Improves Further On First-Event Detector
91_Circuit_improves_further_on_first_event_detector_jpg_124kB
Circuit 92 Differential
Amp Needs No Power source
92_Differential_amp_needs_no_power_source_jpg_107kB
Circuit 93 Switching
Regulator Forms Constant Current source
93_Switching_regulator_forms_constant_current_source_jpg_104kB
Circuit 94 Voltage
To Current Converter drives White LEDs
94_Voltage_to_current_converter_drives_white_LEDs_jpg_155kB
Circuit 95 Circuit
Controls Two LEDs With One Microcontroller Port Pin
95_Circuit_controls_two_LEDs_with_one_microcontroller_port_pin_jpg_239kB
Circuit 96 Add
CAD Functions To Microsoft Office
96_A_Add_CAD_function_to_Microsoft_Office_jpg_208kB
96_B_Add_CAD_function_to_Microsoft_Office_jpg_157kB
Circuit 97 Dual
Gate Inverter Oscillator Saves Power, Boosts LED Brightness
97_Dual_gate_inverter_oscillator_saves_power_boosts_LED_brightness_jpg_246kB
Circuit 98 Circuit
performs high - speed voltage - to - current, current - to current conversion
98A_Circuit_performs_high_speed__voltage_to_current_current_current_conversion_jpg_188kB
98B_Circuit_performs_high_speed__voltage_to_current_current_current_conversion_jpg_288kB
Circuit 99 Linear
power driver works from single supply
99_Linear_power_driver_works_from_single_supply_jpg_163kB
Circuit 100 PC and long
baseline chronography measure ballistic parameters acoustically
100A_PC_and_long_baseline_chronography_measure_ballistic_parameters_acoustically_jpg_93kB
100B_PC_and_long_baseline_chronography_measure_ballistic_parameters_acoustically_jpg_127kB