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Signal Generator Circuits

Signal Generators:  #'s - B        C - L       M - S       T - Z
 

Last Updated: November 22, 2021 02:41 PM

Circuits Designed by Dave Johnson, P.E. :

Advertising Badge #1 with Flashing LED -  I have seen numerous flashing light badges at trade shows and conventions.  They are often handed out as gifts to promote some business.  The devices often use inefficient circuits, which cause the battery power source to be quickly depleted. . . Circuit by Dave Johnson P.E.-March, 2002

Advertising Badge #2 with Flashing LED -  This circuit uses a CD4013 dual D Flip/Flop IC .  A single lithium battery will provide months of continuous LED flashing.  it also has a tiny push-button switch to turn on and off the light flashing. . . Circuit by David Johnson P.E.-March, 2002

Astable Multivibrator with Very Low Power -  This classic circuit draws only 200 nanoamps from a 1.5v supply . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

Astable Ultra Low Power Multivibrator -  Taking advantage of some new voltage comparators, this circuit can produce a nice square wave signal while drawing only 1.6 micro amps.  With the inclusion of a diode, the circuit can also produce short pulses instead of a square wave signal . . . Hobby Circuit designed by David Johnson P.E.-December, 2004

Automatic Timeout included with this On/Off Flip/flop Circuit -  This circuit is ideal when a device needs to be turned on and off with a single pushbutton switch, but also needs to turn itself off after some period of time.  With the components shown, the output will stay on for only about 20 seconds . . . Hobby Circuit designed by David A. Johnson P.E.-May, 2012

Battery-Powered LED Flashing Advertising #2 -  This circuit is similar to flashing LED advertising badge #1.    it uses a CD4013 dual D Flip/Flop IC .    The 74HCT74 IC in #81 does not always work.    As in #81, a single lithium battery will provide months of continuous LED flashing. . . . Hobby Circuit designed by David Johnson P.E.-March, 2002

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Links to electronic circuits, electronic schematics and designs for engineers, hobbyists, students & inventors:

A Low distortion Audio Signal Generator -  Scroll down.  The next circuit (above) is a better implementation of the Wien circuit: this uses the Wien in the normal fashion, in the positive feedback path and with negative feedback to maintain stability.  The device marked Th1 is a glass bead type thermistor: some of these thermistors consist of a bead in an evacuated glass envelope and they are designed specifically for amplitude stabilization in such circuits.  if necessary the 100R can be altered to suit various thermistors (and to trim the amplitude).   __ Designed by Richard Torrens

A Low-Frequency Crystal Controlled Oscillator -  The RF engineer sometimes has to look for an instrument that will check a low frequency quartz crystal unit reliably and rapidly.  This is a difficult piece of equipment to find and the engineer often has to consult an electronic circuits handbook for the schematic of a circuit that will perform the task.  Unfortunately __ Designed by Ramon Vargas

A Practical Twin-T Oscillator -  Scroll down.  Perhaps the first thing that will strike you (if you have met the twin-T before) is that the input to the twin-T (from the bulb) is actually fed into the foot of the network and output is (as you might expect) from one arm (into the base of the transistor) but the other arm is earthed.  Now hold on a minute: an emitter follower has no voltage gain __ Designed by Richard Torrens

A Practical Wien Oscillator -  Scroll down.  The second circuit is a practical implementation of a Wien oscillator but in this the Wien network is inverted.  it is the 'wrong way up' and in the negative feedback path.  Positive feedback is applied via the 500R preset to make it oscillate.  And there's a nice incandescent light bulb to show that it's working __ Designed by Richard Torrens

A Ramping & Displaying on an LM3914 -  Could be used for a Turn Signal indicator.  Also includes an additional Circuit and PCB for Driving Higher Power Lights.   __ Designed by G.L. Chemelec

A Weighting Filter for Audio Measurements -  For noise measurements.  ideal for use with the AC Millivoltmeter above   __ Designed by Rod Elliott  ESP

Accurate 1hz Generator -  Accurate 1Hz squarewave pulses are required in stopwatches and other digital circuits.  Here is a low-cost, general-purpose 1Hz signal generator without using a crystal oscillator.230V, 50Hz, single-phase AC mains is stepped...__ Electronics Projects for You

Advertising Badge #1 with Flashing LED -  I have seen numerous flashing light badges at trade shows and conventions.  They are often handed out as gifts to promote some business.  The devices often use inefficient circuits, which cause the battery power source to be quickly depleted. . . Circuit by Dave Johnson P.E.-March, 2002

Advertising Badge #2 with Flashing LED -  This circuit uses a CD4013 dual D Flip/Flop IC .  A single lithium battery will provide months of continuous LED flashing.  it also has a tiny push-button switch to turn on and off the light flashing. . . Circuit by David Johnson P.E.-March, 2002

ALD555 Oscillation -  Circuit ideas for Designers App Note__ Advanced Linear Devices, Inc

Amplitude-Stable Oscillator Has Low Distortion, Low Cost -  11/09/00 EDN Design Ideas:  The multivibrator is a common circuit that consists of an amplifier with both positive and negative feedback (Figure 1a).   When the output is positive, the positive.   PDF contains multiple circuits, scroll to find the one of interest Design by Moshe Gerstenhaber, Chau Tran, and Mark Murphy, Analog Devices Inc,Wilmington, MA

An Inexpensive Tone Encoder -  Figure 1 illustrates an easy circuit that can be constructed with mostly Radio Shack parts on any general purpose circuit board.  The only rigid requirement is that capacitor C1 be stable over a wide temperature range.  Use only Mylar, Polyester or Metal film for capacitor C1.  The frequency is determined by the following formula: FREQUENCY = 1/R1C1The specified values should allow any tone between 100 to 300 Hz.  increase R1 or add another resistor in series with R1 for lower tone frequencies __ Designed by Radio Amateur Society of Norwich

An Oscillator Sawtooth & Square Wave Output -  Simple, Single Supply and Works Very well with Minimum Parts Count.   __ Designed by G.L. Chemelec

Analog LED Bar VU Meter -  The circuit was designed to work with an audio power amplifier which operated off +18v-0v-18v power rails.  The actual voltage used is not too critical except that the feedback is referred to the LED chain which itself is anchored to a +12v rail, hence the separate stabilizer __ Designed by Richard Torrens

Analog switch converts 555 timer into pulse-width Modulator -  15-Feb-07 EDN Design Ideas:  Added CMOS switch enhances a PWM oscillator Design by Jordan Dimitrov, Tradeport Electronics, Vaughan, ON, Canada

Anton Chekhov -  My LO strategy involved mixing a 16.93 MHz xtal oscillator (xtal Q = ~100K) with a 3.121 to 3.216 MHz Hartley L-C VFO.  I planned to use the EMRFD Figure 4.24 method to extract low noise + distortion from the xtal oscillator and mix it with the VFO signal in a Gilbert cell mixer like the NE612. __ Contact Vasily Ivanenko

Archery timer -  in FiTA-style archery tournaments there are rules to the timing of the event.  From the 2000 FiTA rulebook here are the rules that the timer must serve __ Designed by A. Ron Carmichael

Astable Mode Operation 50% Duty Cycle -  Circuit ideas for Designers App Note__ Advanced Linear Devices, Inc

Astable Mode Operation Free Running Oscillator -  Circuit ideas for Designers App Note__ Advanced Linear Devices, Inc

Astable Multivibrator with Very Low Power -  This classic circuit draws only 200 nanoamps from a 1.5v supply . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

Astable Ultra Low Power Multivibrator -  Taking advantage of some new voltage comparators, this circuit can produce a nice square wave signal while drawing only 1.6 micro amps.  With the inclusion of a diode, the circuit can also produce short pulses instead of a square wave signal . . . Hobby Circuit designed by David Johnson P.E.-December, 2004

Audio Sweep Oscilator -  This circuit was designed for a sound effect, but may serve other useful purposes when a basic, swept-frequency audio source is required.  it produces both square and triangular wave outputs that ascend from about 80 to 730 Hertz in a repeating cycle of about 12 seconds.  Appropriate component-value substitutions will yield variations in these parameters.  Operation is as follows:Operational amplifier U2B and its associated components form an astable multivibrator with __ Designed by Arthur Harrison

Audio Test Oscillator -  As a piece of test equipment, an audio oscillator has to be considered essential for anyone working in with hi-fI gear.  Together with an audio millivoltmeter (as described in Project 16) , and even better if you have access to an oscilloscope, you will be able to make proper measurements on everything from preamps, RiAA equalisation stages (for vinyl disks) , tone controls, crossover networks, etc __ Designed by Rod Elliott  ESP

Auto pulse generator senses & responds to a probed load -  02/25/13  EDN Design Ideas:  Use this handy pulse generator to inject momentary power pulses into a circuit under test.   Design by Raju Baddi

Automatic Timeout included with this On/Off Flip/flop Circuit -  This circuit is ideal when a device needs to be turned on and off with a single pushbutton switch, but also needs to turn itself off after some period of time.  With the components shown, the output will stay on for only about 20 seconds . . . Hobby Circuit designed by David A. Johnson P.E.-May, 2012

Band-pass Network -  Circuit ideas for Designers App Note__ Advanced Linear Devices, Inc

Basic RF Oscillator #1 -  This circuit switches a relay at dark via a Light Dependent Resistor or LDR for short.  The applications are numerous.  in my application, it switches on a light with an older type movement sensor and is mounted on the top corner of my workshop with the LDR facing upwards.  The Dark Activated Relay prevents that the light is triggered during daylight hours.  But, it can also be used to switch led-beacon lights for your driveway, or whatever __ Designed by Tony van Roon  VA3AVR

Battery-Powered LED Flashing Advertising #2 -  This circuit is similar to flashing LED advertising badge #1.    it uses a CD4013 dual D Flip/Flop IC .    The 74HCT74 IC in #81 does not always work.    As in #81, a single lithium battery will provide months of continuous LED flashing. . . . Hobby Circuit designed by David Johnson P.E.-March, 2002

BER Tester Measures Errors in Low-Data-Rate Applications -  12/05/05  EDN Design Ideas:  You don't need an expensive pattern generator to produce a PRBS (pseudorandom-bit-sequence] signal for making elementary BER (bit-error-rate] measurements in low-data-rate continuous-transmission systems Design by Cedric Mélange, Johan Bauwelinck, Jo Pletinckx, and Jan Vandewege, Ghent University, Ghent, Belgium

Bipolar current source maintains high output impedance at high frequencies -  12/05/05 EDN Design Ideas:  Use line-receiver/amp ICs  to build high-frequency constant-current sources Design by Alex Birkett, University College London, Hospital National Health Service, London, UK

Bistable Flip flop -  Here are two examples of bistable flip flops which can be toggled between states with a single push button.  When the button is pressed, the capacitor connected to the base of the conducting transistor will charge to a slightly higher voltage.  When the button is released, the same capacitor will discharge back to the previous voltage causing the transistor to turn off.  The rising voltage at the collector of the transistor that is turning off causes the opposite transistor to turn on and the circuit remains in a stable state until the next time the button is pressed and released.   __ Designed by Bill Bowden

Build a PIC Controlled DDS VFO 0 to 6 MHz -  This is NOT meant as a detailed building instruction for a DDS VFO.  it is only a few fragments from my experimental work in the shack.  This is "as is" information.  it may contain errors.   However, my own prototype works very well. __ Designed by Johan Bodin, SM6LKM

Build a Simple Circuit Complementary-Bracket-Pulse Generator -  20-Aug-09 EDN Design Ideas:  When building push-pull switching power converters or motor controllers, you often need alternating pulses with a small amount of dead time between them to minimize simultaneous conduction in output-switching devices.  Switching controller ICs  have this feature, but they usually operate Design by Horst Koelzow, Global Thermoelectric, Calgary, AB, Canada

Build a UWB Pulse Generator On an FPGA -  06/23/11  EDN Design Ideas:  Make pulses that reach twice an FPGA's clock frequency.  You can implement a digital UWB (ultrawideband) pulse generator in most FPGAs.  The design lets you create a pulsed signal with a frequency that’s twice the FPGA’s clock frequency (Figure 1).  A previous design relies on asynchronous delays to make pulses of the desired frequency.  That design, however, requires an FPGA that supports tristate pullups, such as the Xilinx Virtex 2 (Reference 1).   Design by Punithavathi Duraiswamy, Xiao Li, Johan Bauwelinck, and Jan Vandewege, Ghent University, IMEC/Department of Information Technology, Ghent, Belgium

Bus-Request Signal Generates Logic Waveform -  06/20/96 EDN Design Ideas:  The scheme in Figure 1 generates accurate and repeatable logic sequences—even in  presence of interrupt activity.  Specifically, circuit generates 16-bit logic sequences with a resolution of 100 nsec.  This circuit's repeatability is an advantage compared with or sequence-generation methods Design by Dhananjay Gadre, IUCAA, Pune, India

Button Battery Cell Internal Resistance Measurement Circuit -  The open cell voltage of a small silver oxide button cell battery remains very close to 1.5 volts over most of the life of the cell.  However, there is a relationship between battery health and the internal resistance of the cell.   This circuit when used. . . Circuit by Dave Johnson P.E.-July, 2006

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Signal Generators:  #'s - B        C - L       M - S       T - Z


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