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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
Canary Sound Effect - An electronic version of a chirping canary. May be used as an alarm, a sound effects generator or perhaps a replacement doorbell __ Designed by Andy Collison
Characterizing & minimizing VCO phase noise - Application Note__ MiniCircuits.com
Cheap Low Power 3v 2hz Oscillator - This is yet another method to generate low frequency output pulses. The circuit uses an inexpensive under-voltage monitor IC and a couple of cheap MOSFETs. It could easily be modified to produce pulse frequencies from about one cycle per minute to a maxim . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
Circuit Biases VCOS for Cable and TV - 11/20/97 EDN-Design Ideas - PLLs are useful in a variety of applications, most notably cable and TV tuners. Design by Ravindra Ambatipudi, National Semiconductor Corp, Santa Clara, CA
Circuit generates clean sine waves - 06/19/97 EDN-Design Ideas - Generating a square wave at a particular frequency is fairly simple. Many techniques for doing so exist, using counters, flip-flops, and--everyone's favorite--the venerable 555 timer. Generating a sine wave, however, is not nearly as simple or inexpensive. Figure 1 shows a technique for generating a high-quality sine wave from a square-wave source Design by Med Dyer, Jabra Corp, San Diego, CA
CD4 069 Atomic Frequency Standard - The CD4069 Atomic Frequency Standard picks up AC "hum" from the surrounding environment to produce an accurate frequency reference. This simple circuit generates 10 Hz and 20 Hz from 60 Hz power grids. A short antenna picks up 60 Hz from the building wiring and applies the signal to a linearized gate, acting as a sensitive amplifier (pins 1 and 2). The 0.1uF capacitor to ground at the junction of the two, 10 Megohm resistors prevent negative feedback from lowering the input resistance, so the amplifier is quite sensitive. The output of the amplifier is applied to the second gate where it is squared up (pins 3 and 4).
__ Contact: Charles Wenzel of Wenzel Associates, Inc.
CMOS
hex inverter generates low-distortion sine waves - 06/09/05 EDN-Design Ideas - Audio signal source uses hex inverter and handful of passives Design by Al Dutcher, West Deptford, NJ
CMOS
Inverter 125khz LC Oscillator - This circuit uses a single CMOS
inverter to form a series resonant LC oscillator. The values shown set the oscillation at about 125KHz but the other frequencies are possible by changing the main LC values. . . Circuit by David Johnson P.E.-March, 2002
CMOS
Inverter forms a Resonant LD Oscillator - This circuit uses a single CMOS
inverter to form a series resonant LC oscillator. The values shown set the oscillation at about 125KHz but the other frequencies are possible by changing the main LC values . . . Hobby Circuit designed by David A. Johnson P.E.-March, 2002
CMOS
Inverter Parallel LC Oscillator - I have used this parallel resonant LC oscillator circuit countless times. The oscillator frequency is determined by the inductor and capacitor values. I have shown an adjustable inductor to make it easy to set the frequency to a specific value. . . Circuit by David A. Johnson P.E.-March, 2002
CMOS
Inverter VCO tunes octave to UHF - 11/19/98 EDN-Design Ideas - NOTE
: File contain several designs. Scroll to find this one. A robust and versatile vco provide as a stable output to 300 MHz (Figure 1). The circuit's simplicity, unconditional stability, and consistent high-drive capability over an octave make the oscillator ideal for many applications, such as synthesized sources, local oscillators, and transmitters. The AHC logic family (Texas Instruments, www.ti.com) makes the circuit's performance possible. AHC is a relatively new line of CMOS
logic whose high speeds and good noise performance allow oscillator operation into regions in which bipolar-junction-transistor and FET designs prevail. Design by Shawn Stafford, AM Communications Inc, Quakertown, PA
CMOS
Inverters Form 125Khz Oscillator - This circuit inverts the LC components so the inductor is grounded. Two inverters are needed to produce the needed oscillation. Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies . . . Hobby Circuit designed by David Johnson P.E.-March, 2002
CMOS
Nand Gate Forms Gated 125Khz Oscillator - This circuit is uses a NAND gate as an inverter. The gate allows the oscillator to be gated on and off. Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies. . . Circuit by Dave Johnson P.E.-March, 2002
CMOS
Oscillator, Draws Only 0.5ua - If truly low power oscillators interest you, this circuit draws a mere 2 microwatts (500nA) from a 6v battery. It uses a very inexpensive C-MOS IC to produce a frequency of 2Hz. However, by changing the component values you can push it to 300Hz . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
CMOS
Schmitt Trigger IC Makes VCO - By changing the supply voltage fed to a classic 4584 Schmitt trigger type oscillator, the oscillator frequency can be changed over a range of 50:1. A 74HCU04 inverter is used at the output of the 4584 to maintain a constant TTL logic level signal. . . Circuit by Dave Johnson P.E.-December, 2002
Collection of Audio Oscillators - Collection of audio oscillator circuits. __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Constant Reactance Voltage Controlled Oscillator - For some time railroad companies have been wrestling with the problem of tracking rail cars. This has traditionally required manual log entry of identification numbers displayed on the cars as they pass through the switching yard. __ Designed by Raymond T. Page, Reprint courtesy of RF Design Magazine
Compensation Extends Oscillator's Range - 12/05/96 EDN-Design Ideas - A simple technique provide as phase compensation for the oscillator in Figure 1a. In this circuit, a tungsten lamp regulates the amplitude of a crystal bridge oscillator. This type of oscillator produces a very low-distortion output at a very stable frequency. The op amp must have a negligible phase shift at the operating frequency, which Design by Israel Schleicher, Green Spin, Bakersfield, CA
Constant Temperature - This circuit is a generic low power temperature controller that can be used for stabilizing temperature sensitive electronic circuits. It was built to stabilize a radio frequency VFO (Variable Frequency Oscillator) for ham radio applications. The circuit has also been used to lower the drift of a Ramsey FM10a micropower FM transmitter __ Designed by G. Forrest Cook
Continuous Coverage V.F.O. for H.F. - Timing and oscillator circuit diagrams / circuit schematics __ Designed by Francesco Morgantini IK3OIL
Convert any signal to exactly 50% duty cycle - 06/25/13 EDN-Design Ideas - How would you process a variable frequency signal to always maintain a 50% duty-cycle? Here's one way Design by Jim McLucas
Convert periodic waveforms to square waves - 08/16/01 EDN-Design Ideas - 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 valuable when the square wave's duty cycle is variable and controllable. Figure 1 shows a circuit that has these attributes and can drive several TTL-compatible loads Design by Ron Mancini, Texas Instruments, Bushnell, FL
Crystal Controlled 1KHz Signal Generator - A while back I got an email from a Discover Circuits visitor. He needed a way to calibrate a RPM display for a big diesel engine. The engine had a tachometer output which produced 12 pulses per rotation with an amplitude of about 5v RMS. The full scale reading on the engine’s RPM speed display dial was 5, 000. . . Circuit by David Johnson P.E.-May, 2012
Crystal heater / temperature stabilization (TXCO) - OK, here is the circuit I used - See image below. The original National Semiconductor circuit had a 30 K resistor in series with a 400 µF cap., both in parallel with the 100 K resistor on the input of the 1st LM324 section. I found that combo to actually destabilize the operation of the controller for this particular application, so I removed them & changed the 2 µF cap in series with the 10 Megohm resistor to 5 µF.__ Bob Dengler NO6B
Crystal Oscillator overcomes typical Drawbacks - 08/17/98 EDN-Design Ideas - NOTE
: File has several circuits, scroll to this one. Most crystal oscillators suffer from three drawbacks: They can't drive much of a load, the duty cycle isn't adjustable, and the duty cycle drifts. The crystal oscillator in Figure 1 solves these problems. Three parallel gates drive heavy loads, the duty cycle is adjustable from 25 to 75%; and feedback minimizes the drift. Design by Ron Mancini and Jeff Lies, Harris Semiconductor, Melbourne, FL
Crystal-Based 50hz Generator - Here is a simple oscillator circuit that generates 50Hz frequency using a crystal. It produces alternating 50Hz pulses with 50 per cent duty cycle, which can be used in inverter circuits....__ Electronics Projects for You
Crystal-Oscillator Is Ultralow Power - EDN-Design Ideas -- 09/24/12 Build a crystal-oscillator circuit that draws only about 5 μA of current. Design by Thomas Mathews, Texas Instruments
Current-Feedback Amp Yields Simple Circuit Oscillator - 06/08/95 EDN-Design Ideas - Using a current-feedback op amp, you can generate high-frequency sine waves with larger amplitude than conventional op-amp-based designs. The circuit in Fig 1 uses four passive components, connecting one capacitor to the compensation node (another op amp that has this pin a Design by
Celma and P A Martinez, University of Zaragoza, Spain
Current-Feedback Amps Square Up Fast Signal - 06/23/94 EDN-Design Ideas - Using current-feedback amplifiers to convert signals from sine waves to square waves for DSP confers advantages over the more common comparator approaches. Current-feedback amplifiers have wide bandwidths and relatively small and constant propagation delays. These small, constant delays help meet the setup-and-hold requirements of Design Rea Schmidt, Comlinear Corp, Fort Collins, CO
DAC & Op Amp provide variable-control voltage - 12/06/01 EDN-Design Ideas - Early DACs contained standard R-2R ladder networks, and produced a negative output voltage. These early DACs, such as the MAX7837/7847 and the MAX523, require both positive and negative supply rails to accommodate their negative output. With the transition to single-supply ICs, however, many modern DACs operate with a single supply rail and an inverted R-2R ladder network Design by Chad Olson, Maxim Integrated Products, Sunnyvale, CA
DDS/PLL based VFO synthesizer - Timing and oscillator circuit diagrams / circuit schematics __ Designed by Aleksander Stare
Design & Construction of Radio Frequency (RF) Oscillators - Every oscillator has at least one active device (smarties don't complicate matters for me - just read on) be it a transistor or even the old valve. This active device and, for this tutorial we'll stick to the humble transistor, acts as an amplifier. There is nothing flash about that. For this first part of the discussion we will confine ourselves to LC Oscillators and I'll keep the math to an absolute minimum.__ Ian Purdie
Design features of a synthesizer using Mini-Circuits VCOs - Application Note__ MiniCircuits.com
Designing VCOs & Buffers using the UPA family of Dual Transistors 3/99 - App Note Doc #927__ California Eastern Laboratories
Digital Radio Mondiale (DRM) - Modification of my Yaesu FT-897 transceiver and building of a 467 kHz IF mixer to make a complete working DRM receiver system (made in the beginning of 2005) __ Designed by Bjarke Korsgaard
Digital Signal Controls Sine Generator - 05/15/03 EDN-Design Ideas - The circuit of Figure 1 produces an accurate, variable-frequency sine wave for use as a general-purpose reference signal. It includes an eighth-order elliptic, switched-capacitor lowpass filter, IC3, which uses a 100-kHz square-wave clock signal that microcontroller IC2 generates. (Any other convenient square-wave source is also acceptable Design by Simon Bramble, Maxim Integrated Products, UK
Digital Signal Processor DSP for Radio Communications - The W9GR DSP-3 is an improved low cost digital signal processor for radio communications use. It features 18 DSP functions, a LED display, and 13 bit audio precision__ Quantics
Digital signals produce pure sine waves - 10/09/97 EDN-Design Ideas - Analog oscillators produce excellent sine waves but are temperamental and hard to design. They also require extensive redesign every time you change the oscillation frequency. Digital oscillators. Design by Ronald Mancini, Harris Semiconductor, Melbourne, FL
Direct Digital Synthesis VFO for HF Bands-based on Analog Devices AD7009 DDS - Timing and oscillator circuit diagrams / circuit schematics __ Designed by Francesco Morgantini IK3OIL
DPP adds versatility to VFC - 14-Nov-02 EDN-Design Ideas - The basic VFC (voltage-to-frequency converter] in Figure 1 comprises an integrator (IC1] and a Schmitt-trigger circuit (IC2]. The integrator converts the dc input voltage, VIN , to a linear voltage ramp, and the Schmitt trigger sets the limits of the integrator's output voltage. Feedback around both circuits provide as the condition for oscillation Design by Chuck Wojslaw, Catalyst Semiconductor, Sunnyvale, CA
Dramatically Increase the Frequency Range Of RC-Based Voltage-Controlled Oscillators - 09/21/12 EDN-Design Ideas - Add a varactor to a voltage-controlled oscillator to increase the tuning range. A typical voltage-to-frequency converter—also known as a VCO (voltage-controlled oscillator) —IC has a simple linear tuning characteristic relating input voltage to output frequency. It is usually of the form F=kV/RC, where RC is the time constant of the associated timing resistor and capacitor. The output frequency range of these parts varies, but few, if any, tune over the entire range with one set of RC timing components. If you change the timing ratio as the input voltage changes, however, you can magnify the tuning range to take advantage of nearly the entire frequency range in one implementation. Design by Shawn Stafford, Pittsburgh, PA
DSP-10 transceiver project - DSP-based 2m transceiver controlled by a Personal Computer (made in June 2001) __ Designed by Bjarke Korsgaard
DSSSE - Type 1 (Voltage Controlled) Solar Engine - If you had time to experiment with the ALF type SE circuit you may have discovered some of its shortcomings with regard to a Power Smart Head adaptation. The problem is that HCMOS
gates are power hungry when used as SE voltage comparators when the analog input voltage is near the CMOS
switching threshold. If an HCMOS
gate is used without sampling, the chip supply current can be as high as 70mA with the comparator input voltage near the trigger threshold (Vcc / 2). __ Designed by Wilf Rigter
DTMF Coder Makes Low-Cost Sine-Wave Generator - 10/13/94 EDN-Design Ideas - A telephone DTMF IC produces, by design, two tones if you connect a single intersection of the IC's 4[x]4 keypad matrix (Fig 1]. (Telephones commonly have 3×4 keypads but, unknown to many people, the applicable standard allows for a fourth row of four keys. ]But, if you connect two key inputs at once, the IC produces a single-frequency, Design by Criscuolo Anna Rita, Labtec Telecommunications, Nichelino, Italy
Dummy Alarm - This project makes a superbright LED flash briefly once every 5 seconds to imitate the indicator light of a real alarm. The circuit is designed to use very little current to prolong battery life so that it can be left on permanently. This is a simple project, ideal for a beginner __ Designed by John Hewes
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