New Circuits Page 225
- Page 225
-
A filter with a band-reject characteristic is frequently referred to as a notch filter. A typical circuit using a µ 741 is the unity-gain configuration for this type of active filter shown. The filter response curve shown is a second-order band-reject....
-
-
Component value sensitivityis extremely critical, as are temperature coefficients and matching of the components. Best performance is attained when perfectly matched components are used and when the gain of the amplifier is unity..
-
Rl and R2 hold the inverting input at half supply voltage. R4 applies feedback to increase the input impedance at pin 3. Pin 3, the nonin-verting input, is connected to the junction of R3 and C. After the switch is opened, C charges via R3. When the....
-
The time base is first selected with Sl set for seconds or minutes, then units 0-99 are selected on the two thumbwheel switches S4 and S5. Finally, switch S2 is depressed to start the timer. Simultaneously, the quartz crystal-controlled divider circuits....
-
The light sequencer uses two ICs and 10 SCRs to create.an ac sequencer. The first 10, a 555 timer, is used to provide clock pulses for 102. The 10 is configured as an astable multivibrator, and its output is on pin 3. Capacitors CI and 04, along with....
-
The present document shows step by step how to easily build an interesting pointing device: the wireless tilt mouse, that allows to control the mouse?s cursor on the PC screen through the tilt of the board itself. The analog data from a 3-D accelerometer and....
-
-
Notes: LM3909, Capacitor, and LED are Installed in a White Translucent Cap on the Flashlight"s Back End. Only One Contact Strip (in Addition to the Case Connection) is Needed for Flasher Power..
-
Most amps acoustic frequencies that make our readers, instead of a transformer power, sometimes required two or sometimes three. This tactic is more common in amplifiers 'High-End', where the altar of high fidelity are all eager to sacrifice their economies.....
-
ICl, an Intersil ICL 7106, contains an aid converter, a 3,1/2-digit LCD driver, a clock, a voltage reference, seven segment decoders, and display drivers. A similar part, the ICL7107, can be used to drive seven segment LEDs. The probe body is a five-inch....
-
This high-voltage pulse supply will generate pulses up to 30 kV. Ql and Q2 form a multivibrator in conjunction wi..
-
The circuit presented this month is a basic configuration of the very versatile 4017 IC Chip. In the most common use of the IC, it will turn on 10 separate outputs sequentially. Typically, the circuit is used to turn on a LED for certain time cycle. In the....
-
-
A few designs for remote control switches, using VG40T and VG40R remote control pair, are shown here.
The miniature transmitter module shown in Fig. 1, which just measures 34 mm x 29 mm x 10 mm, can be used to operate all remote control receiver-cum-switch....
-
This circuit as first published in Wireless World September 1975 and subsequently in MECRM. It's built around a TTL quad NOR gate, though CMOS could be used...
-
When switch SWl is positive, the FET is turned on, and has a resistance of about 400 ohm. The input voltage charges up the capacitor through the FET. When SWl is negative, the FET is turned off (pinched off). To get a long storage time, the op amp must have....
-
The circuit in Figure 1 implements a low-cost, micropower, latching motor controller that uses current sensing rather than switches to stop the motor. The design is optimized for a supply voltage of 3 to 9V, making it well-suited to battery-powered....
-
The design in Figure 1 is a visible optical link for those who need to see the transmitted data. An isolation figure of more than 5000V is a bonus. Tests of the system used the COM input of a data-acquisition system, as well as a standard PC`s COM port. The....
-
Figure 1 shows distortion variations in red and violet. Notice how the violet wave follows the green wave perfectly during its positive excursion but falls short of the mark during the negative swing. The red wave is more symmetrical, but does not "clip"....
-
The following are LM555 timer circuits that have unusual functions. Designed to time a sports event; In this circuit the GREEN output is adjusted to be on for 3 minutes and then the RED output is set for 1 minute in a repeating cycle. Each time the light....
-
The LM1812 is a complete ultrasonic transceiver on a chip designed for use in a variety of pulse-echo ranging applications. The chip operates by transmitting a burst of oscillations with a transducer, then using the same transducer to listen for a return....
-
The GHF1 is a small generator covering the HF and LF band from 30 Hz to 30 MHz in 6 ranges. The sinusoidal signal obtained can be amplitude modulated (AM) or frequency (FM).
The GHF1 also has a sweep function.
An LCD display 2 x 16 characters allows the....
-
This circuit was described in a recent edition of an amateur radio magazine. It allows operation in the 160- to 190-kHz band with up to 1 W (license free) in any mode (CW/SSB/FM, etc.) It consists of a receiving converter for 5 kHz to 450 kHz and a....
-
A VOX is a voice-operated switch that is often used as a substitute for the press-to-talk switch on" a microphon..
-
Figure 1 shows a typical dual battery charger. This circuit
can charge batteries with up to 4A and switch continuously
down to zero load currents. This circuit takes advantage
of ceramic capacitors space saving features without producing any audible....
-
A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist`s workbench. This circuit is not an absolute novelty, but it is simple, reliable, "rugged" and short-proof, featuring variable voltage up to 24V and variable current....
-
This project was designed and constructed as enhancement to the 0-30V Stabilized Power Supply Project with the DIY electronics hobbyist in mind. The circuit uses a single PIC Microchip to perform the Voltage, Current and Temperature conversions and display....
-
The use of pulse width modulation (PWM) is common for the use of controlling power to a particular electrical device. Motor speed control, LED contrast control, power supplies are some of the example usage of PWM. 18 series PIC always come with a CCP module....
-
I had been putting off writing a driver for some 24LC64 and 24LC256 EEPROMS I was thinking about using, when I came across a temperature logger application written by Seal Ellis. The Temperature logger was posted on on www.avrfreaks.net on January 10, 2002,....
-
Three individual flashing circuits that use an LM3909 LED flasher/oscillator IC create the appearance of a pseudo-random firing order. The combination of CX!RV C.JRb, and C^R control the blink rate, which is between 0.3 and 0.8 s, and the inherent wide....
-
This Nicad battery tester discharges the test battery at a rate of 500 mA. When the endpoint of 1 V (determined by set..
-
The figure illustrates a reversible de motor drive application with adjustable speed control. The D inputs for these drivers are complementary and can be tied together and driven from the same logic control for bidirectional motor drive. The enables are....
-
The peak output voltage will be approximately 15,000 to 20,000 volts, but this will vary with the ignition coil type and the voltage at which the MOV starts conducting. Do not touch any part of the 555 circuit including any leads of the timing resistors or....
-
The waa-waa effect is achieved as certain frequencies are amplified more than others. A phase shift RC oscillator makes up the basic circuit. Negative feedback is obtained by feeding part of the signal back to the base. When adjusting initially, RV1 is....
-
A serial interface and bias supply for the Seiko-Epson G1216N000 using an AT90S2313 because there just aren't enough applications examples for this display on the web. The display is a pretty old transflective gray mode TN LCD design with ok, but not great....
-
It was designed for use on a "The London Model Railroad Group`s" large O scale layout located at London, Ontario, Canada. The prime requirements for the club throttles were that they be rugged, reliable and produce as little heat as possible. Throttles of....
-
This circuit detects brief shorts or opens. When S2 is in the up position, the circuit indicates if there is or..
-
In an adjustable lowpass filter, each filter section uses commonly available components (Figure 1). This example uses filter-section cutoff frequencies for standard inductors and capacitors without the need for any extra components in series or parallel.....
-
Using this low cost Project one can reproduce AUDIO from TV without disturbing anyone. It does not use any wire between TV and HEADPHONE. In place of pair of wires it uses invisible Infrared light to transmit audio signals from TV to Headphone. Without using....
-
Earphones, batteries are sold separately. AM / FM seems to be a common mold. But stamping is different. AM / FM E193577 UL94V0 board with the AM / FM etching printed circuit board manufacturers are the same. Shape is considered to be shared. (Design, sharing....
-
This low-power converter will supply about 100 mW of dc to a load and it is useful to isolate or derive dc voltages. It operates at around 200 kHz. LI is wound on a 22-mm diameter 13-mm high pot core with #32 magnet wire. The primary is 80 turns and the....
-
The PIC 12F629 and 12F675 devices have an internal 4Mhz oscillator that enables the devices to be used without an external crystal or RC network. This frees up one or two pins for I/O use and allows the device to be built into minimum component count....
-
The circuit warns car drivers when the air temperature close to the ground approaches 0°C, thereby indicating possible formation of ice on the road surface. Op amp A1 is wired as a voltage level sensor. Op amp A2 is wired as an astable multivibrator which,....
-
The circuit in Fig. 56-lla lights the signal lamp upon detecting a line current consumption of more than 5 mA, and handles currents of several amperes with appropriate diodes fitted in the D1 and D2 positions. Transistor T1 is switched on when the drop....
-
When we step on the car' s brake, then together with the classic rear STOP ,the third STOP which is situated in the middle of the back half of the car also switches ON. This is the classic function , is to be found in all modern cars. The difference with the....
-
The generator described here is intended for multiburst signal square waveform generation and can be used as a device for characterizing the response of TV monitor amplifiers as shown. The circuit is an RC oscillator with NAND gates (IC4-4011), with its....
-
The compact high performance 4 x 4 crosspoint shown in Figure 1 uses four LT1205s to route any input to any or all outputs. The complete crosspoint uses only six SO packages, and less than six square inches of PC board space. The LT1254 quad current feedback....
-
This circuit is designed to be used in conjunction with the standard 4 foot square loop used in MW for long distance reception...
-
This device allows one or more lamps to illuminate at sunset and turn off at dawn.
Q1 and Q2 form a trigger device for the SCR, providing short pulses at 100Hz frequency. Pulse duration is set by R2 and C1...
-
If load current requirements are relatively low (i.e. maximum forward rms current 500 mA), an ac solid state relay can be constructed quite simply by the connection of two H11C optically coupled SCRs in a back-to-back configuration as illustrated.
..
-
Not every new use of technology requires a microcontroller. This one uses a 12 volt computer fan from CompUSA, a snap close food box from Walmart, some PVC pipe from Home Depot, and a large plastic storage container from Big Lots.e food storage box whose lid....
-
A bridge circuit consisting of two SCRs and two silicon rectifiers furnishes full-wave power to the motor. Diodes, D3 and D5, supply dc to the trigger circuit through dropping resistors, Rl. Phase delay of SCR firing is obtained by charging C2 through....
-
With the advent of HDTV and DVD video, there is a
renewed focus on RGB and color-difference component
video to maximize picture quality. LCD displays have also
entered the mainstream for high-end and portable computer
displays. These applications often....
-
Filter Wiz PRO active filter designer version 4 has just been released. Version 4 represents a major advance in the rapid design of stable and effective active filters...
-
Although labelled as distortion, this is a soft clipping device, using germanium diodes. It's a good example of how little you need for a good basic sound. You could easily swap (or switch) these diodes to silicon types for hard clipping. Not necessarily the....
-
I have received countless emails asking for a circuit to tell the user which car won in a pine car (also called Pinewood Derby, Cub Car, Scout Car, etc.) race. This simple circuit takes care of the guesswork, lighting the appropriate LED to indicate the....
-
A composite configuration greatly reduces de errors without compromising the high-speed, wideband characteristics of HA-2539. The HA-2540 could also be used, but with slightly lower speeds and bandwidth response. The HA-2539 amplifies signals above 40 kHz....
-
This circuit has an overall gain of 320. More gain can easily be obtained by lowering the value of R2. Untrimmed Vas is 10 11V. and Vas tempco is less· than O.lJIV/°C. ..
-
A 555 timer (IC1) generates a 120-Hz signal that is fed to a CD4013BE flip-flop (ICl-a), which divides the input frequency by two to generate a 60-Hz clocking frequency for the FET array (Ql through Q6). ..
-
This circuit can be easily powered from a 1.5 volt battery. One characteristic of N type negative resistance devices is that they typically require a very low bias source resistance in order to keep the bias voltage stable within the negative resistance....
-
The Model HC 6 Headphone Console is a six channel headphone amplifier, consisting of six stereo amplifiers, two master stereo inputs and six individual stereo inputs. The two master stereo inputs feed a separate left and right bus to each of the six....
-
As Ron suggests, controlling the output voltage from a regulator can be made variable in three ways. Using a fixed reference zener diode to increase the output by the value of the zener. A variable resistor for variable output, note that a voltage less than....
-
Most of the CDROMS available have an Audio-Out Output to either plug in the headphones or connect it to an amplifier.
This circuit enables one to use the CDROM as a stand alone Audio CD player without the computer.
This circuit is nothing but a power....
-
The circuit in Figure 1 shows an example of how you can use an integrated switching regulator (ISR) to efficiently vary the speed of a permanent-magnet dc motor. In this application, the rotating head of a robot senses the presence of an oncoming object....
-
The electronics consist of three op-amp circuits; each built around one half of an NE5532 dual op-amp. Each circuit uses that op-amp in a different configuration. The first circuit is a non-inverting pre-amp, the second is a unity-gain phase-inverter, and....
-
When Sl is off, Cl charges to within 0.5 V of the battery voltage through diode Dl and resistor R4. When Sl is closed, tbe anode of tbe PUT rises to the positive supply voltage. The PUT does not conduct, because battery voltage appears in series with tbe....
-
The converter has a 60-ms conversion consumes 460 pA of 1's. 5 V power supply and maintains an accuracy of 10 bits on a 15 ° C in the temperature range of 35 ° C. A pulse applied to convert the command line causes Q3, operating in reverse mode, the....
-
Here is a simple little HF TX. It may be modified for all the HF bands, but the details given are only for the 7MHz band. The basic transmitter uses two transistors; BC547 (as usual) and will deliver over 250mW of power. CW keying may be achieved by....
-
When a current of air hits tbe piezo element, a small signal is generated and is fed through Cl and Rl to inverting input pin 2 of one section of the LM324. That causes output pin 1 to increase. Resistor R3 is used to adjust the sensitivity of the....
-
A single transistor makes a simple phase shift oscillator. The output is a sine wave with distortion of about 104. The sine wave purity can be increased by putting a variable resistor (25 ohms) in the emitter lead of Q1 (x). The resistor is adjusted so the....
-
The heart of the circuit is ICZ, a 4046 micropower phase-locked loop (PLL). The incoming signals are fed to the PLL after being buffered by IC1a and its associated components. The frequency of the incoming signal is multiplied by either 90, 60, or 45,....
-
The 8051 series µCs offer idle and power-down modes, both of which you invoke by setting appropriate control bits from the code. For instance, a 5V, 12-MHz Atmel AT89C2051 consumes approximately 9 mA in active mode, 1.8 mA in idle mode, and only 12 µA in....
-
A single chip metal detecor with a range of a few inches. This is useful for decting nails or screws in walls and floors, or for locating buried mains cable...
-
The all-transistor T3SE works much like a conventional SE: like the Tritium, it fires when the charging current drops below the minimum and after the circuit triggers, positive feedback is used to latch the circuit, resetting at a fixed voltage on the main....
-
The 555 is a highly stable device for generating accurate time delays or oscillation. Aditional terminals are provided for triggering or resetting if desired. In the time delay (monostable) modeof operation the time is precisely controlled by one extrernal....
-
The second half controls the steering. The mechanical design is a 3 wheeled caddy with the ´single wheel´ actually a closely spaced pair of wheels which are driven by the main drive motor top provide motive power (this is the motor controlled by the first....
-
A four thyristor controlled bridge is used for operation in two quadrants of the torque-speed characteristics. In the trigger circuits the usual pulse transformers were replaced by self biased circuits which minimize gate power consumption and increase noise....
-
The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio picked up and
amplified by the electret microphone is fed into the audio amplifier stage built around the first transistor. Output
from the collector is fed into....
-
This project has two advantages over previous dice circuits. It produces a realistic readout as well as a `slow-down` feature.
These combine to make it one of our most popular games projects.
As can been seen in the photo, the 7 LEDs are positioned on the....
-
Upon opening your fridge door the photocell is exposed to light and the piggy oinks. Reverse engineered circuit diagram is of an early commercial design which uses an OP-AMP to make simulated pig sounds. Modern Fridge Pigs sound much better because they....
-
Building a headphone amplifier is like building a power amp - only the current demand is just a little bit lower (about a factor 100). Various designs can be found in the internet, and it is relatively easy to integrate the proposed crossfeed filter. I....
-
A Very Simple circuit and some Variations. Play with it.
All parts are cheap and should be easily obtained. None are very critical. ..
-
Many RS-485 and RS-422 networks require isolation for safety, noise reduction, or ground loop elimination. A conventional circuit is shown in Figure 1. Unfortunately, optocoupler isolation is slow, complicated, and unreliable. Although RTS does not require....
-
Traditionally, the reception quality of a digital receiver is expressed in terms of BER (bit-error rate). This figure is the proportion of received bit errors in a given period. Typically, you measure the BER in the lab by applying an RF signal, modulated by....
-
Some years ago, one of the fundamental electronic instruments was the laboratory curve tracer. A CRT display would sweep out terminal behavior (current versus voltage) from which you could derive mathematical models. Classic presentations of diodes,....
-
Originally, this circuit was used to sense a low-water level in a Christmas tree stand, but the circuit can be use..
-
Realistic flap and landing gear actuation.
This circuit slows the speed of a conventional proportional servo.
It regulates the time required for full servo rotation from 1 to 10 seconds without any reduction in the servo`s torque, and every servo....
-
The MiniBoard, a Motorola 68HC11 Robot Controller board designed by Fred G. Martin, also uses this driver. The day after, I then decided to prepare the page describing how to use C-52 EVB as a robot controller board. I asked my student for competition, build....
-
The capacitor charges until the PNP transistor (here shown as a 2N3906, but you could also use a BC327) receives base current through the Zener and turns on. Then the NPN transistor (here shown as a 2N3904, but you could also use a BC337) turns on and....
-
The Thermistor, or NTC (Negative Temperature Coefficient) of 10K, is a standard type. Most types will work. The one in the diagram is a 10K model made by Fenwal (#197-103LAG-A01). The resistance lowers as the surrounding temperature increases which affects....
-
The interface allows data to be saved on an ordinary tape recorder at a speed of 2400 bit/s. The serial stream of data Fig. 1 (A) is coded with a clock of 2400 Hz (B), by means of XOR gate IC 1/1. Logical "high" and "low" appear as shown in Fig. 2 (C). These....
-
Hot wire foam cutters are used by hobbyists of all stripes to contour Styrofoam into a vast array of shapes for a wide variety of uses. Model railroad builders shape foam into landscapes. RC plane builders shape foam into aircraft wings and fuselages.....
-
The UHF motion detector operates on the Doppler radar principle. Ql is an oscillator that creates a radiated signal. An..
-
This article describes an automated data collection system for analog-to-digital converters (ADCs). It discusses the advantages of automating data collection as well as a detailed description of the hardware and software. It goes on to explain the operation....
-
The LED predriver output pulses an external transistor which in turn, switches on the infrared light emitting diode at a very low duty cycle. The desired IR LED pulse period is determined by the value of the external timing resistor. The Smoke Sensitivity is....
-
This circuit uses a 556 to first generate a low frequency square wave, that is modulated to produce two alternate tones of about 400 and 500 Hz. Circuit generates warble alarm of European emergency vehicles. ..
-
This simple circuit can provide hours of enjoyment as you learn tunes, play duets or just make some really weird sounds by pushing all the buttons at once. You have probably seen this ciruit before, it is fairly common. I have seen it in several books. The....
-
This high-performance circuit first quickly starts (and holds) the charge at 2 amp, but as the voltage rises the current will consequently decrease. When the current falls below 150mA, the charger automatically switches to a lower 'Float' voltage to prevent....
-
This circuit shows a typical over/under-voltage fault monitor for a single supply. The upper trip points, controlling OUT 1, are centered on 5.5 V with 100 mY of hysteresis Wu = 5.55 V, "L = 5.45 V); and the lower trip points, controlling OUT 2, are....
-
You face a serious problem in using a slow ADC with a fast peak detector. The circuit in Figure 1 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 from Maxim....
-
This can be used to control entry on a Cat or Dog Door" NOTE: There may be some changes and improvements coming. However this circuit does work and you can build it as shown. The PCB Shown below is Available from me, or make it yourself. It Measures 2.75" by....
-
The monitor is a simple voltage comparator in which a car battery serves as the battery for operation. The input voltage to the comparator is set by adjustment potentiometer PI, which must be adjusted so that the green LED L2 is on when the alternator is....