Absolute-Value Meter With Polarity Detector

Posted on Feb 7, 2014

This circuit breaks an input voltage signal down into its components: (1) the absolute value and (2) the polarity or sign` (+ or ). It will handle direct input voltages as well as alternating voltages up to several kHz. With a supply voltage of ±9 V, the input level should remain below ±6V. The circuit consists of two sections, each having it

Absolute-Value Meter With Polarity Detector

Click here to download the full size of the above Circuit.

s own function. Operational amplifiers IC1a and IC1b form a full-wave rectifier, its output terminal supplying the absolute value of the input signal, while operational amplifiers IC1c and IC1d examine the polarity of the input voltage. For negative input voltages, the output of IC1a goes high. Consequently D2 is reverse-biased so that IC1a has no effect on the rest of the circuit. IC1b then acts as an inverter because its amplification is ( R5/R3) or 1. Thus, the output voltage is positive. For positive input voltages, D2 conducts and the amplification of IC1a is -1. The output voltage is then determined by the sum of currents that flow through R3 and R4. Taking into account the polarities and the value of all resistors, the overall amplification becomes This means that the value of the output voltage at the output terminal is the same as the input voltage, but the polarity is always positive. The accuracy of the rectification process is determined by the accuracy of resistors R1-R4; close-tolerance (1%) types are recommended. At low input voltages (smaller than 20 mV), the input offset voltage of the operational amplifiers may introduce significant errors. If this is the case, use individual operational amplifiers instead of an array of four (TL061, TLC271, AD548, . ), because they have pins for offset voltage compensation. Alternatively, use an operational amplifier with a low offset voltage like the OP07. In the...

Visit page

Leave Comment

characters left:

Related Circuits

Arduino GoPro Hero2 Control

I wanted to do some time lapse photography where the camera would take 1 capture every 20 minutes or so of a race car chassis fabrication project. After looking around on the web, I decided the...

Pattern generator

A pattern generator is a very useful instrument for the correct alignment of the timing circuits of a television set. The circuit we propose you to build, is a «bar generator» that will produce...

TYPICAL TRANSISTOR CIRCUIT

This is a silicon transistor circuit showing typical voltage values. When the forward base/emitter voltage is 0.6 to 0.7 V, the transistor is silicon. Germanium transistors will have a forward...

learning Arduino programming

The circuit consist of 10 k and 470 k resistors. Also one potentiometer resistor and led was used. This circuit is used for learning Arduino programming later in class.

Fast Optical Recording Circuit

This document presents technical details, hardware and software of a complete imaging system which uses a fast CCD sensor and a 41 Msample/s A/D converter to acquire full-frame 12 bit/pixel...

Wien bridge oscillator circuit

In this laboratory experiment, we need to design the frequency determining network for a 1k Hz sinusoidal oscillator. Therefore, we should set: Capacitance = 100nF Resistance = 1520 ohm

1996 Suzuki Esteem Cooling Fan Circuit Diagram

The 1996 Suzuki Esteem Cooling Fan system consists of control relay for: radiator fan (located in relay box), air conditioning fan motor, radiator fan motor, condenser fan motor, junction box, fuse...

Finding an Electrical Short

Over time, many things can cause electrical problems with your Mustang. Components will get old and worn or a wire can rub against something and expose the wire to metal. I have seen where a body...

New Circuits

Zero consumption Anti-theft High power Code Switch for E-Bike Batteries

This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
Ultrasonic distance finder circuit

The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Simple Metal detector circuit with CD4030

Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Fully automatic watering circuit for flower pots

Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
Simple deep searching metal detector circuit

The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
Sub-Harmonic Bass Converter for Electric Guitars

The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
Echo Depth Sounding Sonar for Boats

In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
100W HiFi Audio Amplifier Circuit

This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
Plant-Pot Water Level Indicator Circuit

A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....