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Every week I add here a little story about an existing circuit contradiction. I number and date these ideas consecutively as they have appeared in my mind; then, I arrange the contradictions systematically of circuit evolution - passive > transistor > op-amp etc.

In order to know more about the contradiction described, copy the circuit name from the table below, paste it in the subject field, add additional questions in the message body and e-mail me. Your e-mail will not be automatically answered; I will prepare every e-mail answer especially for you revealing the circuit contradiction> in a catchy and exciting manner. Thus you will get unusual and original explanations of the circuit operation that you have never seen before!

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September 27, 2004

Current-to-Voltage Converter The resistor in the circuit of a current-to-voltage converter has to have low resistance because of the input stage and it has to have high resistance because of the next stage. How do we solve the contradiction? Does it exist in case when the input stage is a constant current source?

October 04, 2004

Resistance-to-Voltage Converter The resistor in the circuit of a resistance-to-voltage converter has to have low resistance because of the input stage and it has to have high resistance because of the next stage. How do we solve the contradiction? Does it exist in case when the input stage is a constant current source?

October 11, 2004

Current-to-Voltage Capacitive Integrator The voltage drop across the capacitor in the circuit of a current-to-voltage capacitive integrator has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve the contradiction? Does it exist in case when the input stage is a constant current source?

October 18, 2004

Current-to-Voltage Inductive Differentiator

The voltage drop across the inductor in the circuit of a current-to-voltage inductive differentiator has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve the contradiction? Does it exist in case when the input stage is a constant current source?

October 25, 2004

Current-to-Voltage Logarithmic Converter

The voltage drop across the diode in the circuit of a current-to-voltage logarithmic converter has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve the contradiction? Does it exist in case when the input stage is a constant current source?

November 01, 2004

R2/R1 Voltage Divider

Imagine, we have to build a "perfect" voltage divider with ratio k = R2/R1 instead the "ordinary" voltage divider with a ratio k = R2/(R1+R2). For this purpose, we cascade an input voltage-to-current converter (resistor R1) and an output current-to-voltage converter (resistor R2). Only, the resistor R2 has to have low resistance because of the input converter and it has to have high resistance because of the output converter. How do we solve the contradiction?

November 08, 2004

Voltage-to-Voltage Capacitive Differentiator

In order to build a voltage-to-voltage capacitive differentiator, we cascade an input voltage-to-current differentiator (capacitor) and an output current-to-voltage converter (resistor). Only, the resistor has to have low resistance because of the input differentiator and it has to have high resistance because of the output converter. How do we solve the contradiction?

November 15, 2004

Voltage-to-Voltage Capacitive Integrator The voltage drop across the capacitor in the circuit of a voltage-to-voltage capacitive integrator has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve this contradiction?

November 22, 2004

Voltage-to-Voltage Inductive Differentiator

The voltage drop across the inductor in the circuit of a voltage-to-voltage inductive differentiator has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve this contradiction? Does it exist in case when the input stage is a constant current source?

November 29, 2004

Voltage-to-Voltage Inductive Integrator The voltage drop across the resistor in the circuit of a voltage-to-voltage inductive integrator has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve this contradiction?

December 06, 2004

Voltage-to-Voltage Logarithmic Converter

The voltage drop across the diode in the circuit of a voltage-to-voltage logarithmic converter has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve this contradiction? Does it exist in case when the input stage is a constant current source?

December 13, 2004

Voltage-to-Voltage Antilogarithmic Converter

The voltage drop across the resistor in the circuit of a voltage-to-voltage logarithmic converter has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve this contradiction? Does it exist in case when the input stage is a constant current source?

December 20, 2004

Ammeter

A movement coil has to have few winding in order to be low resistive (not to disturb the current measured) and it has to have many winding in order to be high sensitive. How do we solve the contradiction?

December 27, 2004

Base Resistor The base resistor in the circuit of a transistor switch has to have high resistance in order to obtain high input resistance; at the same time, the base resistor has to have low resistance in order to saturate the transistor. How do we solve the contradiction?

January 03, 2005

Collector Resistor The collector resistor in the circuit of a transistor switch has to have high resistance in order to saturate the transistor; at the same time, the collector resistor has to have low resistance in order to keep the high output level. How do we solve the contradiction?

January 10, 2005

Collector Resistor (Transistor Amplifier) The collector resistor in the circuit of a common-emitter amplifier has to have high resistance in order to obtain high amplification; at the same time, the collector resistor has to have low resistance in order to drive a big load enough. How do we solve the contradiction?

January 17, 2005

Emitter Resistor (DifferentialTransistor Amplifier) The emitter resistor in the circuit of a transistor differential amplifier has to have high resistance in order to obtain high CMRR; at the same time, it has to have low resistance in order to provide collector currents enough. How do we solve the contradiction?

February 07, 2005

Emitter Resistor in Transistor Current Source The emitter resistor in the circuit of a transistor current source has to have high resistance in order to obtain low error; at the same time, it has to have low resistance in order to provide high voltage compliance.

January 24, 2005

Bias Voltage Divider The bias voltage divider in the circuit of a common-emitter amplifier has to have high resistance in order not to load the input source; at the same time, it has to have low resistance in order to provide the base current needed. How do we solve the contradiction?

January 31, 2005

Blocking Capacitors The blocking capacitors in an AC amplifier has to be large enough in order to pass the AC current; at the same time, they have to be small enough in order not to "block" the amplifier. How do we solve the contradiction?

February 14, 2005

Input Resistor (R1) in Op-Amp Inverting Amplifier The input resistor R1 in the circuit of an op-amp inverting amplifier has to have high resistance in order not to disturb the input voltage source; at the same time, it has to have low resistance in order to obtain high gain. How do we solve the contradiction?

February 21, 2005

Output Resistor (R2) in Op-Amp Inverting Amplifier The output resistor R2 in the circuit of an op-amp inverting amplifier has to have extremely high resistance in order to obtain very high gain; at the same time, it has to have reasonable resistance. How do we solve the contradiction?

February 28, 2005

Leakage Input Resistor in Op-Amp Non-Inverting Amplifier The leakage input resistor in the circuit of an op-amp non-inverting amplifier has to have high resistance in order not to disturb the input voltage source; at the same time, it has to have low resistance in order to eliminate the influence of the op-amp input currents. How do we solve this contradiction?
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Last updated February 27, 2005