Articles and news - 3

Simple log-scale audio meter
Simple log-scale audio meter
01.22.2024 Circuits

While refurbishing an ageing audio mixer, I decided that the level meters needed special attention...

Gated 555 astable hits ground running
Gated 555 astable hits the ground running
01.18.2024 Circuits

The classic and versatile 555 finds its way into many low to moderate frequency oscillator applications. Some of these require the ability to selectively gate oscillation on and off on demand and the 555’s RESET pin...

Temperature drift compensation audio power amplifiers
Temperature drift compensation for audio power amplifiers
01.16.2024 Articles

This article describes a technique to compensate the DC voltage drift in the output of a directly-coupled AB-Class audio power amplifier...

Adding one resistor improves anemometer analog
Adding one resistor improves anemometer analog linearity to better than ±0.5%
01.14.2024 Circuits

Awhile back I published a simple design idea for a thermal airspeed sensor based on a self-heated Darlington transistor pair. In the circuit, Q1 plays the role of self-heated sensor. Its VBE tempco converts temperature into voltage which is then offset and scaled by A2 to a 5 V span...

Proper function linearizes hot transistor anemometer
Proper function linearizes a hot transistor anemometer with less than 0.2% error
01.11.2024 Articles

A recent Design Idea presents a circuit to measure an airflow rate up to 2000 fpm using two transistors in a Darlington configuration. One transistor works as a self-heated thermal sensor and the other one compensates for ambient temperature variations. The circuit is smart and simple; however, the output voltage depends on the input flow rate in a very nonlinear fashion...

simple accurate efficient charge pump voltage
A simple, accurate, and efficient charge pump voltage inverter for $1 (in singles)
01.10.2024 Circuits

Keeping op-amp outputs “live” at and below zero volts, generating symmetrical output signals, and processing bipolar analog inputs, are all examples of design situations where a few milliamps of negative voltage rail can be a necessity...

Squashed triangles sines but teeth Part
Squashed triangles: sines, but with teeth? Part 2
01.09.2024 Circuits

Second test circuit I looked at several types of AGC circuits (strictly, Automatic Level Control)...

Squashed triangles sines but teeth Part
Squashed triangles: sines, but with teeth? Part 1
01.08.2024 Circuits

A while ago, I needed (or wanted) a pocket-sized audio sine-wave generator: simple, stable, repeatable, single-gang control pot, 9 V battery-powered. A “squashed tri-wave” approach looked appropriate...

Soft-start controller is gentle on loads
Soft-start controller is gentle on loads
01.02.2024 Circuits

The control circuit isenses a given load and automatically soft-starts the load by synchronously adjusting the power to that load. You can also manually adjust the power delivered to the load by controlling the phase angle of the line voltage across the load...

Linear switcher LED supplies combine overcome
Linear and switcher LED supplies combine, overcome disadvantages of each topology
12.28.2023 Circuits

To control their brightness, LEDs need a constant current; this can be done with a resistor placed in series with the LED string. Both the LED-string voltage and the supply voltage can vary, so a dedicated LED driver is a must to guarantee the current accuracy...

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