The simplest way to make an adjustable constant current source is to use a voltage regulator in a suitable configuration: an example of what is needed is given in the LM317 datasheet. Howeve... Read more
When testing circuits and fault finding there is often a need to inject a defined DC voltage level at some point on the circuit. It may, for example, be necessary to apply a logic level on t... Read more
The circuit described here provides monitoring of the charge status of a battery by the continuous measurement of charge and discharge currents. The battery current is integrated over time (... Read more
This design resulted from the need for a partial replacement of the well-known 8038 chip, which is no longer in production and therefore hardly obtainable. An existing design for driving an... Read more
Creating a current source (as opposed to current sink) for driving a grounded load can be a bit awkward. Admittedly the suggested circuit cheats a little in that the load is tied to virtual... Read more
Most guitar pedals obtain a high input impedance simply by using a large resistor at the input of the first opamp, but this generates a good deal of noise due to the input bias current. The... Read more
The compact circuit presented here is perfect for receiving the signals from pulsed fixed frequency transmitters. Chest straps from several well-known brands (Polar, Huger, Kettler, Crane, O... Read more
The most recent PC motherboards provide four-pin connectors for cooling fans, especially for the CPU fan. The older three pin fans are controlled by varying their DC voltage. The fourth pin... Read more
The new range of low-noise, highspeed, and low-distortion BiMOS opamps from Texas Instruments, type TLC070 to TLC075, is intended for use in instrumentation, audio, and automotive applicatio... Read more
With the well-known TDA2030V integrated power amplifier in the Pentawatt package, it is easy to ‘activate’ a PC loudspeaker or upgrade the quality of an inexpensive active loudspeaker. The T... Read more
