This simple LED tester consists of a current source with a potentiometer that can be used to adjust the current. The current source is implemented using a type TL081 opamp. The output curren... Read more
To detect the arrival of a particular range of voltage(s) from the swing of an input signal, this circuit is used. Two Op-Amps in comparator mode are used in this circuit. A lower comparator... Read more
In this circuit, Op-Amp operates in a closed loop. Input is applied to Non-Inverting terminal and output is fed-back to the Inverting terminal as a voltage shunt feed-back. The polarity of... Read more
The difference of the voltage between V+ and V- is amplified in this circuit. It is similar to the comparator mode, and in addition the Op-Amp is operated in a closed loop, making it possib... Read more
In this circuit, Op-Amp operates in the closed loop. Input is applied to the Inverting terminal and output is fed-back to the inverting terminal as voltage shunt feed-back. The polarity of t... Read more
We recently bought a train set made by a renowned company and just couldn’t resist looking inside the locomotive. Although it did have an electronic decoder, the DCM motor was already availa... Read more
A Zener diode is the simplest known type of voltage limiter (Figure 1) As soon as the voltage exceeds the rated voltage of the Zener diode, a current can flow through the diode to limit the... Read more
Ever wanted to build a positioning encoder? Here’s one and you do not even need any sensors. The circuit uses an LED as a light emitter and another LED as a light receiver. This is possible... Read more
This is a tried and trusted design for the protection against overvoltages that can be configured for your own needs. The circuit can also be used to detect under voltages; in that case, the... Read more
This circuit should be considered as more of an experimental circuit for AM demodulation, than as a practical application. In the associated ‘AM modulator’ we have raised the problems caused... Read more
