Converting a DCM Motor

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 available 35 (!) years ago. It is most likely that this motor is used due to financial constraints, because Märklin (as you probably guessed) […]

Test Beeper For Your Stereo

The test beeper generates a sinusoidal signal with a frequency of 1,000 Hz, a common test frequency for audio amplifiers. It consists of a classical Wien-Bridge oscillator (also known as a Wien-Robinson oscillator). The network that determines the frequency consists here of a series connection of a resistor and capacitor (R1/C1) and a parallel connection […]

4 order filter with a single IC

Filters with high orders are designed usually with 2 or more cascaded sections. This order 4 filter need only one OA IC , so we can achieve lower distorsions, lower intermodulation … Resistors values represent the load on the OA output, the maximum TL081 load is 2kΩ . R1-R4 build a 2.5kΩ impedance and so […]