Phantastron

Phantastron One of the original types of signal generators of a complex form is phantastron. It belongs to the class of relaxation oscillators and can be made both on tubes and semiconductor devices. The output signal of the phantastron has an asymmetric sawtooth configuration of equal length but different frequencies. Phantastron with a large difference of changing voltage (tens and hundreds of E) is performed on the electronic tubes (usually pentodes and pentagrids), with a smaller voltage drop -- on bipolar or monopolar field-effect transistors. The full cycle of phantastron work is divided into stages of waiting (rest), starting, operating and recovery. The duration of the working stage of the phantastron (i.e., the duration of the generated pulses), depending on the parameters of the scheme, lies within the range of several microseconds to several tens of seconds. It can be adjusted smoothly -- by a potentiometer, and step-wise -- by a capacitor. Phantastrons are traditionally used in the circuits of precise control of the time delay, as a sawtooth voltage generator, as a generator of rectangular pulses of long duration in radio devices. In oscilloscopes the phantastron is often used in the sweep circuit. One of the modern variants of the phantastron use is the circuit of the electronic drum constructed on its basis. Herewith, in modern musical electronics the use of phantastron tube circuits is as wide spread as the use of semiconductor devices.