In this paper, universal motor speed control system with a PWM AC chopper is introduced. Operation principles of the control system, which is realized with a microcontroller, are presented. Mathematical model of the universal motor and PWM AC chopper is derived and the behavior of the system is studied by simulation. Mains power factor, motor speed, and current are analyzed for different load c...

In this paper, a chopper stabilized fully differential CMOS pre-amplifier circuit is presented. The proposed circuit is designed for sub-atto Farad capacitive CMOS MEMS sensing applications. Chopper stabilization technique is employed to minimize flicker (1/f) noise and offsets in the circuit. The proposed circuit is designed using MIMOS 0.35 μm AMS CMOS 3.3 V technology and simulation results ...

High repetition rate (HRR) lasers are essential in multiphoton microscopy for satisfactory signal to noise at low average powers. However, HRR lasers generate thermal distortions in samples even with the slightest single photon absorption. Using an optical chopper with HRR lasers ("blanking") we demonstrate a femtosecond z-scan setup that effectively eliminates thermal as well as small linear a...

The recent development of high power DC/DC converters (more commonly know as Chopper Rectifiers) allows customers the option to keep older rectifier transformers and refurbished systems if reconfiguring or installing new cell line loads. Normally, new cell line impedances would require the replacement of transformer/rectifier equipment. This paper is intended to describe how one can change the ...

Here an analytical calculation for the transmission probability of neutrons travelling through a revolving slit is being presented. For the first time, two effects have been taken into account in the same approach, that is on the one hand the fact that the neutron beam might be divergent and, on the other hand, that neutrons from a continuous source can arrive at different times at the chopper....

In general, the choice between boxcar averaging (gated integration) and lock-in detection (phase sensitive detection) is based on the time behavior of the signal. If the signal is fixed in frequency and has a 50 % duty cycle, lock-in detection is best suited. This type of experiment commonly uses an optical chopper to modulate the signal at some low frequency. Signal photons occur at random tim...

This paper discusses a single-phase three-level current source inverter (CSI) driven by a single gate-drive power supply in both chopper and inverter, and its feasibility on grid connected photovoltaic system application. Using this new topology, the complexity of the chopper and inverter circuitry is dramatically reduced by using single gate-drive power supply for all power switches. The circu...

Since the introduction of monolithic IC amplifiers there has been a continual improvement in DC accuracy. Bias currents have been decreased by 5 orders of magnitude over the past 5 years. Low offset voltage drift is also necessary in a high accuracy circuits. This is evidenced by the popularity of low drift amplifier types as well as the requests for selected low-drift op amps. However, until n...

In the spring of 1856, I met Mr. Christy accidentally in an omnibus at Havana. He had been in Cuba for some months, leading an adventurous life… and visiting all sorts of people from whom information was to be had.