A device for providing an orderly shut-down of a system of interconnected traffic lights upon loss of its primary electrical power is disclosed. A device for permitting consistent reapplication of power to a line conditioner having a ferroresonant transformer is also disclosed. Further, a battery charger for charging a battery system including a plurality of battery cells coupled in series is disclosed. Additionally, a device for determining proper operation of a power transistor by monitoring i...

A gating system for use with a frequency discriminator which will provide a positive indication of whether or not two input signals are the same frequency or, if they are not the same frequency, which one is the higher. The apparatus is for use with a frequency detector providing logic "1" and logic "0" outputs indicative of the highest frequency and providing an alternating output when the two frequencies are identical. The output of the frequency discriminator is utilized to steer flip-flops t...

A phase lock loop employs a frequency discriminator having a relatively slow response to pull a voltage controlled oscillator into frequency lock with an input signal. After frequency lock the output of the frequency discriminator is nulled and a phase detector becomes effective to maintain phase lock. The frequency discriminator utilizes an operational amplifier to which both the input and oscillator signals are capacitively coupled through respective oppositely poled diode gates. A feedback ca...

Circuitry for filtering a distinct variable spectral component includes a band-rejection filter formed by a summing amplifier with a feedback loop and a bandpass-filter connected to one of its inputs. The summing amplifier is connected to form the difference between the unfiltered spectrum at one of its inputs and the spectrum component to be suppressed at another of its inputs. The summing amplifier delivers the filtered signal spectrum at its output. A control circuit locks the common center f...

A variable frequency three-phase square wave signal is synchronized to a three-phase reference frequency signal at a substantially zero degree phase relation. Synchronization is accomplished in but a few cycles by comparing each component of the two signals to be compared and also comparing both positive and negative going half cycles of each component. Six phase error magnitude pulses are generated for each cycle and identified according to phase error sense to provide an output error signal ha...

A circuit is provided for producing a control voltage depending on a frequency and/or phase difference between a first and a second periodic signal. The periodic signals are fed to trigger circuits to provide trigger signals. An inhibiting time interval generator receives the trigger signals and produces inhibiting signals. The trigger signals are the inhibiting signals are fed to an inhibiting circuit which inhibits passage of trigger signals depending on the passage of recently passed trigger ...

An arrangement for determining the phase position between two signals includes a circuit containing a gate with two inputs for the signals and an output for a first output signal which is dependent on the phase position between the input signals. A flip-flop has an input for one of the input signals and a second input for the first output signal. The second input of the flip-flop contains a time-delay circuit for the first output signal. Two similar circuits can be used.

A method for manufacturing a pair of electrodes comprises fabricating a first electrode with a substantially flat surface and placing a sacrificial layer over a surface of the first electrode, wherein the sacrificial layer comprises a first material. A second material is placed over the sacrificial layer, wherein the second material comprises a material that is suitable for use as a second electrode. The sacrificial layer is removed with an etchant, wherein the etchant chemically reacts with the...

An insulated gate bipolar transistor (IGBT) and a method for manufacturing the same is provided. This method is capable of preventing a latch-up and improving a short current characteristic. In the IGBT, a second conductive type semiconductor layer is formed over a semiconductor substrate. A first conductive type well is then formed beneath the surface of the semiconductor layer, and a second conductive type source region doped with a high concentration is formed in the well. Also, a gate electr...

A method for manufacturing a pair of electrodes comprises fabricating a first electrode with a substantially flat surface and placing a sacrificial layer over a surface of the first electrode, wherein the sacrificial layer comprises a first material. A second material is placed over the sacrificial layer, wherein the second material comprises a material that is suitable for use as a second electrode. The sacrificial layer is removed with an etchant, wherein the etchant chemically reacts with the...