ENIAC i n i. k or n i. Electronic Numerical Integrator and Computer was amongst the earliest electronic generalpurpose computers made. BibMe Free Bibliography Citation Maker MLA, APA, Chicago, Harvard. Encyclopedia-of-Analytical-Science-Second-Edition1.jpg' alt='Encyclopedia Of Electronic 1000 Circuits Pdf' title='Encyclopedia Of Electronic 1000 Circuits Pdf' />Pulse transformer Encyclopedia MagneticaPulse transformer for some applications also gate transformer. Pulse transformers can be used for signal transmission galvanic isolation, low power control circuits, as well as the main components in high power switched mode power supplies. Typical pulse transformers 78 used in low power electronic circuits. S. Zurek, E. Magnetica, CC BY 3. Low power pulse transformers are used for controlling switching elements like power semiconductors transistors, thyristors, triacs, etc. In such applications the name gate drive transformer is also used. The distinction is based mostly on the actual purpose of the transformer, where the transformer is used to directly drive a transistor gate it is referred to as a gate drive transformer, if used only as a means of transmitting rectangular voltage signals then as a pulse transformer. However, in a general sense a pulse transformer is any transformer capable of transmitting voltage pulses often rectangular with adequate signal fidelity. Requirements like high permeability core, low leakage inductance, low inter winding capacitance etc. Therefore, extremely high power transformers rating MW or even TW can be referred to as pulse transformers. As with most transformers, pulse transformers can utilise several functionalities simultaneously pulse fidelity, voltage level transformation, impedance matching, galvanic isolation, DC isolation, etc. Technical requirements. Technical requirements are always specific to a given application hence it is not possible to have a universal configuration. However, there are features which are favourable for most implementations, and some of them are given as examples below. Galvanic isolation. A pulse transformer usually has galvanic isolation between its windings. This allows for the primary driving circuit to operate at a different electric potential from the secondary driven circuit. The isolation can be very high, e. V for small electronic transformers. This is especially true for very high power applications in which the output voltage can reach 2. V. 1. 7. The galvanic isolation also allows meeting safety requirements if one part of the circuit is unsafe to touch, due to the danger of higher voltage, even if for a brief period of time e. Pulse transformation. For a gate driving applications usually a rectangular voltage pulse with fast rising and falling edges is required. The frequency bandwidth must be high enough for a given application, so that the delay in signal transmission is acceptably small and there are no severe distortions of the signal. The frequency bandwidth and signal fidelity are dictated mostly by the non ideal and parasitic parameters of the transformer inter winding capacitance, self capacitance of each winding, equivalent resistance, etc. Combination of these parameters can cause a number of effects on the transformed pulse overshoot, droop, back swing, rise time and fall time, which appear as unwanted signal distortions. A good quality pulse transformer should have low leakage inductance and distributed capacitance as well as high open circuit inductance. The transformed pulse will be only a poorer copy of the input pulse. So the if the driving circuit produces a non ideal pulse then the pulse shape will suffer from additional distortions. Windings and turns ratio. Update Formula To Include Cells Automatically Reset. In most low power or applications the turns ratio is around unity 1 1 or similar like 1 2. Only when the level of signal must be changed to a different voltage then a significantly different turns ratio will be used, as it is the case for most transformers in forward converters low or high power. Pulse transformer can have more than two windings, which can be used for instance to drive several transistors simultaneously, so that any phase shifts or delays between signals are minimised. Typical configurations of low power pulse transformers. S. Zurek, E. Magnetica, CC BY 3. Simplified example with a two winding 1 1 pulse transformer driving a gate of a MOSFET T. S. Zurek, E. Magnetica, CC BY 3. Simplified example with a three winding 1 1 1 pulse transformer driving gates of thyristors T1 and T2. S. Zurek, E. Magnetica, CC BY 3. Multi winding pulse transformer wound on a toroidal core, for a specialised application. S. Zurek, E. Magnetica, CC BY 3. Saturation. A pulse transformer can operate correctly only when the magnetic saturation is avoided. For this reason most electronic pulse transformers have a rating volt second product given in their data sheets. This value indicates what amount of energy can be safely applied to the primary winding before the saturation occurs. For small transformers these values can be specified as e. Vs2. 2, so a 1. V pulse could be applied for 2. After the pulse is applied the circuit must provide the transformer with a means of resetting the flux, otherwise saturation might occur after repeated pulsing due to DC offset or flux walking. This can be achieved for example by AC coupling through a series capacitor. How To Open Htc Sms Backup File On Pc. In some applications presence of strong magnetic field might cause problems for operation of pulse transformers with high permeability cores. The core could saturate which might lead to partial or full loss of signal fidelity. In order to avoid such problems some magnetic shielding might be required. Leakage inductance and parasitic capacitance. High power pulse transformer with conically shaped windings for minimising parasitic capacitance 2. Dominik Bortis, Copyrights. Leakage inductance is an unwanted parameter and its value should be as low as possible. This is achieved firstly by using high permeability magnetic core. As it is for other transformers, the type of material depends on the required frequency bandwidth and other operating parametres. Some applications use soft ferrite, mumetal, 2. Reduction of leakage inductance is also achieved by tightly wound coils, e. Leakage inductance of typical electronic pulse transformers is less than 1 of the total primary inductance. The leakage inductance stores energy which must be removed after which driving pulse. This can worsen the energy efficiency but also increase time delay in the gate driving applications. As in any transformer, minimising leakage inductance by winding primary and secondary winding close to each other usually leads to increased inter winding capacitance, which is also an unwanted parameter. On the other hand, higher insulation between the windings might require larger distance between them and this lowers the parasitic capacitance, but increases the leakage inductance. Although not always specifically referred to as pulse transformers there are devices used for the purpose of pulse transmission. Such devices might not have a magnetic core at all, so that the leakage inductance will be proportionally much greater. However, their capability is sufficient for achieving the pulse transformation as required in a given application. Therefore, because of the very function they are used for they can also be referred to as pulse transformers. Pulse transformers are build in a wide range of power ratings, from on chip transformers built into integrated circuits. As with other transformers, the cost of pulse transformers is related to their power rating.