### Lapping machine of tension

A lapping machine of tension is an electrical circuit making it possible to obtain twice a output voltage equal to the tension of entry. The lapping machines of tension are thus multipliers of tension with for factor two. For that of the interruptory condensers and elements are used.
The simplest circuits are rectifiers having for a tension of alternate entry (AC) and exit a continuous tension (cd.) doubled. The commutating elements are diodes and are thus commutated naturally by the alternating voltage. Circuits DC ⁄ DC need commutating elements commandables, for example a transistor, in order to carry out the doubling of the tension.
Often the multipliers of tension of a higher nature are right extensions of the circuits lapping machine of tension with more stages. One speaks about setting in cascade. In this case, the comprehension of the associated lapping machine of tension is simpler than that of the whole of the assembly.
Circuit of Villard
The circuit of Villard is only made up of one condenser and a diode. It has as advantages its great simplicity and its low level of harmonics. It functions like a circuit clamp. The condenser is in charge on during alternation (half-period) negative to the maximum amplitude of the alternating voltage (Vpk). The output voltage is equal to the alternating voltage of entry to which the constant tension of the condenser is added. The circuit makes pass the component continues signal of zero in Vpk, its minimum becomes zero volt, by neglecting the tension of threshold of the diode, the maximum output voltage thus becomes 2*Vpk. The output voltage is certainly continuous, it strongly oscillates at the rate/rhythm of the alternating voltage of entry. To avoid these oscillations, the circuit should be made much more complex. It is the circuit generally employed, with that with reversed diode, to feed in negative tension the magnetron of a furnace microwaves.
Circuit of Greinacher
The assembly of Greinacher is definitely better than that of Villard for a very limited overcost. The harmonics are normally very weak, zero for the open circuit, dependant on the resistance of the load and the value of the capacities if not. Coarsely, it is about a circuit of Villard associated with a detector with peak. This last element makes it possible to limit the oscillations in the output voltage.
This circuit was invented in 1913 by Heinrich Greinacher in order to enable him to supply its ionometer between 200 and 300 V thanks to the network 110 V of the town of Zurich.
It puts then its circuit cascades about it in 1920 to carry out a more powerful multiplier of tension. The assembly cascades of Greinacher by error is sometimes named assembly cascades of Villard. In 1932, John Cockcroft and Ernest Walton redĂ©couvrent the assembly in an independent way and use it for their particle accelerator, the assembly is sometimes thus called Cockcroft-Walton generator.
By assembling two assemblies of Greinacher in an opposed way, one obtains a quadruplor of tension. As in the case of a bridge, it is not possible to put at the ground at the same time the entries and the exits of this assembly.
Circuit of Delon
The circuit of Delon is an electric bridge being used to double the tension. This assembly was very current in the construction of cathode tube televisions, where it was used to provide the food very high voltage. Indeed, an electric transformer is at the same time expensive and dangerous within the framework of a use tension of 5 Kv domesticates beyond. Televisions black and white needed 10 Kv, that colors moreover, it was thus necessary to find another solution. A lapping machine of tension was installed after rolling up high voltage of the transformer or on the transformer fly-back.
The circuit is carried out thanks to two detecting circuits of peak and functions in a way similar to the assembly of Greinacher. Each half-circuit functions during an alternation. The output voltage is equal to twice the amplitude of the tension of entry, in other words equal to the amplitude peak with peak.
Circuit with commutated condensers
A chopper can be combined with the circuit of Villard. Thus, a continuous tension can be made alternate, doubled then rectified. The circuit is then more powerful if the switches are commutated simultaneously by an external clock. This type of gating circuit the name of circuit with commutated condensers. This approach is particularly useful in the case of applications with a battery of weak tension and where the integrated circuits require a tension higher than that of the battery. A clock being generally present in the integrated circuits, the overcost of such an assembly is often null.
The figure presents one of the assemblies to commutated condensers simplest. The two condensers are charged simultaneously with the same tension. The food is then stopped and the condensers connected in series. The output voltage east taken at the boundaries of the two series condensers, it is thus twice higher than the initial tension. Many elements can be used in order to carry out commutation, in practice however them.
Circuit lapping machine of tension out of pump of load
The condenser CP is initially charged with the tension with entry. The switches are commutated and the first series condenser with the source start to twice charge the condenser with C0 exit to the tension of entry. The total loading of the C0 condenser can take several periods, but in permanent mode the loads and discharges of CP must be with balance. They result in light oscillations. If the frequency is high, these oscillations are weaker and easier to filter. In the integrated circuits, the frequency of maximum clock is typically about a few hundred Khz.