Silicon Rectifier Characteristics
A—Reverse direction of silicon rectifier is characterized by extremely high resistance up to point of avalanche voltage.
B—Threshold voltage of silicon cell is about 0.6 volt. Once device starts conducting the current increases exponentially with small increments of voltage, then nearly linearly on a very steep slope.
® HIGH CURRENT SUPPLY © 900 WATT HIGH VOLTAGE SUPPLY
Figure 16 SEMI-CONDUCTOR POWER SUPPLIES
® HIGH CURRENT SUPPLY © 900 WATT HIGH VOLTAGE SUPPLY
Figure 16 SEMI-CONDUCTOR POWER SUPPLIES
A—Voltage quadruplet circuit. If point "A" is taken as ground instead of point "B," supply will deliver
530 volts at 150 ma. from 115 volt a-c line. Supply is "hot" to line. B—Voltage triplet delivering 325 volts at 450 ma. Supply is "hot" to line.
C—900 watt supply for sideband service may be made from two voltage quadruplets working in series from inexpensive "distribution-type" transformer. Supply features good dynamic voltage regulation.
PARTS LIST:
Di—Sarkes Tarzian Model 150 selenium cell or Model M-500 silicon cell. Di—Sarkes Tarzian Model 500 selenium cell or Model M-500 silicon cell.
Ti—Power distribution transformer, used backwards. 230/460 primary, 115/230 secondary, 0.75 KVA. Chicago PCB-24750.
ments, delivering 100 watts at various voltages to run both the mobile transmitter and receiver. The input power required by the supply is almost directly proportional to the output power drain, and only a small amount of power is wasted to actuate the vibrator reeds.
The large demand for efficient and powerful mobile radio equipment has led to the development of new heavy-duty, vibrator-type power supply components; these are used to advantage in this unique design.
The Split-Reed The new split-reed dud-inter-Vibrator rupter vibrator overcomes the power capacity limitations of the older type vibrators. In addition, this vibrator permits the design of power supplies requiring no component changes for operation from either the 6- or 12-volt d.c. power systems with which most automobiles are equipped.
Until recently, the majority of vibrator supplies have been designed around the synchon-ous type vibrator. A simplified diagram of such a vibrator is shown in figure 18A. One set of vibrator contacts switches the battery current alternately through two opposed primary windings of a transformer, thus inducing a square-wave a.c. voltage in the secondary. This a.c. secondary voltage is then rectified by a second set of contacts on the vibrator armature. The limitations of this circuit are low power handling capacity and the need to use a different number of turns on the transformer primary when the battery voltage is changed from six to twelve volts.
In the split-reed vibrator (figure 18B), two sets of double-throw contacts are electrically isolated from each other. Each set has much greater current carrying capacity than the synchronous vibrator. However, a power transformer having two center-tapped primary windings is required. One set of contacts switches the d.c. power alternately between halves of one primary winding, and the other set simultaneously switches the other winding. Therefore, the primaries can be connected in parallel for 6-volt operation, or in series for 12-volt operation. No wiring changes are needed in the supply if the battery is properly connected to the power input terminals.
The Selenium A selenium rectifier system Rectifier System is employed in this supply.
Since the vibrator contacts open and close abruptly, the periodically in
Figure 17 100 WATT MOBILE POWER SUPPLY
This high efficiency mobile supply features 6 or 12 volt input, and will completely power both the mobile transmitter and receiver. 450, 300, and 240 volts are available. At right is control box for complete mobile system. Overall size of supply is only 6"x6"x6".
Figure 17 100 WATT MOBILE POWER SUPPLY
This high efficiency mobile supply features 6 or 12 volt input, and will completely power both the mobile transmitter and receiver. 450, 300, and 240 volts are available. At right is control box for complete mobile system. Overall size of supply is only 6"x6"x6".
terrupted voltage impressed on the transformer primary has practically a square waveform. The secondary voltage also has nearly a square waveform as a result and thus the peak voltage on the rectifiers is only slightly higher than the average voltage of the waveform. This means that the rectifiers in a vibrator-type power supply can be operated on a square wave voltage close to their maximum peak inverse voltage rating, instead of considerably below this rating, as when a sine wave a.c. voltage is applied to them.
Power Supply This power supply has three Circuit high voltage sections as shown in figure 19. The 250 volt receiver supply is shown in figure 19A, the 300 volt low voltage transmitter supply in figure 19B, and the 450 volt high voltage transmitter supply is shown in figure 19C.
Note that each rectifier has two sections. The part numbers correspond to the markings shown in the complete schematic of figure 20. In the 250 volt circuit, the full transformer secondary voltage is applied to a full wave rectifier consisting of half of rectifiers SRi and SRa. These two rectifiers form a common portion of all three rectifier circuits. The junction of the two rectifiers is grounded and the positive 250 volt output is taken from the center-tap transformer lead. This is the opposite of the usual full wave rectifier circuit.
The 300 volt d.c. output is obtained from a bridge rectifier circuit (figure 19B) consisting of one-half of SRi and SR2 in the ground legs, plus SR3 in the two bridge legs from which the positive voltage is obtained.
Another bridge rectifier circuit is employed for the 450 volt d.c. output, again with the
- vibrator transformer
split reed vibrator dual primary vibrator transformer split reed vibrator dual primary vibrator transformer
6 volt connections
6 volt connections
Figure 18
Post a comment