Patent GB-711570-A (GB)
Title: Improvements in capacitor testing apparatus
IPC: G01R31/01
Filed: 1951-12-28
Abstract: 711,570. Capacitance measurements. SOLAR MANUFACTURING CORPORATION Dec. 28, 1951, [April 26, 1951.] No. 30347/51 . Class 37. [Also in Group XXX] A capacitance testing apparatus comprises a capacitor feeding mechanism, an electrical circuit for testing the capacitance of these capacitors, and solenoid means for ejecting the capacitors from the feeding mechanism at. the end of the test, the feeding mechanism, testing circuit, and ejecting means being operated in a predetermined time sequence. Tubular capacitors are stored in a hopper 91, Fig. 2, which is periodically tilted about an axis 86 by an arm 70 reciprocated by a cam 56, Fig. 6, mounted on a shaft 32. When tilted upwards, the capacitors drop into a zig-zag channel in a shoot 142 which is then tilted about an axis I54 by an arm I20 actuated by a cam 50 reciprocated by a cam 30 on the shaft 32. The capacitors thus fall into a channel 172 and drop into slots in a disc 185 which is rotated on a shaft 200. Each capacitor is thus traversed past a plurality of testing points. The first test point comprises a pair of fingers which test the capacitor for short circuits. If there is a short circuit a solenoid is energized to eject the capacitor into a bin. The pair of fingers at the second test point connect the capacitor into an oscillator circuit. If the capacitor is of the right value so that oscillations of a particular frequency are produced a relay is actuated so that immediately after passing the test point the capacitor is ejected from the disc 185 into an appropriate bin. If the capacitor has a different value, the relay is not actuated and the capacitor is carried on to the next test point where it is engaged by another pair of fingers and connected in another oscillator circuit which is designed to eject the capacitor if it has a second value. This process is repeated e.g. six times, and if the capacitor has none of these six values it falls into a reject bin. Preferably all the oscillators are designed to produce the same frequency. One of the six circuits at the testing points is shown in Fig. 7. The output of the oscillator is limited at 300 and fed over two paths to reversed diodes 330, 340; one path includes a band-pass filter tuned to the frequency produced when the capacitor has the value appropriate to the testpoint. If the capacitor has this value, the output of the diode 330 exceeds that of the diode 340 and a normally conducting valve 400 is rendered non-conducting to change a second valve 405 from a non-conducting to a conducting condition thus actuating a relay 456 to change a capacitor 467 and create a temporary locking circuit for the relay 456, so that when the capacitor under test moves away from the fingers, the circuit reverts, but the relay 456 is not de-energized until the capacitor 467 has attained the potential of the power supply 455. This delay enables the capacitor under test to be completely disengaged from the test fingers, and the relay 456 releases to connect the capacitor 467 across a solenoid 465 and thus actuate its armature 500 to eject the capacitor that has been tested and found to be of the correct value. If the capacitor were not of the correct value, the relay 456 would not have been energized and the ejector would not have operated.