Flasher Circuit

摘要

1,190,168. Road traffic signals on vehicles; visible signalling-apparatus. WAGNER ELECTRIC CORP. 21 Aug., 1968 [21 Aug., 1967], No. 39900/68. Headings G4F and G4Q. [Also in Division H1] In a flasher circuit, including a power source 15 connected to a relay 14, a flasher 18 connected to the relay and a load having a non- linear resistance characteristic, such as lamp 30, connected to the flasher, the relay 15 is operative when a switch 28 is closed to shunt the flasher during an initial portion of the time period when the flasher contacts are closed. Normally the on time of a flasher 18 increases as the supply voltage 15 increases, however as shown the relay 14 is energized by the initial peak current required by the lamps when the switch 28 is closed. The relay contacts 20 close and shunt the flasher 18 until the peak load current has fallen to a more steady value (Fig. 2, not shown), when the contacts 20 open and the expansible wire of the flasher starts to be heated. After expansion of the wire the flasher interrupts the supply to the lamp 30 and the above operation is repeated. By suitably adjusting the contact gap 20 and the spring 22 the currents required to open and close the relay contacts 20 can be adjusted to values so as to compensate for supply voltage variations to maintain the ON time of the lamp 30 constant. The circuit may be used in a direction-indicating arrangement of a vehicle. Construction of flasher.-The flasher may be as disclosed in Specification 1,181,474 which has a snap-action spring blade 10 (Figs. 7 and 9) with a pull ribbon 24 under tension. When current is supplied to the ribbon 24 via fixed contact 32, movable contact 26 on the ribbon and the blade 10 and a fixed contact 34 the ribbon expands and allows the blade to obtain an equilibrium position (Fig. 8, not shown). The blade then snaps to the position shown in Fig. 9 where the contacts 26 and 32 are open and the blade 10 then rests on an adjustable stop 42. Also in this position the ribbon 24 passes through a slot (20, Fig. 4, not shown), in the blade and is prevented from going too far by a tongue (22) cut out from the slot (20) and by the stop 42. Adjustment of the stop 42 controls the rate of flash. The blade may be of steel.