I'm using teledyne relay 420 in our project. Can anyone help me out with its pin functions and connections?
The datasheet is here http://www.teledynerelays.com/pdf/electromechanical/420422.pdf
In the schematic diagram for 420 relay shown in the datasheet there is a point where ends of the coil are connected. What is that small circle? There isn't any pin on the i.c that comes out from that point. There are only 8 pins.
Best Answer
Take a look at the last page of the data sheet and you'll see that that's a case ground. It is a pin, but it's part of the header and the minus end of each coil is connected to it internally.
EDIT:
If you start with the tab and count clockwise looking at the bottom of the can, the ground pin will be between pins 4 and 5. From the data sheet it appears that it's not a lead, it's only a pin and it's only 0.01" high, so that may be a problem for you if you're expecting a lead there. In any case, you'll need to use the case as as your ground connection for the coils, with pin 4 being the other end of COIL A, and pin 8 being the other end of COIL B. If you need ground leads for the relay coils, then you might want to order 422s.
Note, from the data sheet: "SCHEMATICS ARE VIEWED FROM TERMINALS CONTACTS SHOWN IN POSITION RESULTING WHEN COIL A LAST ENERGIZED".
Note also that when coil "B" is activated, BOTH sets of contacts will change over and latch from how they're shown on the data sheet, and then change back and latch when coil "A" is later activated.