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Help With Schematic Diagram

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PK:
Whilst some relays do have diodes inside, most do not.

As Phil said the schematic shows external diodes fitted across the coils to prevent them generating large reverse voltages when the switches are opened and the magnetic field in the relay collapses.
Without the diodes these large voltages would generate arcs across the switch contacts and wear them out.
PK

philf:
Hi Snub,

Just had a look at the data sheet. Even though they are in the same housing there are two independent relays. There doesn't look to be any diodes internally so you'd have to add them.

Phil.

BaronJ:
Hi Snub,

Some one has incorrectly used the symbol for a relay with built in diodes on the circuit diagram that you posted. After looking at the data sheet there are no diodes built into that relay, though they could have been.  You will have to add diodes yourself, any 1N4007 will work.  The 1N4007 is rated at 1000 volts, 1 amp.

You mention how they could incorporate diodes into a housing of that size along with all the other bits, well the die size for common diodes are only a couple of mm in area, and they wouldn't have any packaging around them to increase the size either.

snub:
Thanks for your help, all. Much appreciated.

mexican jon:
On a relay with such a small coil I wouldn't worry about adding diodes  :scratch: that is unless you are using something very delicate to fire the relay  :thumbup:

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