Relays in parallel

[Buffalo Tom]

Can I put 3 relays in parallel like this? OK with just one diode?



Its for a balanced stereo A/B selector. So left and right relays are 4pdt. The relay for the lamps is illumination for push button switches.

[bool]

I would change for beefier transistor; 2n2222 minimum. Most likely for a BD139 or similar.

[anotherjim]

+1^
I would fit a 1n400x series protection diode too. I never like to see small signal diodes in that role.

Could you drive both indicators from 1 pole of the Lamps relay and use the other pole for the pair of signal relay coils?

[PRR]

> Could you drive both indicators from 1 pole

And variations. The Lamp relay switches power, which can switch additional relays (to infinity, nearly, in some obsolete elevator controllers).

Ah, I think I misunderstood the lamp logic. OTOH, a double-throw switch is NATURAL for one-on one-off switching, leaving the other pole for flipping signal relays.

[Buffalo Tom]

Thanks for your replies! I changed to a beefier transistor and diode. Is this how you mean by drive both indicators from 1 pole of the lamps relay and use the other pole for the pair of signal relay coils? And is this version better than having 3 relays in parallel? One SPDT for the lamps and two 4PDT for the audio signal.

[anotherjim]

Yeh, that's what I meant - it doesn't need a beefier transistor, but there's no harm in that.
It's also to correct to include the protection diode for the relay switched coils because those master contacts can wear out prematurely from arcing caused by relay coil flyback.