paralleling relay coils

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In that case, here's another idea:-





\

+12~18V _ _ o o

| )|

1N4003 - )|

^_)|

|

|

|

100K ||-+

___ ||<- SiA408DJ

o--|___|--------+---||-+

| |

0/3.3V \| |

2N4401 |----+


| .-.

| | |

| | | 2.5R

| '-'

| |

+----- +

|

===

GND



It's even possible this is short-circuit resistant if you treat the

MOSFET well thermally.





Best regards,

Spehro Pefhany

--

"it's the network..." "The Journey is the reward"

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Looks to be easy way. I think it should be NPN.

 

[Spehro Pefhany]

Looks to be easy way. I think it should be NPN.

Right, thanks. The P/N is correct, symbol is wrong.

--sp

 

[Jasen Betts]

Circuit #2 produces neg voltage across coil on turn-off, bad choice.
Circuit #5 also potential transient over-voltage at turn-on due to diode capacitance.
Circuit #3 is really strange, hard to say but likely PNP is saturated so coil
-Vdiode at turn off is applied to output of 1117.

huh?
oh, you means the powersupply turn-on/off, not the relay?