What is the the purpose of the 470 uF capacitor in this relay circuit?

Why there is no relay protection diode in this circuit?

The relay is used to toggle a voltage divider circuit.

relay dirve circuit

relay circuit

  • 1
    \$\begingroup\$ You haven’t said what the circuit is supposed to do. \$\endgroup\$
    – HandyHowie
    Commented Jul 10, 2020 at 7:55
  • \$\begingroup\$ Is it a latching relay ? Is it necessary that the contact be made and immediately broken ? \$\endgroup\$
    – AJN
    Commented Jul 10, 2020 at 7:55

1 Answer 1


The data sheet for that relay -


enter image description here

Shows that it is a latching relay. The capacitor will allow a pulse of current to the relay coil to activate the latch, but will then block the DC. Once latched no further current will be drawn.

Without more information as to what the circuit is supposed to be doing, it is not possibly to say why it is designed like this.


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