If you want to try using a flip flop, here's one way. It's more involved though than using a toggle switch and passive circuit.
The button is an ordinary momentary NO push button. R3/R6 set the pulse duration.
You can add LED indicators in parallel with each coil to indicated status (as long as it doesn't need to be fail safe).

The CD4013 comes with two FF in a package, so I used one to square up the PB input signal.

View attachment 227964

 

Yes. Across each relay coil. It doesn't matter if the load is energized or not.
But another thing to consider is the possible affect on nearby components.
Its better just to add them and eliminate possible emf affects.

In this case i will be needing 2 diodes for one relay. For set and reset coil right?

 

5V double coil latching has 12.5Ω coils - that's 400mA!
To get a 100mS time constant with that coil would require capacitors of at least 8200uF

 

In this case i will be needing 2 diodes for one relay. For set and reset coil right?

Correct... and the diodes must be reverse biased.

 

5V double coil latching has 12.5Ω coils - that's 400mA!
To get a 100mS time constant with that coil would require capacitors of at least 8200uF

Told you I don't know the math. Albert does. My test was with a 12V coil with 273Ω coil resistance. The 470µF cap I tested with held for about a quarter second. 200mS guesstimate.

 

In this case i will be needing 2 diodes for one relay. For set and reset coil right?

Yes.

 

5V double coil latching has 12.5Ω coils - that's 400mA!
To get a 100mS time constant with that coil would require capacitors of at least 8200uF

Yes....like I mentioned back in post #50.
Different relay, same result...

 

Correct... and the diodes must be reverse biased.

will this diode do the job ?
https://eu.mouser.com/ProductDetail/ON-Semiconductor/1N4001RLG/?qs=y2kkmE52mdNtNRrsA1ylQg==
The wiring would be to connect negative terminal to common positive point of coil and positive of diode to negaive of set/reset coil.. Please correct me if I am wrong

 

<offtopic><rant>
If you’re going to respond, why don’t people read the entire thread? I’ve been guilty of this myself, but providing an answer like you’re the grand master expert, an answer which has already been proposed... just grills my hot dog !
</rant></offtopic>

I don't know why they don't read the entire thread..

 

just grills my hot dog !

Awe geez! You HAD to mention "Hot Dogs".

 

will this diode do the job ?
https://eu.mouser.com/ProductDetail/ON-Semiconductor/1N4001RLG/?qs=y2kkmE52mdNtNRrsA1ylQg==
The wiring would be to connect negative terminal to common positive point of coil and positive of diode to negaive of set/reset coil.. Please correct me if I am wrong

Please correct me if I am wrong!
Thank you

 

Please correct me if I am wrong!
Thank you

the cathode connects to + (plus) of relay coil
the anode connects to - (minus) of relay coil

i’d be more comfortable with a 1N4004.

 

’d be more comfortable with a 1N4004.

Why do you want a diode with more that a 50V rating, as there's never more than the supply voltage appearing across it?

 

Why do you want a diode with more that a 50V rating, as there's never more than the supply voltage appearing across it?

BEMF doesn’t spike higher than the supply voltage?

 

Why do you want a diode with more that a 50V rating, as there's never more than the supply voltage appearing across it?

The rule of thumb is PIV 10 times the operating voltage but that doesn't mean it won't go higher.
The TS may want to use a higher operating voltage relay for whatever reason (he's already changed it once). Theres no significant cost difference between the two type of diodes. My preference is 1N4004.

 

If you want to try using a flip flop, here's one way. It's more involved though than using a toggle switch and passive circuit.
The button is an ordinary momentary NO push button. R3/R6 set the pulse duration.
You can add LED indicators in parallel with each coil to indicated status (as long as it doesn't need to be fail safe).

The CD4013 comes with two FF in a package, so I used one to square up the PB input signal.

View attachment 227964

Hey, It would be more helpful for me if u could share this LTspice file. Thank you

 

Here's a thought: Since the relays will not be live switching, neither would a switch. As long as you get a switch rated for the working voltage across the coil you should be fine. No need for relays or indicators or push buttons or caps or Flip Flops. The switch contacts will be either closed or open. As long as they can handle 40A, you're good to go. And the switch position should be plenty indicator of which position the switch is in.

 

Here's a thought: Since the relays will not be live switching, neither would a switch. As long as you get a switch rated for the working voltage across the coil you should be fine. No need for relays or indicators or push buttons or caps or Flip Flops. The switch contacts will be either closed or open. As long as they can handle 40A, you're good to go. And the switch position should be plenty indicator of which position the switch is in.

Yea i considered this option but I could not find the switch which is rated for 40A. I did find few but it was big and doesn't fit on pcb

 

Another consideration: 40A will require a 10 gauge wire for a short run.

 

Another consideration: 40A will require a 10 gauge wire for a short run.

Yea.
<Off topic>
What is the minimum size of the litz wire required for winding the inductor at 40A?