Minimum number of relays per h-bridge

[ramonegumpert]

Hi experts,

Is it possible to form a h-bridge using 2 spdt relays?
What i can find on the net are h-bridges using 4 spst relays or using other types of relays.

sincerely
Ramone

 

[skeptic2]

What do you think? Would it be possible to construct and H bridge with 1 DPDT relay?

 

[Bob S]

Yes. You need to choose between "make before break" (Form D) or "break before make" (Form C) contacts.

Bob S

 

[ramonegumpert]

What do you think? Would it be possible to construct and H bridge with 1 DPDT relay?

i think it is possible and connected one to test but the motor did not operate bi-directionally according to plan. That is why i wanted to confirm this.

 

[ramonegumpert]

Yes. You need to choose between "make before break" (Form D) or "break before make" (Form C) contacts.

Bob S

Thanks Bob S!

 

[Bob S]

i think it is possible and connected one to test but the motor did not operate bi-directionally according to plan. That is why i wanted to confirm this.

On certain motors, like fractional HP induction motors (capacitor start, split phase, repulsion start), there is a starting coil and a running coil. If you try to reverse the motor at full speed, it won't. It has to slow down until the centrifugal switch engages, and preferably until it stops before you reverse it.

Bob S

 

[vk6kro]

Hi experts,

Is it possible to form a h-bridge using 2 spdt relays?
What i can find on the net are h-bridges using 4 spst relays or using other types of relays.

sincerely
Ramone

Yes, see the last entry in this thread:
https://www.physicsforums.com/showthread.php?t=381478

You would just connect the two coils of the relays in parallel or in series and switch them at the same time.