The discussion confirms that it is possible to construct an H-bridge using two SPDT (Single Pole Double Throw) relays. Participants emphasized the importance of relay contact types, specifically "make before break" (Form D) and "break before make" (Form C), in ensuring proper operation. Additionally, the challenges of using certain motors, such as fractional HP induction motors, were highlighted, particularly regarding their inability to reverse direction at full speed without stopping first. The conversation also referenced a related thread for further insights.
PREREQUISITESElectronics engineers, hobbyists building motor control circuits, and anyone interested in relay-based H-bridge designs will benefit from this discussion.
skeptic2 said:
Bob S said:
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.ramonegumpert said:
ramonegumpert said: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