Hi all,
The fancy electronic chariot posted by Guenther made me say : hey, I didn’t post a diagram yet of an H-bridge !
A H-bridge is a circuit which enables a motor to turn clockwise or counter clockwise by pushing a single button.
I propose here an electro mechanical version using only 1 relay.
This is possible thanks to Lectron who made a relay having 2 separate contact switches.
Here’s the diagram :

As you see from the circuit, the meter is used here as an indicator for the flow of current.
You can use a small 9V DC motor instead.
R2 is used here to protect the relay from excessive current (the relay coil is designed for 5V).
By pressing the switch, you can see the meter needle move from one side to the other, indicating a polarity switching.
Greetings
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This topic was modified 4 years, 11 months ago by Michael. Reason: Changed font and size styling for easier reading