|H bridge drawn as a conventional bridge|
0 0 nothing happens
0 1 goes down
1 0 goes up
1 1 nothing happens
We kind of waste one state in the two bit control but you just have to live with that.
An H bridge motor control IC is one of the very basic components used in home electronics like VCR's since forever. SN754410 is a 'modern' dual H bridge. PDF datasheet. It has two 1A bridges that can control a 4.5...36V power rail by 5V CMOS/TTL compatible logic input. Perfect for us.
Playing with the crab was not very surprising. It wastes 1.4 volts as two transistors in serial are expected to waste. A bias current of 20 mA was unexpected. Not so harmful but we don't need it. I assume the bias is for maximum speed that we don't need.
A 16-pin DIP package can handle 2 watts of power in 'normal' conditions. 2 watts / 1.4 volts / 2 motors = around 0.7 amperes each. It seems that we are in the ballpark.
We can use SN754410 as a driver. However it would be good to either
- Drive one motor per one SN..blah..blah..
- Add some small heat sinking