Transistor Circuit to Operate Relay from Arduino Uno

[Robert Atkinson 2Participant @robertatkinson2]

The noise from a stepper depends on the motor and it’s mounting more than the drive method. For a simple low torque application like a clock there is n need for a H bridge or a specialist driver. Just a bipolar motor and four low side MOSFETs. This gives half steps with simple code.

Robert.

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

The noise from a stepper depends on the motor and it’s mounting more than the drive method. For a simple low torque application like a clock there is n need for a H bridge or a specialist driver. Just a bipolar motor and four low side MOSFETs. This gives half steps with simple code.

Robert.

There is if you need to play games with the ratio to avoid mechanical gearing.  On my ‘Nome-based clock the stepper operating the gravity arm needed microstepping to start cleanly and to get low noise.  I would suggest that actually using a “specialist” driver is actually much easier for a beginner than trying to use discretes.  Just set the drive current and microstepping ratio once, then apply power and step pulses.

[duncan webster 1Participant @duncanwebster1]

For driving unipolar stepper motors I’ve used ULN2003 chip. 7 Darlington transistors with built in flyback diodes on one 16 pin chip. Much easier than using separate FET or transistor. Handles 500mA which is plenty for driving a slave clock

For bipolar (4 wire) motors I’ve used dual H bridge chip. When my PC problem is fixed I’ll be able to look up the number.

I’m sure there are Arduino libraries for doing t, but I wrote my own using bit twiddling on PortB.

The 48 step motor I used in my slave clock came with a 15t cog, which looked a bit difficult to get off, so I meshed it with a 75t gear on the minute shaft and advance once per 15 seconds. Then I got ‘clever’ and advanced it 4 steps every minute, why, just because I could.

As far as using electromagnets and ratchets, that’s what Gents and Synchronome slaves do, the noise isn’t too bad, quite a feature in fact

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