Drive Servos With a 555 Timer IC

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Introduction: Drive Servos With a 555 Timer IC

This instructable provides a walk through of a basic servo driver using a 555 IC chip 5 resistors a transistor and 2 capacitors.  The idea is simple, use 2 switches to control the motion of the servo. Note this circuit is based on a servo tester circuit found on the Internet. We built this with parts from Jameco Electronics at an instructables build night at Arch Reactor Hackerspace. Thanks Jameco!

Step 1: The Circuit

This is a diagram of what we are building. This and many other 555 circuits can be found on www.555-timer-circuits.com

Step 2: What You Need

555 IC 68k resistor 4.7k resistor 33k resistor 10k resistor 1k resistor 2 - 100n capacitors bc547 transistor 2 momentary push buttons a servo a 6v power supply jumper wires. LOTSOf them.

Step 3: Wiring

wire the circuit as in this image. Be sure to lookup your transistor and match emitter, collector, and base as in the circuit diagram. Do not hook the power up until after it is wired. Refer back to the circuit diagram as needed to clarify wiring questions.

Step 4: Add Power

Connect power to the red and black rails and press one of the buttons. You should see the servo move in response to the button press.

Step 5: How Crowded Can It Get?

It's a good idea a breadboard this out and simplify afterwards. It's a nice quick project to get you started on servos.

Step 6: Optional

A meter is optional but can really go a long way in helping you resolve issues. I highly recommend getting one for any of you circuit projects.

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    24 Discussions

    This is a much better idea. It allows you to tune the resistance. I definitely like it.

    0
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    ZigZ5

    8 months ago

    How far can i run the servo wire? Im trying to set of a pan and tilt camera just about 20 ft away.

    1 reply

    There is a limit to how far you can run servo wires. There is a drop over distance and the size of the wire effects it too. That being said you can run servo wires a long way like 50ft or so. I would try it first. Get your 20 ft of wire stretch it out and test it. Unshielded wire can act like an antenna too so you might want to add a ferrite core to the line if you see the stepper acting funny.

    Hi, can you tell us how can we have control over the vitess of the motor using this circuit??

    I made the circuit but It works only in forward bias. I used all the same components and a 5 v DC power supply

    I used an 180 degree servo but this would work with a continuous servo. two 100nf capacitors.

    what type servo motor did you use? i mean 180 degree servo motor angle or continous servo motor? the list of component of the capacitor is 2 100nF or 1 100nF and 1 10nF?

    what type servo motor did you use? i mean 180 degree servo motor angle or continous servo motor? the list of component of the capacitor is 2 100nF or 1 100nF and 1 10nF?

    what type servo motor did you use? i mean 180 degree servo motor angle or continous servo motor? the list of component of the capacitor is 2 100nF or 1 100nF and 1 10nF?

    Just out of curiosity, what frequency is the PWM being driven at? Roughly 10kHz?

    Nice project, please let me know when you got the wi-fi sorted. Thanks.

    Very nice project. I presume you're sending two PWM signals corresponding to two servo positions - yes? I would think I could replace the two resistors and switches with a potentiometer that would allow me to drive the servo to any position. Is this right?

    Thanks for a cool project.

    2 replies

    You are correct. A potentiometer is an excellent idea as a replacement for the 2 push buttons. I am thinking of adding a WiFly to this so I can control the Servo via the internet.

    Very nice. Are the resistor values chosen such that the servo turns faster forward than in reverse?

    1 reply

    I was trying to do this circuit a couple of years ago as i wanted to use a brush-less model motor and propeller as a fan on my boat but when i found out i can buy a servo tester for $4.50 i just used them instead as the cost of 12 volt fans was around $15 for a cheep car one or $55 for a boat one and they only last around a year as the brushes always wear out but the model motors last forever and use less power to move more air plus i can control how fast they run which is great so they do not make as much noise as i leave some of them running all night.

    1 reply