Picture of 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!
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Step 1: The circuit

Picture of The circuit
This is a diagram of what we are building. This and many other 555 circuits can be found on

Step 2: What you need

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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

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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

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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?

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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

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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.

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

ferjanyen1 year ago
Nice project, please let me know when you got the wi-fi sorted. Thanks.
wiredcav1 year ago
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.
gfetters (author)  wiredcav1 year ago
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.
tcarney571 year ago
Very nice. Are the resistor values chosen such that the servo turns faster forward than in reverse?
gfetters (author)  tcarney571 year ago
No it should be the same in either direction.
Poppy Ann1 year ago
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.
gfetters (author)  Poppy Ann1 year ago
Excellent Idea.
EDLITE1 year ago
You have gone to quite a bit of trouble when you can buy a nice Turnigy servo tester at Hobby King for 6 bucks!
gfetters (author)  EDLITE1 year ago
Its nice to build once in a while instead of buy. I could have easily done this with an arduino too.
a great adaptable circuit for solar tracking (improved solar panel efficiency) or astronomical tracking. thanks.
askjerry1 year ago
Our robot group was looking for something simple/kool to do... I think this would be a good project for some of the new folks. thanks! great job!