|Home > Circuits > Other > Simple Servo Controller|
Servo motors have many uses in everything from robotics to puppetry to photography and beyond. These little motors can position their output shaft to any position on command and hold that position. Most servos have a range of motion to about 210 degrees and thankfully are very easy to control with a simple circuit such as the one presented here. Using just a 555 timer and a few support components this circuit can control a servo through it's full rotation based on the position of a pot. This circuit was originally published in the Think Tank column of the October 1995 issue of Popular Electronics.
|Add A Comment|
|what should we give in the controller?? i mean how should be the input?? could you give a table of inputs and the angle turned???|
|yesterday i assemble this ckt .this ckt does not work when i inserted the R2 resistor of 68 kilo ohm wit base of transistor in series|
|I need some help changing this circuit. I have a single on of switch and want to us it to set the servo to minimum and maximum by simply turning it on or off. Will proley be good to have a variable pot in order to set the minimum/maximum position to fine tune. Please advise. I wanna make a number plate flipper for my bike with a servo. So On must be flipped up and off must be flipped down.|
|Question : can the other comparator be used to sense voltage drop in the vcc,and set different values for pin 6,as to make it switch H and V skew depending on receiver polarity?|
|I would like to suggest to add an IC where the pot is,and use the 13v/18v as reference to vary the resistance between 2 states for U1,in this way,you can feed the power from the LNB cable,and it will be possible to change skew according to polarity automatically.,with no power supply needed.|
|Normaly, it will work with all kind of servo, maybe not with the digital ones..?!! But, like said in the comment uper, it is just a question of wire's color !|
|is it working in other servo motor or only in Futaba servos?|
|Schematic not to clear U1 (555) Is Capacitor C1 postive side connected Pin (1) and to Pin (2) and Pin (6) of U1 (555) chip? mrel|
|Just like craig and john said earlier...I have the same problem too.All I need is to control the motor from 90 to 0 and 0 to 90.But my servo twitches once whenever I switch the circuit on.Please help me|
|I hooked up the circuit on a proto board--it works pretty well, but I found it sort of noisy. In "Practical Electronics for Inventors," by Paul Scherz, it shows a 1000uF cap across the positive and negative inputs to the motor (page 933 of 2nd Edition). I tried a 5uF one and it cured the noise.|
|graig asked can he make the servo go from 0-90 and 90-0 i have a similar problem on a railway signal but wish to use a double throw switch help please john|
|I built this circuit,and it does not work.Nothing at all happens.|
|Thanks for posting this circuit, it works great. I am using it to adjust the skew on a C band satellite dish. For my particular application, I found the maximum and minimum values of R5 to be ideal: Rmax: 2.947K Rmin: 909 Any resistance outside of that range, and the circuit attempts to drive the servo motor past it's mechanical limits. The values, in your particular application, can be found experimentally.|
|R3 should be change to 1K resistor to get the minimum time of positive pulse equal to 1.4mS and the maximum time is equal to 2.1mS...so it suitable for servo motor running...|
|I like to spend much time in the Internet, but, unfortunately not often find something worthy and interesting to read. I liked the way you covered the topic and depth with which you explain these important things. Hope you will like it.|
|At first I didn't get any movement, then I disconnected the linkage between R5 and pin 2 of the IC, and C1. Now, like someone else said, the servo just twitches once. Any ideas, anybody? Jerry, how'd you manage to get this to work?|
|I have built this circuit and it works well. Did you know that you can connect pin 4 to pin 5 instead of pin 8. This just simplifies the PC board layout.|
|if the value as ff r3=10k, r4=1k, r5=1k n c=0.000001F this should be result to Freq=103.07153164296022 Tlow=0.001s Thigh=0.008s.. assume the values are correct.. the servo feeds on positive pulse. The out put from pin 3 of 555timer will trigger the transistor in positive pulse that is 0.008s? how can the servo work with that? If im not mistakern the servo need :1ms for 0 degree, 1.5ms for 90 deg, n 2ms for 180 deg.. can someone explain this? I need help to analyze this prob thanks|
|Question: I turn the circuit on and the servo it twitches once or twice. Then it doesn't do anything. What could be causing this? One comment says R1 and R5 need to corrected. Is this refering to there position on the Schematic?|
|How can I make the servo go from 0 to 90 and then 90 to 0. It is to control a minature figure in a display.|
|i like simple project|
|In the Misc. and Notes "R1" should be corrected to "R5".|
|All comments are being shown. Show Only Last 10 Comments.||Add A Comment|
If you would like to leave a comment, you can do so using the form below. Comments can be things like suggestions, successes or failures, improvements, similar circuits, error reports, an answer to a previous commenter's question, or anything in between. However if you would like to ask a question it is suggested that you use the forum instead. The forum provides a more robust environment for discussion.
Important: If you post a technical question here, there is no guarantee it will be answered. All technical questions should be posted to the forum. The owner of this site generally does not answer questions in comments.
All comments are subject to approval before they are displayed here, so your comment will not appear immediately. This is done mainly to prevent spam and other abuse. If you wish to remain anonymous, simply enter "anonymous" for your name and/or email.
Back To Circuits Page | Mail Me | Search