Subject: Re: Servo question... From: filip@alpha.smi.med.pitt.edu (Filip M Gieszczykiewicz) Date: 7 May 1995 23:26:44 GMT In Article <3oji12$cpk@nitrogen.mankato.msus.edu> thus spoke nimrod@krypton.mankato.msus.edu (Corey J Kovacs): > Hi all, I've been trying to use some model airplane servos with >my miniboard, as well as the parrallax basic stamp but no luck, all they >do is sit there and jitter. I am powering the servos seperate from the >board, and getting only the signal from the board. of the red white and >black wires, i understand that the red and black or power and the white >signal, is this right? sure would be nice to use these features eh? i >even went out and bought a new one (FP-S148) cuz' I fgured maybe ALL my >servos were bad, well, same thing, jitter jitter, what the heck am I >doing wrong....oh yeah, frequency was set to 50 hz and duration 1 to 2 ms >for the travel.. Greetings. For the last one, you have to connect to my WWW page. The servo link is at URL: http://www.paranoia.com/~filipg/HTML/RC/F_Servos.html -----------------chop-with-axe----------------chop-with-axe--------------------- VARIOUS INFORMATION ON SERVOS V1.01 Contents: * Servo Cross-Reference Chart * Servo clock source * Servo Driver Circuit needed * Servo Controller Schematic and Code _________________________________________________________________ SERVO CROSS-REFERENCE CHART (From Julio C. Chacon, Jr) Someone kindly asked me to post this, so here goes.The Novak Input Plug System is very useful if you need to swap plugs to use different servos on different radio systems. The different plug styles in the kit are individually marked. In addition, the plugs are marked "WHT, RED, BLK" in the appropriate order that they should be installed on the plug. for reference, I'll place these at the top of the chart: RED(+) BLK(-) WHT(signal) === === === Airtronics Red Black Brown Sanwa Red Black Black [*] Futaba J Red Black White KO Propo Red Black Blue Kyosho/Pulsar Red Black Yellow Japan Radio(JR) Red Brown Orange [*] I've never seen one, so don't ask! And there it is! All you have to do to replace the plug is make sure that you place the corresponding wire in the proper location as marked on the connector. For example, if you have a Futaba servo that you'd like to use on an Airtronics receiver, simply take the Airtronics connector from the kit, and and stick the Red in RED, White in WHT, and Black in BLK. If you don't have the input kit, but you have two servos, you should write down the order of the wires as they appear on the Airtronics servo, then remove it. Next, you would remove the plug off of the Futaba servo and install the Airtronics plug by inserting the White wire where the Brown one was, then the Black to Black, and Red to Red. I Hope you make use of it! By the way, this chart is included with the N.I.P.S. _________________________________________________________________ SERVO CLOCK SOURCE o 5VDC | 5k pot 4.3k | x---/\/\/\/\/\/--------/\/\/\/\/\-----------x------x | ________|______|_______ | | 4 8 | x----------------------------------|7 | | 1N457 diode | | output x--------->|---------------x-------|6 3|------------------ | | | NE555 | | 68k | | | x---/\/\/\/\/\/\/-----x----x-------|2 | | |_______1_______5_______| | | | _|_ | _|_ ___ 0.33uf | ___ 0.1uf | | | x----------x---------x-------x | | ----- --- Gnd - _________________________________________________________________ SERVO DRIVER CIRCUIT NEEDED Here's a circuit that's older than dirt, but it works quite well. +V o-------o--------o----o-------------o----o-------------o-----o +V | | | | | | Gnd o R1-100K | | | | R4--> R3 o Gnd | | | | | | 4.7K 10K | | | |--------| |---------| | | | | | | 4 8 | | 5 14 | | | | o------|7 | | 11|-----o | | R2-15K | (555) 3|-----o---|3 | C2-0.22mF | | o------|6 | | | (74121) | | | | | | 2 1 | +---|4 10|-----o | | | |--------| | 7 6 | | | | | | |---------| | | o--------+ | | | | | | | | +--------- Servo | | C1-0.22 mF | | Signal | | | | | | +------ o-------------o-------------o------------------------+ Notes: 1. R3 is a 10K pot, connected as a variable resistor 2. Increased value for R1 -> less angular throw @ R3 3. Servo signal (Pin 6 of 74121) is for 'positive-going' servos (Use signal @ Pin 1 for negative-going servos) It would be simple to connect an external pot instead of the internal 'feedback' pot (most servos use a 1.5K pot), but you'd still have to provide a means for the pot to be rotated by the gear train. Remember, the servo is a 'closed loop' feedback system. _________________________________________________________________ This article compiled by . The most recent version is available on the WWW server http://www.paranoia.com/~filipg [Copyright] [Disclaimer] ---------chop-with-axe----------------chop-with-axe--------------------- +-->Filip "I'll buy a vowel" Gieszczykiewicz | E-mail: filipg@paranoia.com | http://www.paranoia.com/~filipg | Sci.Electronics, RC, Misc FAQs + MORE! | Enjoy your job, work within the law, make lots of money : Choose any two. | Making money with CS and spending it on robotics, life & friends. !NOT(!PC)