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[John W E]

This is for all you plastic magic lads and all those who have used the electronics in an 'old' servo as a speed controller. 

This is my idea; to strip an old servo down that is still working and use the electric motor to actually propel the model and the electronics of the servo to give me forward and reverse;   I am not certain of and hope the lads of the forum may be able to answer; I do realise that the size of the motor is going to be limited, but, has anyone any idea of how big a motor you can use without destroying the electronics; e.g. I was thinking of a motor that would draw between 1 - 1.5 amps.   

aye
John E
BLUEBIRD

[HS93 (RIP)]

I know you want to us a servo but Action' do a micro  1 A Miniature Microcomputer soft start SPEED CONTROL (P52A) - PCB Kit with case £10 this will do the same


Taken from there site I hope he does not mind.!!

 micro 1’ is a highly efficient little relayless, two IC   Speed controller for very small motors. Suitable for use with any standard R/C outfit. It can run from 4.8 Volt Nicad or 6 Volt Dry receiver batteries from where it gets the power for the motor (plugs in like a servo) It has a maximum  current of 1 Amp. In any event, it is self protecting with ‘Failsafe’, ‘overtemperature’ and ‘overcurrent ‘shut down (not REVERSE VOLTAGE). In stop condition the current drops to a ‘Sleep’ value which is very low. It will cope with a wide range of small, efficient motors, many Radio boat modellers are using 5v cassette recorder motors, it is ideal for them.  ACTION  MOTORS M5 or M7 are also ideal. Full PCB kit with case only 40mm x 27mm x 17mm. Less servo lead and wire. also built £15

 CONDOR 2' 2A  Mini AUTOSET Computer SPEED CONTROLLER (P78) - PCB Kit with case & screw connectors

 

Tiny Computer 2A peak Speed Controller for small scale model boats, recommended for 360/385 type and similar motors. A n enclosed unit with no relay projection,  MICRO IC and POWERFET, forward and reverse, 2 Amp  peak. The relay coil takes it's power from the receiver battery which should be 4.8 Volts to  6 Volts. One  version covers the main MOTOR drive voltage range of 2 to 12 Volts which should cover most boat models. No adjustment required AUTOSET centre stick setting. Fixed GENTLE acceleration. Screw block connections for Motor and Power. It is easy to build. Motor stops if signal lost or receiver switched off. External size -Size 41mm x 31mm x 20mm. Full PCB kit including ABS case, less power wire and servo lead. (MOTORS? see Price List)   A MINIATURE SCREWDRIVER REQUIRED TO CONNECT.  Weight with case 26G  weight without case 16G


They both work well and you can use a biger motor with them I think you are on the limit with a servo motor running for long periods so you would not be able to change motors  but I may be wrong ..Peter
 
http://www.actionkit.co.uk/


 

[barriew]

I would agree with HS93, use one of Action's small speed controllers. Using the electronics from a servo makes it very difficult to set the null position, unless you also replace the pot with a multi-turn variety. The motors seem OK, but again using one of Action's ESCs you have more flexibility in choice of motor. I think Craig still sells cassette recorder motors which are small and reasonably powerful.

Barrie

[John W E]

hi all,

After reading above comments Ive decided on the ACTion so - just been on the phone to ACTion this morning and ordered a PICO tiny linear speed controller - cant argue at the price - just a tenner and 2 quid postage - wonder if the postman will bring it today 

aye
john e
bluebird

[malcolmfrary]

The electronics in most servos is limited to 0.5 amp, and to a nominal 6 volts (either 5 nicad cells or a 6 volt lead acid or 4 dry cells).
Obviously the servo motor will work, CD platter motors also work well, and have a longer spindle for easier coupling.  The other motors recovered from a dead CD player are OK as long as they are DC motors and not stepper motors.
I have used an extra circuit for several years to enable higher voltage and heavier curent, but nowadays it's almost as cheap to use a "proper" controller, and certainly less bulky.