Robin Coombs Posted September 17, 2009 Share Posted September 17, 2009 Hi all. I am in the process of designing my own electric retracts. The reason is: 1. Available units are very expensive. 2. I love messing in my workshop. My problem lies with the control. I am using a small electric motor with a screw jack arrangement. How do I get the signal from the radio retract switch to reverse the motor ploarity for direction? How can I get the current to stop flowing at the end of travell without using limit switches. I know ther are some real boffins out there that may just be able to point me in the right direction. If there is a prodiuct on the martket, what is it? Cheers Robin Quote Link to comment Share on other sites More sharing options...
birdy Posted September 17, 2009 Share Posted September 17, 2009 I'me not much good at all this electricity stuff, but I have had the following ideas: -use a Light dependent resister and an LED to provide the "switch" on each end -CMOS electronics would be most suitable at RC voltages -I saw some kind of on off radio controled switch a while ago, for things such as lights, but I cant think where - if you could find this you could use a transister to change this into a digital high and low voltage, although you would also recrire a supply from somewhere else. help this might help (thought it probs wont!) birdy Quote Link to comment Share on other sites More sharing options...
Martin Shoebridge Posted October 5, 2009 Share Posted October 5, 2009 Without limit switches, it's tricky. Do you mean no sort of switch at all ? i.e. opto as above?The only other way is to current sense, but that has it's own problems.... sticky gear mid way might indicate a down lock... All in all, it's no simple task, even for an accomplished electronics engineer.. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted October 5, 2009 Share Posted October 5, 2009 If you use brushed motors you could use a car/boat ESC with a reversing feature, but the motor would then stall at the end of the travel. Maybe you could set it up with a timer which would cut the current after a set time and then reset itself when the retract switch is reversed. Just remember to use a separate battery for the motors though as you would not want to inadvertently flatten the Rx battery. You might also be able to use a stepping motor and controller, but I'm not sure, have a read here http://www.anaheimautomation.com/products/stepper/stepper-products.php?gclid=CNrropPApp0CFaAA4wodbHmy1w Edited By Frank Skilbeck on 05/10/2009 19:11:14 Quote Link to comment Share on other sites More sharing options...
Brian Parker Posted October 5, 2009 Share Posted October 5, 2009 If you want to avoid relays and switches then you need Logic. Use the logic gates to give positive volts for down, negative volts for up, zero volts for stop. A drive circuit will be needed to enable the logic to drive output transistors to the motor. You will also need two batteries connected so as to give positive voltage, negative voltage and also zero volts, plus opto devices for control. This is quite standard stuff and there is sure to be a circuit on-line somewhere. Stepper motors are a possibility but on-board control would be necessary.Edited By Brian Parker on 05/10/2009 20:51:39 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.