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hi
i was wondering is it possible to make your own speed controller for £20-£30. Is it possible to use a tamiya 3 terminal speed contoller on 2 12v drill motors.Also i have heard people make there own speed controller from their drill triggers . How is this done ?
Ali
Ask cavecrusher.
he can provide pictures and a guideline.
You can find him by asking on the Dutch forum.
http://rw.bugs.nlhttp://rw.bugs.nl
Ali, didnt you buy an IBC? Also I would definately not advise Hobby speedos for robots, most (if not all) of them arent designed for the job. Best stick with Electronizes as the cheapest RC speedo.
There are loads of ways you could make servo-operated switches or even servo operated potentiometer but you wont get very good performance at all compared to a mosfet/H-Bridge circuit.
Ewan you are correct i did buy a IBC i just wanted to know if theres a way to make cheap speedos for my upcoming projects. Any diagram pictures would help
Ali
http://www.kleefeld.freeserve.co.uk/model/barry/pic01/rc_speed.htmhttp://www.kleefeld.freeserve.co.uk/...1/rc_speed.htm
http://www.mcmanis.com/chuck/Robotics/http://www.mcmanis.com/chuck/Robotics/
http://www.shucksmith.com/page-forklift-hbridge.htmlhttp://www.shucksmith.com/page-forklift-hbridge.html
ok i think i know how to build one i need 2 x SPDT relay , some micro switches and 2 servos .Am i correct ? Will this work? How do i wire it up
Look at a few sites on the net to find some schematic diagrams of how the relays wire up. You will need to mount the servos in a good position to switch the microswitches and you might find strip-board, available from places like maplin, useful for the relay mounting. Obviously that would only be classed as an RC Switch rather than a speed controller.
Im experimenting with this at the moment and thanks to everyone in the robot community thats helped so far. When Ive finished Ill post everything online including the pic code and means to download to your pic for pennies. So far Ive made a simple 5Amp weapon switch using a PIC for under a fiver. A beefy weapon pic controlled Rx switch (40A) for under a tenner, a single channel speed controller 30A continuous using PIC/H bridge mosfets for about £12. Im still developing a single board two motor controller with 8 mosfets and two pics that hopefully will cost only about £35 to make. Why am I doing this? I run the Young Engineers Club at my school and my students need cheap stuff! And Im sick of seeing kids have to shell out £75+ for decent speed controllers.
Ive spent the last four days building prototypes and the pile of dead components is growing :sad:
Ill put up all the How to stuff on my website when its sorted, including the PCB masks.
Are you using H-bridge driver chips run by the pic by any chance? It helps greatly to use an extra 10v to the upper n-channel mosfets while switching. The standard for motor controllers like this seems to be the HIP chips
Regards, Ewan
http://www.micro-maul.co.ukhttp://www.micro-maul.co.uk
http://www.picaxe.co.uk/www.picaxe.co.uk/ this looks good is this any use? also http://homepages.paradise.net.nz/bhabbott/esc.htmlhttp://homepages.paradise.net.nz/bhabbott/esc.html
Right, PICAXE i bought £50 worth of this stuff a while ago, ive not actually started messing with it yet, ill warn you now, the manual for it (which you have to print off yourself) is 400 or so pages!!
Basically its programable ics, although you dont have to remove the ic to program it, all you need to do is put a stereo jack socket, a slider switch (instead of a little jumper) and a couple of resistors on every circuit board you make. Then to program it you use a serial lead (that jas a stereo minijack on the other end) link it to your computer and the write the camands.
Im not sure if its good enough for larger robotics use, (its certanly ok for antweight type robots)
One day ill get to have a mess with it LOL.
If your going to learn about it i suggest you start off with the 8 pin picaxe ic and then move onto the 18 pin.
Start with the PicAXE 08M. The 08M has a single analog input (you use this to put you reciever signal in) and has a single PWM output (you use this to drive your fets through either a HIP chip or a Darlington Transistor bank). The 08M inly a smidgeon dearer, but is great to use. Im currently playing with the 08Ms to make a PWM speed controllers with 70amp relay reverse.
Im also using the 08M chips, only £1.50 and have an 8 bit pulsin giving a linear range of about 90 steps for my Hitec Tx, and the PWM out is OK. The debug command is useful and the serial cable is only £2.50. The software is free.
Im trying to avoid using the HIP4081 to keep cost down. You can use an cheap motor driver chip (L293) or a UNL2000 series darlodriver. Dont connect your mosfet straight to the PIC like I did!
Rob, to make it cheap you could actually connect the pic output directly to a mosfet (through a current limiting resistor) for the low side for controlling the direction and use a bootstrapped high side driver IC for the high side mosfets in PWM mode. Drawback is you can only go to about 90% PWM but you could use protected mosfets for the low side for current & temperature protection as an option without changing the circuit.
As you already know Im designing a feather speed controler as well but it wont be cheap.
Well thats spooky, http://www.technobots.co.uk>Technobots
that is really weired i mention it and then it appers hmmmmmmm....gold plated toilet :P
while searching i came across these http://www.robot-electronics.co.uk/shop/Motor_Controllers2008.htmhttp://www.robot-electronics.co.uk/s...ollers2008.htm are they any good for a FW ?and is that a good price to pay for it? has anyone else used them before?
Those are the ones technobots has started selling, so youll probably want to buy from http://www.technobots.co.ukwww.technobots.co.uk
That price doesnt include heat sink I dont think and a 2 Channel heatsinked version will set you back at least 70 pounds probably. Itll probably do about 15A with heatsinking so youll want to keep away from any bigger motors. Current limiting at 20A on the single h-bridge controller is probably too low for most decent featherweight motors.
Ewan, I would have thought that 20A @ 24V i.e 500W per motor should be adequate for most feathers. I have yet to make a heatsink for the 2-channel version but I expect it to be suitable for the 8 motor / 8 wheel drive Zeobot but as you say, keep it away from larger motors.
Ive just read one of the entries into the featherweight database (Kang) and it says it uses drill triggers to control the speed of the motors. I thought about using these as speed controllers but I wasnt sure how to connect both the speed and direction switches. Assuming that the drill controls have the trigger for speed and the slide switch for either forwards or backwards, whats the best way to connect them up so as to have both speed and direction control? Is there a way to modify them so that you dont have to slide the switch across (which would be murder to remember in the heat of a battle) or do you have to connect them both upto servos or something? I know they arent the most practical speed controllers around but it would be handy to have them fully operating.
Many regards,
Jamie :)
yes you use 2 microswitches that actuate before pushing in the trigger in place of the mechanical switch. one micro for foward direction one for reverse
the drill triggers current limit at ~15amps and are full variable speed. BUT they are very fiddly to make.
the work well and even if you do blow out the fet which is unlikely you can still use it as a full on off power switch.
ill let aaron chide in here on how to make them and post a photo because my versions are only half built but be warned they are damn tricky to make
yes you use 2 microswitches that actuate before pushing in the trigger in place of the mechanical switch. one micro for foward direction one for reverse
the drill triggers current limit at ~15amps and are full variable speed. BUT they are very fiddly to make.
they work well and even if you do blow out the fet which is unlikely you can still use it as a full on off power switch.
ill let aaron chide in here on how to make them and post a photo because my versions are only half built but be warned they are damn tricky to make
My team mate Andrew was the genius behind using the XU1 variable speed drill triggers for controllers. We didnt actually realise that they were 15amp current limited till we stall tested a set and noticed it wouldnt feed ore then 15-17amps at most.
Something inside the little trigger cuts back the postive voltage to limit current, was quite interesting to play with. Andrew now builds them to fit inside the drill battery case for easy of mounting :proud:
Cool, thanx for the replies, Ill see what I can do with mine then (probably melt them into oblivion or something :))
Regards
Jamie
ive just made my own speedcontroller cost bout £90 (bout 3xs the amount u wanted to spend lenny) and that was with some of the bits already owned. building speed controllers are hard and very time consuming mine was all surface mount tests ya patence tho :P. i now probably have the most complicated speed controller ever in my featherbot :P gotta big up somthing bout me feather.
triggy