Cheap and easy speed controllers

[aliboy]

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

[maddox]

Cheap and easy speed controllers

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

[ewan]

Cheap and easy speed controllers

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.

[aliboy]

Cheap and easy speed controllers

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

[woody]

Cheap and easy speed controllers

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

[aliboy]

Cheap and easy speed controllers

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

[ewan]

Cheap and easy speed controllers

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.

[robjones]

Cheap and easy speed controllers

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.

[ewan]

Cheap and easy speed controllers

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

[aliboy]

Cheap and easy speed controllers

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

[Guest]

Cheap and easy speed controllers

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.

[knightrous]

Cheap and easy speed controllers

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.

[robjones]

Cheap and easy speed controllers

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!

[big_nipper]

Cheap and easy speed controllers

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.

[m2xt]

Cheap and easy speed controllers

Well thats spooky, http://www.technobots.co.uk>Technobots