Model Boat Mayhem - Forum

Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: pipster on February 16, 2019, 10:46:46 AM

Title: ESC or reversible switch for 1.5v motor
Post by: pipster on February 16, 2019, 10:46:46 AM
Hi,
I'm planning to use 1.5v motors on a Hiab crane.  Does anyone know of a suitable reversible ESC or RC switch unit?  So far I've only found ESC with a greater voltage requirement or a one way switch.
Cheers
Phil
Title: Re: ESC or reversible switch for 1.5v motor
Post by: chas on February 16, 2019, 11:13:08 AM
How about the action electronics P 78? It's OK from 2 to 12 volts.
Chas

Title: Re: ESC or reversible switch for 1.5v motor
Post by: John W E on February 16, 2019, 12:48:51 PM

hi there


Have a look at this Company; Mr R C World - I am using a couple of their mini speed controllers to control a crane on a diving support vessel - one of the things that is built into them is a safety feature where if you move the stick too fast on your TX stick controlling one of these, there is a slight delay before it actually starts up.  This is built into the unit just as a safety feature - it is all explained in a leaflet which you get with them and the units aren't that expensive either.   Up to now I have had these for a few months and it seems to be working okay.


Here's the link


https://www.mr-rcworld.co.uk/shop/variable-speed-controller-/ (https://www.mr-rcworld.co.uk/shop/variable-speed-controller-/)


John
Title: Re: ESC or reversible switch for 1.5v motor
Post by: andyquirot on February 16, 2019, 03:39:04 PM

eBay item number:
223394181307
Title: Re: ESC or reversible switch for 1.5v motor
Post by: pipster on February 16, 2019, 04:09:20 PM
Thanks all - really helpful - I'll investigate each but they all look promising.
Phil
Title: Re: ESC or reversible switch for 1.5v motor
Post by: Allnightin on February 16, 2019, 05:44:54 PM
If available size and weight are limited  you could look at using the Feetech FS90R continuous rotation servo which I have flagged up several times in similar threads here.  One possibility that might appeal is that you can remove a stage or two of the reduction gearing and take the output direct from the servo so that total weight of the whole unit is about 8 grams.  They are also cheap at just over five pounds each:

https://www.rapidonline.com/Feetech-FS90R-360-Continuous-Rotation-Micro-Servo-37-1335?IncVat=1&pdg=pla-338898275481:kwd-338898275481:cmp-757438067:adg-44804851896:crv-207912323492:pid-37-1335:dev-c&gclid=CjwKCAiAhp_jBRAxEiwAXbniXY_CzxhzY-G2sqhpOMjXTbTFbP8wdlPVMS72DhbnLq2ajjGRhZWnQRoCqJcQAvD_BwE
Title: Re: ESC or reversible switch for 1.5v motor
Post by: malcolmfrary on February 17, 2019, 04:15:00 PM
Just do a bit of experimenting and put a resistor in series with the motor to calm it down.  Start with something about twice the measured resistance of the motor.  Yes a bit of power gets wasted, operating a crane is not likely to be the major activity affecting run time, but you can use pretty much any ESC that takes your fancy.
I would be looking at the element from a dead toaster or hair dryer or other form of heater.  Bits cut from such things make excellent precision high power resistors, and they are free.
Title: Re: ESC or reversible switch for 1.5v motor
Post by: andyquirot on February 17, 2019, 06:04:25 PM
They are also a FIRE risk i they get to hot. PUT a fuse in line with it. Power wasted = heat!!!
Title: Re: ESC or reversible switch for 1.5v motor
Post by: malcolmfrary on February 18, 2019, 10:16:29 AM
They are also a FIRE risk i they get to hot. PUT a fuse in line with it. Power wasted = heat!!!
Big enough ones run reasonably cool.  It is only the very small ones (i.e. 2.5W vitreous enamel) being run at their maximum rating that get hot enough to affect their surroundings, and that takes time.  Big ones like the 5/7/10W ceramic blocks have more surface area and stabilize at a much lower temperature.  Once the required value is known, that value inly needs to be bought once.  Crane motors are not likely to be permanently running, so the current limiting resistor does not get time to over-heat, and has plenty of time to cool down.  A length of heating element being run at considerably less than its designed current will not get that hot anyway.  Certainly not as hot as the base current resistors in the venerable Hitec Gold Brick ESCs.
Like I said, the inefficiency is not likely to have a noticable effect on run time, cranes have a very thin duty cycle.
One alternative is to use motors recovered from servos.  Already the right voltage for running off the radio supply, but they do need a "proper" ESC with a deadband so that they can be stopped.
Almost any ESC that uses a relay for reverse is going to control a motor powered by a low voltage, like the ones mentioned by chas and John W E.  The Mr RC World one has a built in soft start/stop which can make things tricky when working a winch.  Overshooting when trying to stop is a PITA.
Title: Re: ESC or reversible switch for 1.5v motor
Post by: John W E on February 18, 2019, 11:31:11 AM

Almost any ESC that uses a relay for reverse is going to control a motor powered by a low voltage, like the ones mentioned by chas and John W E.  The Mr RC World one has a built in soft start/stop which can make things tricky when working a winch.  Overshooting when trying to stop is a PITA
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Hi
the ones from Mr RCWorld   is only soft start, on start up NOT STOP


john

Title: Re: ESC or reversible switch for 1.5v motor
Post by: malcolmfrary on February 19, 2019, 09:44:25 AM
Almost any ESC that uses a relay for reverse is going to control a motor powered by a low voltage, like the ones mentioned by chas and John W E.  The Mr RC World one has a built in soft start/stop which can make things tricky when working a winch.  Overshooting when trying to stop is a PITA
Hi
the ones from Mr RCWorld   is only soft start, on start up NOT STOP


john
I tried using one as a sail winch control - if it wasn't a soft stop, it certainly gave a good impression of one.  Great as a drive motor control, though.