Model Boat Mayhem

Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: robs on April 03, 2012, 01:26:19 am

Title: motor suppression
Post by: robs on April 03, 2012, 01:26:19 am
Hi, how can I calculate the correct value of suppressor for an electric motor? I have a salvaged 9.6v motor from a rechargeable vacuum cleaner, the only info on the motor is 9.6v, 21000rpm and BRS-540S6528. I presume that is a 540 size motor but apart from that I am in the dark. Any help would be gratefully appreciated. Cheers, Robs
Title: Re: motor suppression
Post by: ACTion on April 03, 2012, 07:52:40 am
Don't bother, because it's not critical. Either a 0.1uF or 0.22uF will do across the brushes. Make sure it's a ceramic type (NOT an electrolytic) and that the voltage is sensible i.e. at least 50v working. If you are using a 2.4GHz radio then suppression is not strictly necessary, although others may be using VHF radios nearby which might be affected by a "noisy" motor.
DM
Title: Re: motor suppression
Post by: andrewh on April 03, 2012, 08:32:10 am
Robs

What the man says! :}  No calculation involved - just fit capacitors

 <<9.6v, 21000rpm and BRS-540S6528>>  You have most of the information you need right there!
It is wound for endless life at 9.6V (is there Really an 8-cell vacuum cleaner?) so it will have an interesting life at 12V and will run at much more for as long as you need in a boat

The frame is a 540, which means it is 54mm rotor armature length (equivalent to a speed 500 in size)
  S6528 is the makers code for the way it is wound, what wire etc.  If it is from a vacuum this is a very low torque, high speed application so it will be 3-pole and probably quite a beefy wire and few turns (to give the high speed)
The case will also say a makers name or logo, Mabuchi,, Johnson or similar - you might be able to find the exact model on their website - especially if it is Mabuchi

Useful motor if you want to run it on 7.2 to 12V, possibly more - what are you aiming to power with it?  Would probably be good with gears
hope this helps
andrew
 
Title: Re: motor suppression
Post by: dodgy geezer on April 23, 2012, 01:43:19 pm
If you have the rest of the cleaner you will find the relevant filter unit on the electronics somewhere. I'm surprised that the motor didn't already come with capacitors attached - they need to be attached close to the motor brushes....