Schottky Diodes ?

[jakethesnake]

I have an Mtroniks Forwards only ESC. The instructions state that a schottky diode should be used on the motor with forwards only ESC's.

Why is this and will I do any damage if I don't use one ?.

I have the choice of the standard kit 540 or a Yokomo Pro Stock II 27T motor. Car is a TT01 Subaru.

[fastboy]

the didode is there to help protect the speedcontroller from any unwanted electrical noise from the motor,should also help keep the speedo running a little cooler.

it can only be fitted to a motor if you are using a forwards/brake speedcontroller,if your speedcontroller has reverse then you will see lots of smoke or maybe a pop when you try it

make sure the didode is fitted the correct way around (silver band to the positive tab on the motor)

you wont always damage the speedo by not running it but it recommended you use it,i never run without one.

speedos have got so small now that their isnt room in the speedo to fit a diode of that size so now you fit them externally instead.

dave

[smallman28]

quote:

Originally posted by fastboy

the didode is there to help protect the speedcontroller from any unwanted electrical noise from the motor,should also help keep the speedo running a little cooler.

it can only be fitted to a motor if you are using a forwards/brake speedcontroller,if your speedcontroller has reverse then you will see lots of smoke or maybe a pop when you try it

make sure the didode is fitted the correct way around (silver band to the positive tab on the motor)

you wont always damage the speedo by not running it but it recommended you use it,i never run without one.

speedos have got so small now that their isnt room in the speedo to fit a diode of that size so now you fit them externally instead.

dave

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It seesm strange then that the LRP Pro1 ESC I use in my TXT has the facility to remove the reverse function if required yet it says under no circumstances fit a Schottky diode,obviously a bit of trickery going on in there somewhere then!

[GPZ1000RX]

The Schotty also serves to minimise radio interference from the motor.

LRP are being careful with their instructions, if someone were to fit a Schotty (because the instructions didn't say not to!) then forget and re-enable the reverse function, use reverse and cook the ESC then LRP could be liable for the damage. So they just say don't fit one, if you do then you are liable.

I personally would not fit a Schotty to any thing that could, under any circumstance, send reverse voltage to the motor.

[fastboy]

the diode actually helps the fets inside the speedo run a little more cooler,they cancel out any electrical spikes from flowing back into the speedo and possibley damaging the fets..if your speedo is forwards only then use them,if you accidently wire the diode up wrong then all it will do is either pop or smoke until its circuit is broken,it shouldnt damage the speedo(dont ask me how i know ..many yrs of racing, sometimes you make cockups [:I] )

dave

[sosidge]

Sometimes the speed will blow before the diode though... as happened to my GM V6R reverse speedo when I hastily fitted a motor with a schottky on it it already...

[GPZ1000RX]

Been there, done that, bought the tee shirt, eaten the pie! :-)

Luckily (and that is all it was) the diode popped before the ESC.

I wouldn't care to bet my speedo on it tho!

[sosidge]

Yep, I learnt my lesson!

No schottky's are kept on the motors in my pitbox now - I always take them off (imagine the embarassment if I lent a mate a motor - and then his one blew up!).

[jakethesnake]

There isn't a lot of room to solder a diode onto a standard 540 motor. I think I may just run the 540 without a diode. ESC is forwards only so no danger of reversing current.

I have been told that the diode improves the braking performance, is this true ?.

[sosidge]

Yes, it does - but you'll never be going fast enough to need the brakes with a 540!

[jakethesnake]

LOL ! It's got ballraces in it and seems quite fast to me with the standard 540!. Should I put the Yokomo Pro Stock 27T in it then ?. Would that be any faster ?.

[sosidge]

The Yokomo motor wil be faster, yes.