Schottky diode??
 

I've just bought an MSonik Tempo 15 ESC to use with my RS545 motor and 7.2v 1800mAH batt.

Now the installation instructions say...

"...you MUST run an 8A Schottky Diode on the motor"

What does that mean? It also says I need to put 0.1 microF caps from the motor terminals to the can, which I understand.

Where do I put the Schottky and which way round?

RE: Schottky diode??
 

a schottky diode is a diode inserted in the motor circuit bridging the +and - lines to the motor.

The polarity of the diode must be correct or the motor won't run at all. (I happen to have an ESC with the diode wired n in my lap...;)) The silver band goes toward the + line.

My ESC is a GP C-30, the diode (came with a motor that doesn't require this large an ESC...) is an "SR506 JGD" (what that means.. I have no clue... its going to tell the current and voltage rating ot the diode tosomeone who knows how to read the code.)

What the diode actually does is it aids in recovering power stored in the capacitor bridging the + and - leads at the motor. If you don't use the diode in my motor circuit you get 40% less motor run time. You also get less maximum rpm.

The Capacitors convert RF noise potential of the sparking at the motor commutator into stored energy... the manner in which this is done reduces the spark size. (run an electric drive motor in a drk room without the capacitors... then again with the capacitors. The difference in visible sparks is huge.) Without the diode, the majority of the stored energy is "wasted" combating the next spark pulse.... with the diode it s ported back to the motor and used to make the motor run faster.

RE: Schottky diode??
 

So I should end up with this (see image).

My motor has a red dot next to one of its tags, I assume that's the positive one(?)

RE: Schottky diode??
 

There are specs for the SR 506 diode at the link below:
http://www.chipdocs.com/pndecoder/da...06.html?ReR=GG
The SR 802 thru 806 will handle 8 amps. (20 volts for the 802, 60 volts for 806)
Hope this helps

RE: Schottky diode??
 

If the motor is not geared... yes the red dot gets the positive lead, and the picture s correct.... for the diode...

The setup you have will work... but you should have 3 capacitors. One from each wire to the morot case... and one between the wires, parallel to the diode. Sometimes the - pole of the motor is grounded to the "can" and inthat case... you may as well just have one capacitor from + to the can (or the - lead) because the one from - to can is useless. (and the other 2 would be in parallel)

Mine was in a geared drive setup and the red dot got the negative lead. (motor "neutrally timed" so running "backward" was not a problem.)

RE: Schottky diode??
 

I think your connection drawaing is correct.
The only function of the diode and capacitors are to minimize the interference created by the motor into the power suplly lines, which could affect the electronics on board (receiver).
This interference is because the inductive behavior of the motor.
There are no gain in power because the diode or capacitor.
Schottky diode are used because their high speed of commutation, comparing to other regular diodes.

Nilo

RE: Schottky diode??
 

Thanks for the help guys, this is very helpful.

I tried to obtain some schottkys and caps today but only managed a handful of caps. The diodes seem to be very difficult to get hold of in Derby. I tried a few places here including Maplin's (UK equivalent of Radioshack) and they only had 3 Amp ones.

Curses!

My instructions for the ESC seem quite adamant that the schottky should be there. It gives no mention of the 3rd cap (but I'll put one in anyway).

Does anyone know a mail-order place in the UK that supplies a GOOD range of electronic components? Maplin's blow. :)

RE: Schottky diode??
 

For mor info on the Shottky diod... see the electrics forum.

Contrary to nilo's post... the diode has nothing to do with interference. (never used them with any ESC or with the resistor type 3-speed controllers until this newest electric drive came with one.)

And I have tried the motor with the diode and without... 20% more rpm with the diode... and 30% longer motor runs at full throttle. So its got to be doing something to aid the power situation. (and this is with the ESC... or just hot-wiring direct to the motor with a 10 amp 12 volt rated switch.... same result.)

RE: Schottky diode??
 

Every inductive load under variable current generates spikes and will try to keep the current constant.
The way the inductive load do that is by creating an opositive voltage to what had created the initial current flow.
This voltage is high because the impedance is high and can damage electronics devices conected to it.
Interference is being trasmitted by air as electromagnetic waves and on the power suplly wires.

Don't believe it? Plug an osciloscope and watch!;)

Nilo

RE: Schottky diode??
 

That's what the capacitors are for... They clean up the nterference. The diode has essentially no effect on the interference.