lk

[tamiya monkey]

lm

[tamiya monkey]

i have found some schottky diodes on farnell and was woundering if they are the correct type, i have posted in my showroom if anyone can assist with advice

[tamiya monkey]

http://www.tamiyaclub.com/showroom_model.a...=32476&sid=3622

my showroom

[raemin]

Just have a look at tekin website regarding shotcky diodes. These are not mandatory on your ESC and should be used if you experience glitchering caused by backward current. It should be reminded that shotcky diodes :

- are not compatible with reverse ESC

- do absorb a little bit of the current sent to the motor

Hence if you don't need them don't use them...

[raemin]

By the way, these seems to be the correct diodes...

[terry.sc]

Quote from Novaks website

quote:

A Schottky diode is a special type of diode with a very low forward-voltage drop. When current flows through a diode, it has some internal resistance to that current flow, which causes a small voltage drop across the diode terminals. A normal diode has between 0.7-1.7 volt drops, while a Schottky diode voltage drop is between approximately 0.15-0.45 – this lower voltage drop translates into higher system efficiency.

At partial throttle, a speed control switches the battery power to full-on and full-off at varying duty cycles. The ratio of the duty cycle determines the throttle setting – for example: 50% on to 50% off is 1/2 throttle. The Schottky diode is used to carrying the re-circulating current from the motor during the 'off-time' while the speed control is at partial throttle.

Similarly, the motor in a car is like a big inductor. During the off-time at partial throttle, the motor will not allow the current to just stop. Instead, the voltage across the motor will reverse, and current will flow through the Schottky diode. If no diode is present, the current will flow through a parasitic diode built into the brake transistors. The current flows through the Schottky diode before it will flow through the brake transistor because the forward voltage drop of a Schottky diode is less than the brake transistor diode (this is why Schottky diodes are used and not other types of power diodes).

For the highest efficiency, during the off-time while the motor continues to flow current, the voltage should ideally be as close to zero as possible. One reason Novak uses an external Schottky diode is because the closer the diode is to the motor, the lower the voltage drop during this period. This is due to the voltage drop through the wires back to the speed control. This will also reduce some radio noise due to the current spike not having to travel a long distance.

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Schottky diodes are used to improve the life and performance of the ESC. It helps reduce the amount of high voltage spikes from the motor that could reach your speed control. This emf feedback occurs when running on partial throttle as well as when braking. Without a Schottky diode when you brake quite large high frequency voltage spikes are generated by the motor which go back down the wires to the ESC. These voltage spikes can damage the brake FETs.

If the manufacturer recommends a schottky diode then fit one, if it gets damaged they will know a diode has not been used. The manufacturers are now recommending fitting 2 diodes on high power low wind motors as one is not powerful enough. A diode should be provided with the ESC. Solder it between the 2 motor terminals, the end with the silver stripe should be connected to the positive side.