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Old 08-31-2005, 08:01 AM   #1
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new high amp schottky diodes, what do they do?

What exactly do the new larger diodes from the likes of xenon, much more, KO propo speedos and Novak do?

Some are allegedly an equivalent to 8 schottky diodes or something?

50021 - Double Super Shottki Diode for M

'This special schottky diode has the power of eight regular shottki diodes and is recommended for use with low turn motors. It can be used for the MMS3 or other forward only speed controllers.'

So why bother? What’s wrong with a normal schottky diode, what's the benefit?
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Old 09-01-2005, 07:52 AM   #2
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well, this has been posted for 24 hours and no response. it looks like you got your answer.
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Old 09-01-2005, 09:27 AM   #3
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Why bother making and selling them then? aka Speedtechrc & PrecisionRC.

They are obviously made larger and more powerful for some purpose!

I notice Hara runs the xexon racing ones on his car when he ran for HPI and orion

and all Ko Propo VFS-1 ESC type speedos come with a massive black thing identical to the Corally one I mention above.
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Old 09-01-2005, 02:46 PM   #4
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They are obviously made larger and more powerful for some purpose!
they are diodes used for protection. protection from the electricity generated by a turning motor in the off section of the duty cycle of the esc. at least that was the original intent of adding a schottky to our r/c circuits, some years ago. when you get down to what they do, i don't think it is illogical to think that there is a point of diminishing returns. they don't have "powers" like this guy would >>

fyi - alot of these little caps, diodes, and whatnot can be purchased for pennies on the dollar at a place like: www.digikey.com - low esr caps, diodes, filters etc....
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Old 09-01-2005, 03:22 PM   #5
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The bigger Shottki's are made mainly for mod motors where the amp spike when braking may blow a standard shottki. I have seen many pro racers soldier 6 or more shottkis to their motor for extra protection, instead of doing that you can just buy one big one.
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Old 09-01-2005, 03:29 PM   #6
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Originally Posted by pyrosian
The bigger Shottki's are made mainly for mod motors where the amp spike when braking may blow a standard shottki. I have seen many pro racers soldier 6 or more shottkis to their motor for extra protection, instead of doing that you can just buy one big one.
exactly. "newer" larger schottki's just save you from having to stack multiple old ones.

i cant remember ko's reccomendations off the top of my head but it woudl be like "8 old style" "4 newer" or "2 super ultra mega's".

to confuse this the novak pigtail one isnt in the same multiples as ko's. something like ko are 4 and 8 amp, whereas novak is 6....or something like that.
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Old 09-01-2005, 04:39 PM   #7
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Default Fet protection!!!

The diode is there to protect the fets from blowing up.

Reason being that ESC pulses power to the motor. With the motor being an inductive device, when power is cut to the motor, current will still want to flow hence creating a high voltage (aka back EMF) this voltage can be so high that it can kill a fet instantly with the right conditions. But in most cases it will heat the ESC fets up because most fets now have a built in diode to protect against this. But with todays minature ESC using minature fets, this unnecessary heat generated can decrease ESC performance and ultimately destroy an ESC. That is why we use external diodes as close to the motor as possible to take the heat away from the ESC. And diode being able to absorb more current is always wellcome.

On the issue of stacking diodes vs a single one that replaces many. All diode have what is called forward leakage (diodes are like one-way valves but they also leak backwards as well) so stacking diodes together increases this leakage where as using 1 single diode leaks much less. This means less energy loss when you go forward using 1 diode as opposed to using many stacked.
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Old 09-01-2005, 04:43 PM   #8
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Originally Posted by seaball
t

fyi - alot of these little caps, diodes, and whatnot can be purchased for pennies on the dollar at a place like: www.digikey.com - low esr caps, diodes, filters etc....
Does anyone have the specs of the KO, Much More, Xenon or even Novak diodes? The digikey place is neat but theres only about 10000 diodes available there (literally).
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Old 09-01-2005, 05:14 PM   #9
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try looking for a dual rectifying schoktty diode. Thats what the novak part is, just put on a pcb.
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Old 09-02-2005, 08:31 AM   #10
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I think buying it from an RC company will give you peace of mind... After all, how do you know if you have the right one for this kind of application with so many different types to choose from? Give the RC industry a chance! They put so much effort into research and development to find new and suitable products for all RC racers, don't they deserve your support?

Good Luck!
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