High current diode isolation

vette427sbc

vette427sbc

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Been a while since I took an EE class so Im not sure if Im thinking correctly here...
Just to give you some background on what Im trying to do first; I am putting power windows in my car and I have a keyless entry system with an extra channel to control something. I want to be able to roll down both windows from my remote using one relay, and one wire to power both windows. I know this could easily be done with 2 relays, but I am trying to keep my already complex wiring system as simple as possible.
So, I can easily get a diode rated for 6amps @200v. Does this translate to a higher amperage rating at a lower voltage? If I work out an inverse proportion, it comes out to a wildly high amp rating (400A) @12v. Math was and still is never my strong suit so feel free to correct me here.
All I need the diodes to do is keep the window wires independent from each other when Im using the switches in the car. So maybe the little 6A diode is enough? I tend to over build my electronics.
 
NO, the forward rating of the diode is 4 amps.....the Peav INVERSE VOLTAGE rating can vary, but is almost of no meaning for our/your use.....

:flash:
 
Hmm so is there any kind of diode out there that can handle the load of a power window? Or is there some kind of other electrickery that could be done here?
 
vette427sbc said:
Hmm so is there any kind of diode out there that can handle the load of a power window? Or is there some kind of other electrickery that could be done here?
Click to expand...

I think most cars have window motors that are what I would call Be-polar in that the body of the motor is grounded through the metal door, with two connectors going to the p/w switch, one for +12 up, the other for 12 Down.....

I would just run two wires to a single relay, through a couple higher amp diodes.....but they need be much higher than 6 amps forward conduction, something like 30 amp each would be nice.....to a single relay.....that when activated, puts voltage to both DOWN wires to the window motors at once.....
 
mrvette said:
I think most cars have window motors that are what I would call Be-polar in that the body of the motor is grounded through the metal door, with two connectors going to the p/w switch, one for +12 up, the other for 12 Down.....

I would just run two wires to a single relay, through a couple higher amp diodes.....but they need be much higher than 6 amps forward conduction, something like 30 amp each would be nice.....to a single relay.....that when activated, puts voltage to both DOWN wires to the window motors at once.....
Click to expand...

That was the plan all along... finding diodes to handle the current is proving to be a bit difficult
 
vette427sbc said:
mrvette said:
I think most cars have window motors that are what I would call Be-polar in that the body of the motor is grounded through the metal door, with two connectors going to the p/w switch, one for +12 up, the other for 12 Down.....

I would just run two wires to a single relay, through a couple higher amp diodes.....but they need be much higher than 6 amps forward conduction, something like 30 amp each would be nice.....to a single relay.....that when activated, puts voltage to both DOWN wires to the window motors at once.....
Click to expand...

That was the plan all along... finding diodes to handle the current is proving to be a bit difficult
Click to expand...

Ebay, or maybe if you large enough town, local supply house, Jax don't have one, and DC lost all their except ONE that I sadly miss to this day.....

:shocking:.....that you will need to buy will have a stud on one side, typically the +/cathode side, and to the solder tabs go to the relay....

they typically use a heat sink, but in fact for your duty cycle, it's doubtful you will need it, 3 seconds is not much......the start surge is maybe 30 amps, but the run is more like ten, especially in the down direction...

:shocking:
 
I agree, there is a bunch of sellers aon E-Bay that should have what you need. You may have to buy more than you need.
 
Richard454 said:
Ummm..I like the KISS principle- why not something like this?

DPDT relay...

http://compare.ebay.com/like/110880285311?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar
Click to expand...
Exactly.
I think I'm missing something here because I'm still trying to figure out why you need a diode.
With my little electricity/electronic knowledge, the only diode I think you would need in such a situation is one to prevent electric "recoil" when you stop powering a relay. And it only have to match the relay activation amperage, which is tiny, usually a 4004 do the job.
 
Richard454 said:
Ummm..I like the KISS principle- why not something like this?

DPDT relay...

http://compare.ebay.com/like/110880285311?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar
Click to expand...

I didnt even think about a DPDT relay... I like that idea, although would likely need a higher amp rating than the one in the link
:thumbs:

denpo said:
I think I'm missing something here because I'm still trying to figure out why you need a diode.
With my little electricity/electronic knowledge, the only diode I think you would need in such a situation is one to prevent electric "recoil" when you stop powering a relay. And it only have to match the relay activation amperage, which is tiny, usually a 4004 do the job.
Click to expand...

The point of the diodes would be to isolate (in one current flow direction) the two wires that are going to be tied together. Without the diodes, a single wire could not feed both windows without linking them together when the switch is used.

I did find some 10A diodes online that I think I may try out
 
vette427sbc said:
The point of the diodes would be to isolate (in one current flow direction) the two wires that are going to be tied together. Without the diodes, a single wire could not feed both windows without linking them together when the switch is used.
Click to expand...
ok, got it.
 
A principle current limiter for a diode is heat. Since power windows are momentarily used, you can skimp a little on current ratings. If you diode is a little undersized as for current capacity, you can buy a heat sink for you diode. A silicon diode has a half volt drop in the forward current carrying direction.
P, in watts, equals V times I. So for 10 amps, the diode is dissipating (0.5 volts)X(10 lamps) = 5 watts.
 
Look at the amperage of the power window's circuit breaker. I'd pick a diode of the same amperage.
 
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