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ArcticMyst Security by Avery

The E-drive (V3) + PDF

gillza

gillza

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Jared,

could you shed some light on it? I haven't received the package yet so I can't do any testing, but I'm curious as to why this might happen.

Thank you
 





Hiemal

Hiemal

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Well, I'll reveal the process how to figure current for it.

In the op amp I'm using there is a 1k ohm resistor. Literally INSIDE of it, so it removes the need for an external one.

Now, anyway, to figure gain, there is another resistor that is placed on the op amp's output, in series with the potentiometer.

Thr resistor should be 12k ohms. Meaning when the pot is set to zero, or around it, the gain should be 12.

The voltage reference of the IC is 500 mV. To figure sense voltage divide 500 by 12.

500 / 12 is 41.666 mV of sense voltage.

Now I = E/R, correct?

So, 0.041.66 / 0.015 ohms (that's the sense resistor's value!) and you get a max output of 2.77 amps, which allows for some leeway in terms of the pots ACTUAL value.

If the resistor was 6k, then it would just be a higher current limit set by the pot. Somewhere around 3-4 amps (the driver can't do 3-4 amps though! Max is 2.3-2.4 amps!)

I'm talking to Yob about it to see what's up.
 
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gillza

gillza

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I have received my two drivers.

One of the drivers was heatsinked by soldering a piece of metal on to the powerpad. This used to be a BB for my old slingshot. Unfortunately I did not have a piece of copper...
20121208_001.jpg


20121208_001s.jpg


20121208_003s.jpg


20121208_006.jpg


20121208_005.jpg


Pardon my dry and dirty fingers.

The heatsinked driver was tested in the buck mode (two lithium cells) at 4 diode settings on the test load resulting in the total load of 5.5V at maximum.

When just connected the driver output is:

20121208_007b.jpg


The maximum output that I got:
20121208_008b.jpg


At 2.27A the heatsink of the driver became VERY HOT, very fast, so a larger body of metal would be necessary for longer operation.
 
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Hiemal

Hiemal

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Okay, so Yob had sent me back his driver for me to poke it a bit, to figure out why it wasn't outputting the necessary current.

Reason it wasn't was most likely due to lack of heatsinking. When I connected it up to my oscilloscope, I found that it WAS starting out at 2.25 amps, but then dropped quickly as it began to overheat. So, if you want 2.25 amps, make sure you heatsink it well, otherwise you won't get the full output you desire!
 
Hiemal

Hiemal

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Okay everyone; as you are all fully aware, the E-drive has... Gone kind of silent for the past few months or so.

Well, I'm happy to tell you all that it is NOT dead. I can promise that. There was a slight lull in it but when they are going to be made again, it won't be in small 2-5 numbers.

Expect 20-25 per round or so, sometimes higher an sometimes lower. Another little feature I'm adding is taking away the pots that were on the previous boards, and using nicer black ones that have internal stops. That way it doesn't keep spinning!

As a result of the cost of labor for getting the boards made in larger quantities, I have to raise the price by $2.

When they come out for sale again, expect to see them for $17.99, in larger amounts. :)
 
Meatball

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I've been wondering what happened to this one.

Its the most promising solution to what everyone wants.
 
Meatball

Meatball

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Basically, the conclusion was that there were not enough made and distributed and reviewed. That was the final step.

I thought he was planning on a large production run or something. He just needs to get them out there.
 
benmwv

benmwv

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Oh, I hadnt seen that thread.

Hopefully jared just got busy with school and will be coming back to it not letting it die.
 
ARG

ARG

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They would be used a lot more if they went open source.
That way people could check the design as well.
 
benmwv

benmwv

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ARG said:
They would be used a lot more if they went open source.
That way people could check the design as well.
Click to expand...

Definitely! I am always in support of more open source drivers.

Has anybody emailed him? He might not be getting the notifications. I should have his email somewhere.
 
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