Castle Creations UBEC Test

[BrianG]

And I thought I was the only person here that didn't...

[jhautz]

Originally Posted by BrianG

And I thought I was the only person here that didn't...

You are the only one who doesnt have one silly.... I thought they were as common as toasters.

I'd let you borrow mine, but its in the shop... Yea, Yea, thats it.... Its in the shop.

[johnrobholmes]

I would love to see the reaction time of the BEC to input variations. Sampling rate is supposed to be really high for the calibration (10kz or more I think), but I have heard of guys having problems when the input power fluctuates wildly. My guess is that the output changes enough to mess up some radios, or maybe it causes a lot more noise. Never had the problem personally, but I would love to see some data. I would love to have a Silly scope at all right now.


Only one way to test Pats claims Brian, give it a shot! He was probably conservative. I ran mine past 220f and they didn't show any signs of lag or reduction in amp output. Maybe you could shoot for the same.

[lincpimp]

Originally Posted by jhautz

You are the only one who doesnt have one silly.... I thought they were as common as toasters.

I'd let you borrow mine, but its in the shop... Yea, Yea, thats it.... Its in the shop.

Betcha don't have a cordless toaster! I do, and I made it myself.

[BrianG]

A cordless toaster eh? What's your toast time (runtime)?

JRH: I attempted to test output variance with fluctuating input voltage. I hooked the output of my 14.8v PS to an external linear regulator (with pass transistor). I used an LM7812 and set it up in adjustment mode. Then, I put the adjustment circuit on a rotary switch so it alternated between 12v and ~14v as fast as I rotated the knob. This was the only way I could think of simulating a quickly changing input voltage. I used my 2.5 ohm resistor as a load to pull ~2A from the BEC.

The output did change, but by just 20-30mV. However, I'm not sure my linear regulator setup was able to change voltage as fast as needed. Even still, I'm at the mercy of my voltmeter sampling rate. Soooo, I hooked the BEC output to the same load and a Spektrum receiver/servo and tried it again to see if the receiver would glitch. Nothing; it worked just fine.

Do you know if the people seeing the problem were using ESC braking? Depending on the setup, the back-EMF from hard braking could be generating voltage spikes exceeding the BECs input rating. Something to think about. Most other BECs on the market are rated up to 35-40v, so there is more headroom if this is the case.

[lincpimp]

Actually I just cut the cord off a regular toaster = cordless now

It was a big joke, and I was going to sell them, via ebay most likely. Imagine all of the benefits of a cordless toaster - completely safe around water, children and forks. Completely portable, take it anywhere. Only drawback is that it would not toast bread, a minor inconvenience.

Just like to share my experience with this BEC. I dont have a 100% understanding on these BEC. But I know that heat kill mine...along with the $100 servo. I mounted mine right next to my Mamba, I guess the heat from the mamba transferred onto the BEC. Next thing i know the input and output voltages were the same. And since I was running a 5s A123 cells (17.6volt nominal), it was enought to kill the servo and the fans that was running of it. That servo smells like burn toast now.

[BrianG]

Yeah, I read over at the Castle site that this could happen (output v = input v). I'm surprised your receiver made it ok.

IMO, knowing about this issue, Castle should've incorporated "crowbar protection" - which has the effect of dropping a crowbar across the power line. In the event the output rises too high (~10v to allow for the full 9v range) a device would short the output. This would obviously be "bad", but the circuit is bad anyway to allow the full voltage through. Of course, shorting the output would burn up the BEC and/or the small wires, but sure is better than burning up expensive servos/rx/fans/etc. I think an SCR device and a couple of support components would be all thats needed.

A little explanation: http://en.wikibooks.org/wiki/Practic...rowbar_circuit

You might argue that better circuits could be created to deal with this, which is true, but this would be an add-on part...

yeah, I was very surprise that my receiver survive it. I guess the receiver's own internal BEC might have protected it. I cant remember the model # of the reciever, but its the one that come with the spectrum DX3R.