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FrozenGate by Avery

FREE DIY open source BOOST driver!!! Tested & working!!

Ok, I will be uploading in a few. I was able to successfully remove the caps and put on new ones and plug it up and get .480 amps again. But the scope readings seem quite different. Let me upload.

UPDATE: Here is what I did...

First, I re-scoped the original driver to make sure I had a baseline to work from and then I tried to re-create the exact same thing after I had removed the 10uF caps and replaced them with the 22uF caps.

EDIT: THESE CAPACITORS WERE INCORRECTLY LABELED! THEY ARE ACTUALLY 2.2uF CAPACITORS, WHICH TOTALLY CHANGES A GREAT DEAL ABOUT THIS TEST. ALLIED ELECTRONICS HAD THEM LISTED WRONG IN THEIR CATALOG. So I look like a dummy, I have a hundred dollars worth of capacitors that are wrong by a factor of 10 and have even sent these out to some people to use in their drivers. Even stranger, they seem to work ok?!?

So... Please consider that any caps labeled as 22uF in this thread are actually 2.2uF!


Untitled by tsteele93, on Flickr

I used a heat gun to remove the 10uF capacitors and then put the 22uF caps in place and used the heat gun to replace them. It went surprisingly smoothly.


Untitled by tsteele93, on Flickr

Foulmist asked me to try scoping in AC mode so I started with that. I followed the instructions using the PEAK mode and got this with the 10uF capacitors.


1x probe, 478mA driver, 10uF caps, AC, running by tsteele93, on Flickr

The same reading with 22uF capacitors resulted in a completely different looking waveform.


Untitled by tsteele93, on Flickr

I even tried it using SAMPLE MODE instead of PEAK MODE to see what was going on.


Untitled by tsteele93, on Flickr

Keep in mind though, these are with 1x on the probe and that seems to limit the scope to a 7Mhz max and could result in incorrect readings.


Oscilloscope Aliasing by tsteele93, on Flickr


Aliasing Frequencies by tsteele93, on Flickr


Probe Attenuation by tsteele93, on Flickr

So I did the same thing with the scope and probe set to 10x...

Here is the running AC waveform with the 10uF capacitor:


Untitled by tsteele93, on Flickr

And here is the running AC waveform with the 22uF capacitor:


Untitled by tsteele93, on Flickr

Next I looked at the same scenario with DC instead of AC.

Here is the 10uF capacitor with a 1x probe:


1x probe, 478mA driver, 10uF caps, DC, running by tsteele93, on Flickr

And here is the 22uF capacitor with the 1x probe:


1x Probe, 478mA, 22uF, DC, running by tsteele93, on Flickr

Now the same two waveforms with the 10x probe, so the first one is the DC waveform with the 10x probe and 10uF capacitor:


10x probe, 478mA driver, 10uF caps, DC, running by tsteele93, on Flickr

And now the DC waveform with 10x probe and 22uF capacitor:


10x Probe, 478mA, 22uF, DC, running by tsteele93, on Flickr

I'm going to post this and then add some more captures of startup spikes next.
 
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I will let you guys try to decipher what is going on while the driver is running in the scenarios above. At first glance to me, it looks like a much larger ripple with the 10uF caps - but I'll look at them later - for now I am going to try and upload some more waveforms.

Next I have some startup captures...

This is 10uF with the probe set at 1x with an AC capture:


1x probe, 478mA driver, 10uF caps, AC, single (startup) by tsteele93, on Flickr

Here is 22uF with the probe set at 1x with an AC capture:


1x Probe, 478mA, 22uF, AC, single (startup) by tsteele93, on Flickr

Here are the same two captures at 10X...

This is 10uF with the probe set at 10x with AC capture:


10x probe, 478mA driver, 10uF caps, AC, single (startup) by tsteele93, on Flickr

This is 22uF with the probe set at 10x with AC capture:


10x Probe, 478mA, 22uF, DC, single (startup) by tsteele93, on Flickr

Next I will do DC startup waveforms.
 
There is no spike above the set current with the 22uF caps. Great!

Also the ripple is reduced significantly! I knew this was the main issue with the drivers running with 10uF caps.

Good job Tom :beer:
 
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Now the DC startup waveforms...

Starting with the 1x probe, 10uF caps and DC waveform:


1x probe, 478mA driver, 10uF caps, DC, single (startup) by tsteele93, on Flickr

Compared to the 1x probe, 22uF caps and DC waveform:


1x Probe, 478mA, 22uF, DC, startup by tsteele93, on Flickr

Now the same thing with 10x probes:

10x probe, 10uF caps and DC waveform:


10x probe, 478mA driver, 10uF caps, DC, single (startup) (1) by tsteele93, on Flickr

10x probe, 22uF caps and DC waveform:


10x Probe, 478mA, 22uF, DC, single (startup) by tsteele93, on Flickr

I have a few more waveforms scattere around in the folders and collections on Flickr - feel free to nose around in there. I didn't post more for fear of confusing things. I do have a couple of running MEASURE waveforms I will post though - but I wanted to try and do direct comparisons where possible.

:beer:
 
Finally, here are a few waveforms in the MEASURE mode:


10x Probe, 478mA, 22uF, DC, running (measure) by tsteele93, on Flickr


10x Probe, 478mA, 22uF, DC, running (measure) by tsteele93, on Flickr

And another of the 22uF caps running in DC mode...


10x Probe, 478mA, 22uF, DC, running by tsteele93, on Flickr

And another of the 22uF caps running in AC mode...


10x Probe, 478mA, 22uF, AC, running by tsteele93, on Flickr

I may be starting to repeat some of these - damn you flickr! - but I also thing that by putting different waveforms side by side, it may tell a different story too.
 
Looks like the 22uf caps have completely removed the startup spike.

Did you change ALL 3 or just the output? I dont think I caught that part.

Very helpful comparison ;)
 
benmwv said:
Looks like the 22uf caps have completely removed the startup spike.

Did you change ALL 3 or just the output? I dont think I caught that part.

Very helpful comparison ;)
Click to expand...

All three, the middle one was the trickiest of the bunch. But the two outside ones were pretty easy.

:beer:
 
Yup! That's what would do it. That start-up spike on the 10uF photo looks like a 700mA spike if I am reading your scales properly... which would certainly kill most 12xs in a microsecond, those sensitive bastards!

Anyway, I am confident in saying this is the root of the issue. So 22uF caps it is, then?

Also - Tom - I'd like to talk to you about doing some testing for me, if you'd be interested!
 
Wolfman29 said:
Yup! That's what would do it. That start-up spike on the 10uF photo looks like a 700mA spike if I am reading your scales properly... which would certainly kill most 12xs in a microsecond, those sensitive bastards!

Anyway, I am confident in saying this is the root of the issue. So 22uF caps it is, then?

Also - Tom - I'd like to talk to you about doing some testing for me, if you'd be interested!
Click to expand...

Wow, you'd trust me after this? :D I sure do feel like I still have a ton to learn about testing with scopes, but I'd be happy to help. And I've dug out a few of my old books from college and I'm going to try and bone up on using the scope.

So sure, what did you have in mind? I'll work for cheap drivers. ;)
 
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Sure, why the hell not? Better scoping images that I can get. And with buck drivers, you have to be really careful of spikes ;)

Basically, all I would need from you is a few images of each type: one on start-up, like you have here in wonderful high-res, and one for steady-state operation!

And I would certainly get ya cheap drivers! :D
 
Sounds great! You can PM me with details of what you want to do.

Tomas was wanting me to get the AC coupling versions of the readout and I just found a nice summary of that on the Tek site - just thought that I would share for those of you still learning scopes like me...

Tek said:
Input Coupling

Coupling refers to the method used to connect an electrical
signal from one circuit to another. In this case, the input
coupling is the connection from your test circuit to the
oscilloscope. The coupling can be set to DC, AC, or ground.
DC coupling shows all of an input signal. AC coupling blocks
the DC component of a signal so that you see the waveform
centered around zero volts. Figure 21 illustrates this difference.
The AC coupling setting is useful when the entire signal
(alternating current + direct current) is too large for the volts/
div setting.

The ground setting disconnects the input signal from the
vertical system, which lets you see where zero volts is located
on the screen. With grounded input coupling and auto trigger
mode, you see a horizontal line on the screen that represents
zero volts. Switching from DC to ground and back again is a
handy way of measuring signal voltage levels with respect to
ground.
Click to expand...


AC coupling by tsteele93, on Flickr
 
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I'm looking at getting myself a scope, but if it doesn't work out I might need to make a similar deal with you Tom!
 
Lol! I'll rent my scope out cheap! I actually bid on another one today and was gonna sell this one if I got it - but it went higher than I wanted. I was looking at getting my output to a PC, and this one requires a TDS2CMAX Module to do that and they are going for $150+ which is STUPID. So I was thinking of getting a newer scope with a USB and just selling this one.

I may still do that and if I do, I'll probably offer this one for a good deal here on the forum. I'd really like to have output to a PC and be able to use the software.
 
This is great Tom. It's nice to be able to see the spike diference time to change some caps I guess..
 
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