Author Topic: Question Regarding Diodes in Schematic  (Read 8952 times)

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Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #50 on: September 30, 2016, 01:41:57 pm »
holy smokes! it works! I've built up the next step and it works. I know you said to start at the end and work back and I didn't do that, but once I got all the way to the end it did work as expected which after testing out the first half without the second half is not what I expected.  :o

I added two diodes, one capacitor 1uf, two resistors 1k, one 2n2222 transistor and it works perfectly!  Perfectly.

Thank You Sir.
 

Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #51 on: September 30, 2016, 02:57:07 pm »
Alrighty then moving on, it works with the second transistor LED set and it works with a third if I remove one of the resisters from the third set. If I just use an6884 LED driver it works great. So I haven't tried the next frequency yet but what I have noticed is that below 30 Hertz the LEDs Flickr intensely until down to about 5 Hertz then they go off.
 

Online ataradov

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Re: Question Regarding Diodes in Schematic
« Reply #52 on: September 30, 2016, 02:59:27 pm »
So I haven't tried the next frequency yet but what I have noticed is that below 30 Hertz the LEDs Flickr intensely until down to about 5 Hertz then they go off.
As I said, the circuit will require tuning and it would be really hard to debug this without proper equipment. You really need at least a scope and a signal generator.
Alex
 

Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #53 on: September 30, 2016, 03:42:50 pm »
Lol. Well I have an oscilloscope but it's one that I made and it plugs into the computer audio card. It works pretty well but I'm sure not as well as the real deal. I've noticed a little interference from the computer internal components whatever sometimes, but yeah I do not have an oscilloscope yet.
 

Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #54 on: October 05, 2016, 11:58:36 pm »
Ok. So I'm still working on this. For the first three filters I've used electrolytic capacitors. I'm beginning to think I should be using Tantalum. The part used in the schematic is C-EUC0805K. The sizes used are 1uf, 100nF and 10nF.

The circuit is working with electrolytic, but I don't have and can't find 10nF electrolytic. Researching part C-EUC0805K I'm finding that it's a surface mount tantalum.

Is this correct? Should all caps in the project be tantalum?

Thank You,
John

p.s. Ceramic capacitors don't work at all.
« Last Edit: October 06, 2016, 12:01:04 am by bumba000 »
 

Online ataradov

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Re: Question Regarding Diodes in Schematic
« Reply #55 on: October 06, 2016, 02:52:32 am »
The circuit is working with electrolytic, but I don't have and can't find 10nF electrolytic.
That's just way to small to make electrolytic.

I see no reason why ceramic capacitors won't work in this case. That would be something I investigate first.

Alex
 

Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #56 on: October 06, 2016, 02:56:26 am »
Using ceramic capacitors in just one of the three filters makes the other two filters not work. All of the capacitors in the Schematic have a line added to one side making me think that means the negative side which is what I've done using electrolytic where size matches stock.
 

Online ataradov

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Re: Question Regarding Diodes in Schematic
« Reply #57 on: October 06, 2016, 02:59:39 am »
What is the source of your ceramic capacitors? Are you sure they are actually capacitors?

There is no way caps in one filter will affect any other filters, that's why there is a buffer before each filter.
Alex
 

Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #58 on: October 06, 2016, 03:26:40 am »
Sold as, purchased as, look like and taste like capacitors.  8) Heck they even measure up with my handy LCR meter.





Here's what I've got so far. I'm not a fan of the jumpers, but I'm still fine tuning my layout skills and I also don't have my double sided boards yet. I know you can't diagnose a circuit from a picture like this, but...





Here's the bottom

 

Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #59 on: October 06, 2016, 03:29:46 am »
I've just purchased these SMD Tantalum Capacitors in 0.010uF, 0.1uF and 1uf. All for this project. Sure hope they work!!

http://www.ebay.com/itm/Kemet-0-01uF-01-50V-X7R1206-SMD-Tantalum-Capacitor-C1206C103K5RAC-10nF-40pcs-/142128076359?hash=item21177e5647
 

Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #60 on: October 07, 2016, 06:23:04 am »
I'll have ceramic capacitors here tomorrow or the next day that are large enough to use in this project. I have the 10nF and 100nF covered, I just don't have any 1uF ceramics right now... I do have polyester, but they're 100v and none large enough.

Hey, while I'm on this. I've read time and again that capacitor voltage doesn't matter. Just that it needs to be greater than the voltage in the circuit. If I'm running a 5v something I can use a 6.3v or 10v cap, but I can also use 1000v cap. As long as the capacitance value is right for the job, the voltage won't have any negative effects? At all? There is no advantage in this case in using 6.3, 10, or a 1000 other than cost??

Thanks, John
 

Online ataradov

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Re: Question Regarding Diodes in Schematic
« Reply #61 on: October 07, 2016, 07:07:25 am »
As long as the capacitance value is right for the job, the voltage won't have any negative effects?
That is correct in many cases.

At all?
Well, capacitors have many parameters apart from the capacitance value and rated voltage. ESR would be one of those parameters.

But for this project, none of that should matter and any capacitors should work.
Alex
 
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Offline timb

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Re: Question Regarding Diodes in Schematic
« Reply #62 on: October 07, 2016, 07:28:20 am »
I'll have ceramic capacitors here tomorrow or the next day that are large enough to use in this project. I have the 10nF and 100nF covered, I just don't have any 1uF ceramics right now... I do have polyester, but they're 100v and none large enough.

Hey, while I'm on this. I've read time and again that capacitor voltage doesn't matter. Just that it needs to be greater than the voltage in the circuit. If I'm running a 5v something I can use a 6.3v or 10v cap, but I can also use 1000v cap. As long as the capacitance value is right for the job, the voltage won't have any negative effects? At all? There is no advantage in this case in using 6.3, 10, or a 1000 other than cost??

Thanks, John

Sort of! It depends on the type of capacitor...

Short Answer: As long as the maximum voltage you place across the capacitor is lower than the capacitor's rating, it won't blow up or anything. The voltage rating is literally the working voltage of the capacitor. (So, like you said, you can put 5V across a 6.3, 10 or 1000V capacitor and you're fine; however you shouldn't put 1000V across a 6.3V cap!)

Long Answer: Depending on the dielectric of the capacitor, what you're using it for and the temperature you'll be using it at, you may need to derate the value.

Aluminum Electrolytic: These are generally used for bulk storage and smoothing ripple. As a rule, the higher the voltage rating of this type of cap, the larger the ripple current it can tolerate. This shouldn't be something you have to worry about unless you're making a huge linear power supply or something.

The voltage rating of AE caps is also fairly conservative; you can generally go over the rated voltage without trouble (assuming you're using a brand name cap and not a questionable off-brand). If you do exceed the voltage rating, you'll lose some capacitance (e.g., if you run a 10uF 6.3V cap at 9V, you might only get 8uF of capacitance).


Ceramic: These are generally used for decoupling. They tend to be very temperature sensitive, and quickly lose capacitance as temperature changes when run near their rated voltage. Say you've got a board inside an enclosure that gets up to ~85c. You've got a bunch of 1uF and 0.1uF 6.3V Z5V ceramic caps on the board to decouple the 5V rail. Well, because you're running them near the rated voltage and at a temperature above ambient, the capacitance could be down by as much as 80% (meaning that 1uF cap is really a 0.2uF cap)!

The way to avoid this is to use better dielectrics like X7R (which will only lose 15% of its rated capacitance over a temperature range of -55 to 125c). As a rule you should also derate the voltage, I like to make sure my ceramic caps are rated for at least double the voltage they'll see (so, a 10V cap if I'm decoupling a 5V rail); this also helps to lessen the loss of capacitance over temperature.

MLCC style caps should be avoided anywhere they'd be exposed to frequencies in the audio range. Due to the nature of their construction, they can actually resonate and "sing"! The inverse is also true, so additionally they should be avoided in equipment that will be exposed to regular vibration or shock, as this can cause the capacitor to actually generate a voltage on its own! (This is called microphonics and I believe Dave did a video on this, where he taps an SMD cap and shows the voltage on a scope.)


Tantalum: These have similar uses to AE caps. You absolutely *must* obey the voltage rating of tantalum caps! They have a nasty habit of literally exploding (violently, too) when their voltage rating is exceeded. Tantalum is also a conflict mineral, which is sort of interesting from a philosophical point of view.


Okay. So that's the long version of the basics. :)
Any sufficiently advanced technology is indistinguishable from magic; e.g., Cheez Whiz, Hot Dogs and RF.
 
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Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #63 on: October 07, 2016, 11:03:00 am »
Thank you very much!
 

Offline bumba000

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Re: Question Regarding Diodes in Schematic
« Reply #64 on: October 11, 2016, 03:26:42 am »
Okay folks. I have the multilayer ceramic caps, I've re-re-built using them and it works. It works very well. Very Well. I did have another problem too. Each filter (seems to me anyways) is a voltage divider then two caps in parallel one having a resistor after it. I had placed the divide R2 after the two parallel caps. This is where the re-re comes in...

Hey I'm super green, what else can I say but thank you guys.
 


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