Author Topic: EEVblog #568 - Solderless Breadboard Capacitance  (Read 26184 times)

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Offline w2aew

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #25 on: January 15, 2014, 09:31:45 pm »
If u can't use breadboard for switch old power supplies how do you prototype them first time

Have you seen my video on prototype construction techniques?  Several of these techniques could be used to build a prototype of a switch-mode power supply. 

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Online FrankBuss

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #26 on: January 15, 2014, 09:58:52 pm »
This could be useful is you want to test different low value capacitors:



Looks like it is pretty linear, the wires don't matter much. And I guess it will be pretty stable as well, no microphonic or other effects as known with cheap X7R capacitors, and very temperature stable.
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Offline NANDBlog

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #27 on: January 15, 2014, 10:19:23 pm »
If u can't use breadboard for switch old power supplies how do you prototype them first time
You dont. The layout is an essential part of an SMPS. If you design one, chances there wont be any through hole parts, and the IC will be one of the leadless DFN or similar package. The only way to prototype it is to run a smaller board containing only the layout. Then you can try multiple parts.
But right now I'm only talking about 1-10W POL SMPS
 

Offline KJDS

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #28 on: January 15, 2014, 10:31:46 pm »
If u can't use breadboard for switch old power supplies how do you prototype them first time
You dont. The layout is an essential part of an SMPS. If you design one, chances there wont be any through hole parts, and the IC will be one of the leadless DFN or similar package. The only way to prototype it is to run a smaller board containing only the layout. Then you can try multiple parts.
But right now I'm only talking about 1-10W POL SMPS

Most of the little ones have applications boards available from the manufacturers.

Offline JoannaK

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #29 on: January 15, 2014, 11:05:06 pm »
If u can't use breadboard for switch old power supplies how do you prototype them first time
You dont. The layout is an essential part of an SMPS. If you design one, chances there wont be any through hole parts, and the IC will be one of the leadless DFN or similar package. The only way to prototype it is to run a smaller board containing only the layout. Then you can try multiple parts.
But right now I'm only talking about 1-10W POL SMPS

Most of the little ones have applications boards available from the manufacturers.

And one can puchase entire prebiuld SMPS module from chinashop at the price of parts or lower..

Another option are those factory potted switch modules. I rememeber seeing 78xx plug in replacement switchers with merely few bucks (5?) in singles quantity.
 

Offline JackOfVA

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #30 on: January 15, 2014, 11:17:05 pm »
For low capacitance prototyping, you might consider the island pad approach using a diamond tipped core drill - it's described at my web site page http://www.cliftonlaboratories.com/Prototyping.htm

Measured capacitance is less than 1 pF and I've built circuits with that up into the 100 MHz range and above.

Or the push-in Teflon pin approach - it's illustrated towards the bottom of that page. That yields low C and very high leakage resistance for those circuits where G-ohm leakage is needed.

Jack

 

Offline Maxlor

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #31 on: January 15, 2014, 11:22:46 pm »
Even 100KHz is going to cause trouble due to the loop inductances, capacitance, and general dickiness.
(emphasis mine)

I love that expression of yours. I suggest we should make it the official measure of reliability of a given design. The unit we measure would be the Dave of course! And the higher the unit value, the higher the amount of dickiness, so I propose 1 Dave => it works on the first attempt, 10 Daves => it takes 10 attempts to get it working, and so on  ^-^  :bullshit:  :-DD
 

Offline zucca

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #32 on: January 16, 2014, 03:23:41 pm »
Have you seen my video on prototype construction techniques?

Amazing, just thank you. Keep going on I suscribed to your channel.

This could be useful is you want to test different low value capacitors

Nice idea! Why I did not think about that in the past?
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Offline electronics man

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #33 on: January 16, 2014, 06:54:56 pm »
So, does anyone know the function of the gutter/divider in the middle? They all have it, without fail.

the gutter width is set to DIP distance of course, but there is no reason to make a gutter for DIP IC. Some more unused contacts would be OK as well. And sometimes I wish I could span a 5mm (2x2.54 pitch) cap over the gutter witch is not possible.

The only reason I can think of a need for a gutter is if you have some component that has a dangly bit under the pins, but I have never seen such a device. Or more imaginative, to drain the magic goo that escapes together with the magic smoke.

So, anyknown knows why the gutter is there?


Well I have had to use heat sinks whith large fat legs on them that fits perfectly in that bit I have also have used rotary encoders whith pins in the middle for strength that fits in the bit in the middle so yes it does have a pepose
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Offline georges80

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Re: EEVblog #568 - Solderless Breadboard Capacitance
« Reply #34 on: January 16, 2014, 07:28:19 pm »
With the cost of proto PCB places and most 'modern' circuitry being SMT I haven't used one of those solderless breadboard units for well over 20 years and don't own one here in the US. I know there's one back in oz in my parents garage (where all my electronics junk ended up) from my 'youth'.

All my prototyping since being here (digital) was wirewrap and that would happily run into the 20MHz range with careful placement of the wire runs (to prevent crosstalk and other nasties).

Now everything I do is surface mount and for <$100 I can get a bunch of different protos on one panel in <1 week. Seems totally pointless to not go straight to PCB these days and not have to fight with layout issues which is important in my case since all my designs are uC based and/or typically have reasonably high current switchers.

For just daydreaming, it's easier to just throw the circuit up on LT spice to verify that it should be 'close' to working the way you think and then put it on a pcb proto run.

I sometimes have little designs  that I think would be neat to try out, so I just design them up, do the PCB layout and add it to a panel. Once I have enough on a panel (maybe every month or two) I'll send the panel in to one of the PCB proto places (that doesn't charge a premium for a panelised board) and then I have a bunch of neato little things to build/test for a few weeks. I often put programming adapters for the AVR chips I use on the panel (for the 6 pins ISP header and the mating pogo pins for the PCB layout under test) and also put test adapters (again with pogo pins). This means I can have designs that don't require the 3 x 2 ISP but can have the pins spread all over the board where it makes sense from a routing perspective (most of my boards are relatively small/tight and 2 layer).

cheers,
george.
 


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