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Arduino Mega Proto Screwshield PCB, Part 2 (OMG on the Screw Blocks)

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David Ashton
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Re: Tasty terminal blocks
David Ashton   1/21/2014 2:41:14 PM
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@Max...I have thought of doing that myself, and in fact used something similar when I was playing with my big VF display, which takes 1.4A max.  But for development work I prefer having a supply limited to about 1/2 Amp - even less sometimes - that way if I do something silly (which happens not infrequently) then the chances of permanent damage or letting the smoke out of something are a little reduced.  The 78M05 limits at 0.5A or you can even use a 78L05 which limits at 100mA.  I am working (mostly in my mind at the moment I will admit) on a breadborad develoment system - pluggable breadboards and +/-12V and +/-5V power rails, but might think about having various current limited supplies available (maybe even a variable limit on the +5V using the good old 723 regulator).  That way, with my clumsy fingers and addled brain, I will have less chance of frying expensive chips... :-)

Max The Magnificent
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Re: Tasty terminal blocks
Max The Magnificent   1/21/2014 10:44:37 AM
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@David: ...are very good for is to put next to a breadboard for connecting power...

I've started using a 10A switched mode 5V power supply that's really well regulated -- I have four power leads coming of fit each with a 2.1mm male plug on the end -- I can plug these directly into an Arduino -- or in th ecase om my breadboards ech I connect the breadboard to one of those 2.1mm female connectors with two screw-terminals -- so then I can just plug one of my flying power cables into this -- it make slife really simple :-)

Duane Benson
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Re: Tasty terminal blocks
Duane Benson   1/20/2014 2:20:23 PM
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I did see the lever / tension clamp blocks in 0.1" pitch. They were even more expensive than the screw terminals though.

antedeluvian
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Rationale for the price of connectors
antedeluvian   1/19/2014 10:17:24 AM
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Max

 we find that a 10-position block (part number A98074-ND) costs $4.27, a 9-position block (part number 277-1280-ND) costs a whopping $6.04, and an 8-position block (part number A98338-ND) costs $5.29.

This is an extract from my own comment entitled "Torque settings and mechanical design" in my blog "Which PCB Connectors Are Best?"

"The electrical simplicity of the connector belies the complex mechanical design needed. The contact itself is a tradeoff between mechanical strength, conductivity, clearances, corrosion resistance, gas tight,  surface area, regulatory requirements, pressure and vibration resistance. The last item is often covered by a patent. Take a look at the 13th page of this document in the section marked "The principle of vibration resistance".."

David Ashton
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Re: Tasty terminal blocks
David Ashton   1/18/2014 5:46:35 PM
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As an aside, one thing the spring-clamp type of terminals - especially those not requiring a TFS to operate - are very good for is to put next to a breadboard for connecting power or signals.  They make connecting them a pleasure, and you are not tied to having a fixed arrangement.  You can use speaker terminals for this as well, but they are usually a lot bigger - which can sometimes be an advantage if you have five thumbs on each hand like me.



 

antedeluvian
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Re: Tasty terminal blocks
antedeluvian   1/18/2014 5:03:19 PM
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Tony

I think you will find that you and I have a lot of common experience if you look at my blog "Which PCB Connectors Are Best?"

antedeluvian
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Re: Tasty terminal blocks
antedeluvian   1/18/2014 5:00:24 PM
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Max

Are you sure it's not for "Tasty"? :-)

I have heard of sword-swallowers, but screwdriver swallowers? Maybe this is an opportunity for a new career direction.

 

David Ashton
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Re: Tasty terminal blocks
David Ashton   1/18/2014 4:58:13 PM
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@Max.... > Don't talk to me about life being difficult... I'm married! :-)

I'm married AND I have to change delinquent terminal blocks...  :-)

>When I did finally get it together and tried to put it on the cube, I discovered I'd effectively got it "inside out"

Don'cha love it when that happens???

Max The Magnificent
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Re: Tasty terminal blocks
Max The Magnificent   1/18/2014 4:45:11 PM
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@Antedeluvian: Now all you need is a TFS. (T is for tiny).

LOL Are you sure it's not for "Tasty"? :-)

TonyTib
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Re: Tasty terminal blocks
TonyTib   1/18/2014 2:38:59 PM
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I think you were right to go with screw terminals -- they're handy for prototyping because you can pretty much stuff anything in there (of various sizes and amounts) and get them to work, at least for a while (I always tug on both wires if I'm connecting two wires to a screw terminal).


Pretty much all spring clamps will work with stranded wire, but you have to open & close the spring, with a screw driver (which needs to be appropriately sized - and sometimes it's tough to hold the board, use the screw driver, and insert the wire), with levers (which can take a bit of force to operate), or possibly something else, depending on the particular model.

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