[TriEmbed] Giving this Surface Mount Thing a Try - Transistor Help Needed

[The MacDougals]

Since you are collapsing all of the breakout boards, what are your plans for
the processor?

As I recall, the reason for having to invert the signal was due to a
limitation on the external

interrupt pin of the processor.  Newer Atmel chips have pin change
interrupts on all pins

and can handle either edge.  So, if you go with an ATTiny 84 or similar, you
don't need the transistor.

 

---> Paul

 

 

From: TriEmbed [mailto:triembed-bounces at triembed.org] On Behalf Of Charles
McClelland
Sent: Friday, March 21, 2014 3:47 PM
To: Glen Smith
Cc: TriEmbed Discussion
Subject: Re: [TriEmbed] Giving this Surface Mount Thing a Try - Transistor
Help Needed

 

Glen, 

 

I am using EAGLE - it allows you to set the names so I guess I have to take
responsibility  - Resister Base (RB)  - I am learning so if there is a
better naming convention I should be using, I would be open to it.

 

Thanks,

 

Chip

 

 

On Mar 21, 2014, at 1:29 PM, Glen Smith <mrglenasmith at gmail.com> wrote:





Charles,

As Bill said, there are single gate IC's to do what you want, a quick glance
indicates the cheapest (in one'sie two'sie quantities) is $0.33. But there
are 2222 transistors available in SOT-23 packages: Jameco has them here: 
http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDrillDownView?la
ngId=-1
<http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDrillDownView?l
angId=-1&storeId=10001&catalogId=10001&freeText=2222%20sot-23&search_type=ja
mecoall>
&storeId=10001&catalogId=10001&freeText=2222%20sot-23&search_type=jamecoall 
qty 10 available at $0.09 each. Or, to keep the comparison, DigiKey has them
here: 
http://www.digikey.com/product-search/en?pv7=2
<http://www.digikey.com/product-search/en?pv7=2&FV=142c0042&k=MMBT2222A&mnon
ly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25>
&FV=142c0042&k=MMBT2222A&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity
=0&ptm=0&fid=0&pageSize=25 
(for one'sie two'sie quantities) at $0.18 each.

It has been far too long since I did transistor circuit design to tell you
whether what you have will do the inversion you want, but you can hook it up
on a breadboard with your discrete's and see how it works.

Since I'm sending this note anyway, is there a reason why you chose RA, RB
RC designations? It took me a few minutes looking at your circuit to figure
out that it was a designator rather than a ResistorCapacitor (RC) network.
Maybe it is just what I'm used to working with. Which layout tool are you
using? KiCAD or Eagle? If one of them forces me to use RA, RB, RC - I think
I will use the other.

Glen

 

On Fri, Mar 21, 2014 at 12:46 PM, Bill Farrow <bill at arrowsreach.com> wrote:

Charles,

There are single logic gate ICs in surface mount which should do what you
want. Here's my quick digikey search.

 

http://www.digikey.com/product-search/en?pv247=24
<http://www.digikey.com/product-search/en?pv247=24&pv64=1&pv667=1&pv69=3&FV=
fff40027%2Cfff8019d&k=single+gate&mnonly=0&newproducts=0&ColumnSort=0&page=1
&quantity=0&ptm=0&fid=0&pageSize=25>
&pv64=1&pv667=1&pv69=3&FV=fff40027%2Cfff8019d&k=single+gate&mnonly=0&newprod
ucts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

 

 

Bill

 


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