EMRFD Message Archive 9526

Message Date From Subject
9526 2013-12-05 06:25:58 mm0gyx SMT np0 capacitors
Is anyone using smt capacitors for ugly construction, do they suit the style of build?
They are much cheaper in bulk pack here in the uk than leaded ones.

Ian mm0gyx
9527 2013-12-05 06:33:56 Tayloe, Dan (NSN ... Re: SMT np0 capacitors

Yes, but these caps are physically fragile.  In one case I mounted them vertically on end and used these to support other small parts mid air.  Under such conditions they tend to break.  However, they work well if both end of the cap are well supported such as leaning against a “dead bug” IC pin to a PCB ground plane.


When I have needed to mount the cap vertically and also provide support, I have taken a “nibbler tool” rectangular piece of PCB board and but the copper in the middle isolating the foil on either end.  I have then mounted the cap to this PCB piece and used that to provide mechanical strengthening to the cap.


-          Dan, N7VE


9529 2013-12-05 07:07:50 Nick Kennedy Re: SMT np0 capacitors
I think the SMT parts mix well with Manhattan style.  They lean from a pad to ground pretty well, and pad to pad if you make sure your gap is right when you glue them down.


Nick, WA5BDU
9530 2013-12-05 07:09:51 Tayloe, Dan (NSN ... Re: SMT np0 capacitors

I should also mention that SMT resistors seem *very* sturdy.  The only parts that seem fragile are the SMT caps.


-          Dan


9531 2013-12-05 07:31:26 WA0ITP Re: SMT np0 capacitors

I've used them in Manhattan constructions and they worked fb, same for smt resistors of course.
Real radios weigh less than a pound.
I love this radio stuff !
72   WA0ITP
----- Original Message -----
9535 2013-12-05 10:33:52 EricJ Re: SMT np0 capacitors
Great idea.

I just made a dozen of them by precutting and removing a line of foil from a piece of scrap PCB, then nibbling down the PCB with the line centered on the tool. I soldered on a few common value caps to keep handy.

So to the OP, I don't like to use SMTs unless I have to. They work fine, but always take more work to do the simplest things, particularly if you are of a certain vision-challenged age. So I don't think the savings in cost justifies them for one-off construction. If you can't afford a 50 cent part, can you afford a 5 cent part? A worthwhile consideration when you are building a million units, but maybe not for just one hand-built unit.


9536 2013-12-05 10:54:52 Tayloe, Dan (NSN ... Re: SMT np0 capacitors

I love SOIC (0.05” spacing) for deadbug prototypes.  DIPs are too large(0.1” spacing) and TSOP (0.02”?, the next step down in size) is too small except if that is all I can get. SOIC certainly helps fit a lot more into a small space.


To match the smaller parts (including 1/8th watt or 0805/1210 smt resistors), I use #30 gauge enamel wire for hookup.  Just burn the enamel off the ends in a solder blob.  That works well for hooking up about everything until you get to the driver/final of the transmitter.


I only tend to use SMT caps when I am out of stock on the leaded parts.  However, I do like that it is much cheaper to buy 25 or 100 SMT caps than the through hole parts.

-          Dan, N7VE


9541 2013-12-05 16:08:49 mm0gyx Re: SMT np0 capacitors

Thanks for the replies everyone. I think it's worth it for the saving in my case. It's getting increasingly hard to get hold of leaded np0 caps here in UK. They tend to cost more than 50 cents, things on our side are in pounds & pence and we tend to pay more for equivalent items. I plan to build more than one hand made unit too.


Ian mm0gyx