Hiya,
Looking at SMD components to minimize area on PCBs, but kind of lost in what components to use.
In particular I want to add some caps/ferrites to stop noise/oscillations and wanted to know if I should go for PPS caps for the 10nF/100nF, and what to look for for ferrites. In through-hole components I am using MKP for the caps, ferrite beads on some wire and 150R tantanlum resistors but this takes up more space than I would like (even when using resistors/ferrites vertically.
Not sure what to look for in SMD equivalents. Anyone with experience in SMD components?
Looking at SMD components to minimize area on PCBs, but kind of lost in what components to use.
In particular I want to add some caps/ferrites to stop noise/oscillations and wanted to know if I should go for PPS caps for the 10nF/100nF, and what to look for for ferrites. In through-hole components I am using MKP for the caps, ferrite beads on some wire and 150R tantanlum resistors but this takes up more space than I would like (even when using resistors/ferrites vertically.
Not sure what to look for in SMD equivalents. Anyone with experience in SMD components?
Murata BLM21PG decent? I think I saw it linked in some other topic about ferrites. 2A/220R, 3A/120R It's just for small signal tubes up to 1.2A or there abouts.
https://nl.farnell.com/murata/blm21pg221sn1d/ferrite-bead-0805-0-045ohm-2a/dp/1515661
https://nl.farnell.com/murata/blm21pg221sn1d/ferrite-bead-0805-0-045ohm-2a/dp/1515661
For capacitors probably the lowest distortion readily available type are PPS or C0G ceramic, but they can be bulky for high values. Type-II ceramic distort a lot, they are not for the signal path. SMT electrolytics are readily available for larger values, but I'm not sure bipolar electrolytics exist in surface-mount packages.
For SMT resistors thin-film means metal-film, thick-film means metal-oxide. Thin film have lower distortion, but many times more expensive (although that's not actually that expensive!)
For single-sided boards zero-ohm resistors in larger sizes like 1206 make handy cross-over links. Zero ohm SMT resistors are a thing, they are actually a few milliohms of course, but notionally zero.
Murata make a lot of magnetics, they are reputable, but you have to understand your requirements and the device datasheet to figure out if something is suitable.
SMT devices have to survive a reflow oven, whether a particular sub-miniature tube would be happy I've no idea. They have a lot of thermal mass which means they are likely not to be surface-mounted as it would take longer than other components can tolerate.
For SMT resistors thin-film means metal-film, thick-film means metal-oxide. Thin film have lower distortion, but many times more expensive (although that's not actually that expensive!)
For single-sided boards zero-ohm resistors in larger sizes like 1206 make handy cross-over links. Zero ohm SMT resistors are a thing, they are actually a few milliohms of course, but notionally zero.
Murata make a lot of magnetics, they are reputable, but you have to understand your requirements and the device datasheet to figure out if something is suitable.
SMT devices have to survive a reflow oven, whether a particular sub-miniature tube would be happy I've no idea. They have a lot of thermal mass which means they are likely not to be surface-mounted as it would take longer than other components can tolerate.
I was kidding with the sub-miniature tubes. The PCB goes onto a noval socket actually, wanting to make PCBs to fit some high-gm tubes. Not everything needs to have a SMD e1quivalent, I thought BB was kidding. 😀
Thanks for the advice on the R/C/L components.
Thanks for the advice on the R/C/L components.
Some (potentially unwelcome) advice: When choosing and placing SMD parts for tube circuits, make sure you maintain the required spacing for clearance and creepage for your situation. This applies both to part-to-part spacing and to the terminal spacings within any given part. It's easy to ignore voltage ratings for e.g., resistors. But even if you don't, verify. A part may be able to withstand higher voltages than is considered safe for the clearance between its terminals.
When you look at the second picture here:
https://www.tnmoc.org/colossus
you see that the valve holders of the rebuilt Colossus are in a sense surface mounted. Their terminals don't go through holes in the mounting panel, the connecting wires are on the same side as the valves.
https://www.tnmoc.org/colossus
you see that the valve holders of the rebuilt Colossus are in a sense surface mounted. Their terminals don't go through holes in the mounting panel, the connecting wires are on the same side as the valves.
This is as bad as SMD USB connectors. The only pro is cheaper production - not an issue with DIY
I think the main advantages were that they could put valves on both sides of the panel, and that they could see better what they connected to what. Connecting up 2500 valves correctly is quite a challenge.
You guys building Eniac 2000 or something?
@lauda Indeed. These parts are for the filaments mainly, so they should not go above 6-12V in my case.
I've been playing around with the SMD caps, but they are not that much smaller than the through-hole variants. In my case it would only make sense for the ferrites. Not sure on the sonic quality of the SMD resistors, so that grid stopper will stay through-hole as well.
SMD seemed a good choice to keep it small, but it's turning out to not be that beneficial.
@lauda Indeed. These parts are for the filaments mainly, so they should not go above 6-12V in my case.
I've been playing around with the SMD caps, but they are not that much smaller than the through-hole variants. In my case it would only make sense for the ferrites. Not sure on the sonic quality of the SMD resistors, so that grid stopper will stay through-hole as well.
SMD seemed a good choice to keep it small, but it's turning out to not be that beneficial.
No, the computer I linked to is a rebuilt Colossus Mark II. Colossus was both older and simpler than ENIAC, and unlike ENIAC, it actually helped the allied forces win World War II.
Anyway, in a sense, it has surface mounted valve holders. That's the one and only relation to the present topic.
Anyway, in a sense, it has surface mounted valve holders. That's the one and only relation to the present topic.
You know about peg-and-paste? Through hole components that can be pick-and-placed as SMD devices? Makes a big difference. The pegs extend 1mm or so into the holes but that's enough to engage with the through-hole-plating surface solidly.
I can make anything Surface Mount with a roll of Duct Tape, but not quite was I was after in this topic 😉
For instance a peg-and-paste USB C plug: https://www.mouser.co.uk/datasheet/2/1628/up20_c_f_g_fl_p12_tr-3511345.pdf
The contacts are SMT and the mounting pegs are short through-hole tabs. This can be pick-and-placed as if SMT and doesn't need wave soldering
I know these USB connectors. But I do not consider them as close as robust as their THT counterparts.