Good day All,
I have recently been wondering whether there is any reason to not install resistors vertically. It would save space and so the pcb can be smaller, saving cost.
Would love to get your opinions on this.
I have recently been wondering whether there is any reason to not install resistors vertically. It would save space and so the pcb can be smaller, saving cost.
Would love to get your opinions on this.
I found this --
https://electronics.stackexchange.c...ertically creates,loop formed by the resistor.
Hopefully that helps answer your question.
https://electronics.stackexchange.c...ertically creates,loop formed by the resistor.
Hopefully that helps answer your question.
A vertical orientation could make the resistor leads more likely to bend and break if the unit it's in is roughly handled. The resistor might cool better since all 4 surfaces are upright and exposed to convective airflow. Horizontal mounting might make the resistor's leads less likely to bend with rough handling, but cooling is less likely to be as good due to one side closest to the board having less airflow around it, and overall convection would be not as good. So, choose your poison.
I've done just this in a manufacturing setting. The issue was not cost so much as space and form factor. The assembly was going into an assembly with a dozen other cards, and the size of each card was identical. Similar to the concept of a card that fits into a PC. This assembly had about 3-4x more parts than any other previous card. I would say that the PCB cost itself was not really very important, and that in today's world, the manufacturing cost and ability to use auto-insertion would trump any considerations for cheaper PCB.
It's true that vertical orientation won't be as rugged, so I wouldn't do this for gear going on the road or in a vehicle, but this was going into permanent theater installations, and at the end we potted the entire assembly for intellectual property reasons.
Of course, in today's world, surface mounted components make everything even smaller and cheaper.
Elevate the resistors 1/8" off board or, if it is a new board design place holes underneath the resistor for extra cooling. E
Thanks Eyellings,
Fortunately the unit would not be subjected to rough handling.
But the issue of loop 'antennae' effect does worry me somewhat.
Is this a significant problem in analog ?
Fortunately the unit would not be subjected to rough handling.
But the issue of loop 'antennae' effect does worry me somewhat.
Is this a significant problem in analog ?
For stationary settings, the vertical position would be the best choice for resistor cooling and PCB preservation due to its not being cooked by the hot resistor lying right over it.
Hi Rongon, this was my main concern - but the attraction of saved pcb area makes it really tempting.
Rough handling and heat issue won't happen in this case, fortunately but perhaps it is better to be cautious and design the board for them to be horizontal . . . .
Rough handling and heat issue won't happen in this case, fortunately but perhaps it is better to be cautious and design the board for them to be horizontal . . . .
If this is done, the leads must be properly formed.
https://www.pinterest.com/pin/rf101...-resistor-diodes-inducta--623256035921460817/
And do make the shorter lead as the one connected to the higher impedance node.
https://www.pinterest.com/pin/rf101...-resistor-diodes-inducta--623256035921460817/
And do make the shorter lead as the one connected to the higher impedance node.
Even if all concerns raised here are true, in practice it works without hassles.
Example: doap used in pro consoles in studios all over the world:
https://www.resistanceaudio.com/products/gar2520-discrete-opamp
https://www.fivefishstudios.com/diy/doa17/
I have a diy Tb303 clone ( acid bassline synthesizer) who pcb is done this way too and no issues so far.
It doesn't mean anything in most applications but for precision metrology work you want them horizontal. Mounted vertically the temperature at the ends can be different and lead to uncompensated thermocouple voltages.
Well it depend of your circuit and enclosure, but after having built a number of tube condenser microphone ( where there is high impedance ( up to 1giga ohms resistors on grids) and very tiny signals i'm not concerned this much by the antenae factor. Of course a mic body is a nice faraday cage but... take a look at the kind of things you would have to do for such a thing, this is asking for issue with this kind of 'monstruosity' imho, but... here again it works!
The issue are more about being clean and not letting flux residue or fingerprint ( isopropyl alcool and glove mandatory if you want bass but that's another story...) 😉 -scroll down the link to see built steps:
https://groupdiy.com/threads/telefu...e-microphone-build-thread-d-ela-m-251e.55010/
https://groupdiy.com/threads/neumann-u67-clone-d-u67-tube-microphone-build-thread.50021/
That said it'll depend of your circuit: if you want high bandwidth high slew rate design it can be an issue and could well be an antenae. If your enclosure doesn't shield enough too.
And i would take Rayma advice seriously, if not done right ( with pliyers and leaving enough space between curve and component body) you can damage components.
The issue are more about being clean and not letting flux residue or fingerprint ( isopropyl alcool and glove mandatory if you want bass but that's another story...) 😉 -scroll down the link to see built steps:
https://groupdiy.com/threads/telefu...e-microphone-build-thread-d-ela-m-251e.55010/
https://groupdiy.com/threads/neumann-u67-clone-d-u67-tube-microphone-build-thread.50021/
That said it'll depend of your circuit: if you want high bandwidth high slew rate design it can be an issue and could well be an antenae. If your enclosure doesn't shield enough too.
And i would take Rayma advice seriously, if not done right ( with pliyers and leaving enough space between curve and component body) you can damage components.
Good old Scott Wurcer pointed out that the PCB footprint for a vertically mounted axial resistor, can very often accommodate a surface mount resistor too. Giving you a backup alternative that actually fits your board with no re-layout, when one or the other is on backorder.
I personally use vertical resistors all the time. I even give them a special "symbol" on the schematic, showing which terminal is the abutted straight-thru lead and which is the flying wireloop. Why? So I can arrange to have the really important circuit nodes easily accessible to scope probes and/or alligator clips. For example in the attached schematic, node GINA is accessible via the flying wireloop of resistor R6. Node EVE is accessible via the flying wireloop of resistor R12. Node DAVE can be probed on the flywire of R14, etc. The abutted ends of resistors are much more difficult to probe.
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I personally use vertical resistors all the time. I even give them a special "symbol" on the schematic, showing which terminal is the abutted straight-thru lead and which is the flying wireloop. Why? So I can arrange to have the really important circuit nodes easily accessible to scope probes and/or alligator clips. For example in the attached schematic, node GINA is accessible via the flying wireloop of resistor R6. Node EVE is accessible via the flying wireloop of resistor R12. Node DAVE can be probed on the flywire of R14, etc. The abutted ends of resistors are much more difficult to probe.
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Attachments
I really don't see how this is true except in specific situations.
In my example, all resistors were very low watts (1/8 W or less) as we were handling line level signals from/to op amp circuits. If you are dealing with a power resistor the mass is a lot greater and you really shouldn't place the resistor vertically at all. The use of ceramic lifters are sometimes used to lift the resistor from the PCB to prevent scorching and improve air flow, but the resistor should remain parallel to the pcb.
The issue I have seen is the resistor being bent and shorting against other parts. Doing a U bend on the top wire can also fracture the wire or connection to the resistor body. It shouldn’t happen but I’ve seen it before. I wouldn’t do it on something that is mobile or moved a lot to avoid fracturing the solder connection from the torque of the body sticking out and bouncing. Mind you, I’ve done it with no ill results but it’s not what I want to do if it can be avoided.
The issue of vertically mounted resistors being bent over, shorting to each other and/or other components led me to conduct a simple experiment: so I soldered several
O,5W resistors to a piece of project board and threw it around like a frizby - after several collisions with brick walls, the project board broke but the resistors remained pretty much vertical.
So I am discounting 'rough handling' as a negative, unless unwary, clumsy fingers are accountable for the resistors 'falling over'.
This leaves just the issue of possible induced cross talk and pick up in hostile environments . . . . .
O,5W resistors to a piece of project board and threw it around like a frizby - after several collisions with brick walls, the project board broke but the resistors remained pretty much vertical.
So I am discounting 'rough handling' as a negative, unless unwary, clumsy fingers are accountable for the resistors 'falling over'.
This leaves just the issue of possible induced cross talk and pick up in hostile environments . . . . .
Of course, if power is tiny, then the whole concern about cooling is moot.