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A thing that I really miss in Kicad is the ability to quickly add zero-ohm resistors when editing the PCB layout while not modifying the schematic. Indeed, when
by Faaak 8y ago
A thing that I really miss in Kicad is the ability to quickly add zero-ohm resistors when editing the PCB layout while not modifying the schematic. Indeed, when you do your own boards in house, it's really convenient to add a zero-ohm smd resistor for jumping over a trace, without having the need to go and edit the schematic..
- bronson 8y agoBut then your BOM, PCB, and schematic wouldn't match. Somewhat like automatic code formatting, disallowing this sort of divergence seems more a feature than a misfeature to me. Even for in-house use.
- starbeast 8y agoSome bit of my head is a zero ohm resistor resistor. Every time I read 'zero ohm resistor', it goes 'nope nope nope' at me.
- analognoise 8y agoWhy not? They're great as test points and you can pull them off and place a resistor or capacitor in their place.
- Mindless2112 8y agoProbably because the operating temperature is about 0 Kelvin.
- starbeast 8y agoI guess it doesn't have to go quite that low, depending on what you make it out of. Though you have got me wondering whether anyone has put a crumb of high temp superconductor in a smd resistor package yet and if so, for what purpose.
- gh02t 8y ago"High temperature" is relative, they still have to be cryogenically cooled to temperatures around -100C. So no SMD superconductors yet.
- starbeast 8y agoThat is still a relatively accessible temperature, given that liquid nitrogen is about the same price as clean water. Off the top of my head, I could think of one use, which would be to trigger a transistor to switch on and off some high power superconducting circuit when the small bit of superconductor gets cold enough to start superconducting.
- wolfgang42 8y agoI assume it's the paradox of a resistor that doesn't resist.
- blt 8y agoThink of it as an "epsilon ohm resistor".
- starbeast 8y agoHeh, I like that. I tend to think of them as a surface mount jumper.
- cellularmitosis 8y agoMy 1/4W THT zero ohm resistors are about 0.025 ohms according to my bench meter. In theory, that implies a 400 amp rating... not going to try that anytime soon :)
- amyjess 8y agoIt's zero in the number of significant figures used by the test equipment.
- amelius 8y agoThat's a pity because then you can't use that resistor to measure current by a measurement of a voltage difference.
- ssfrr 8y agoThey make high-precision low-resistance resistors specifically for current measurement. Your standard cheapo zero-ohm resistor though is more for creating optional connections that you can configure at assembly time.
- ajnin 8y agoYou can just create a PCB with one additional layer and use that layer (top one for example if you make single-sided pcbs at home) for jumpers, then to add a jumper while routing a trace, switch layers, which will add a through-hole via, trace your jumper, then jump back to the initial layer through another via. When etching the board you omit that layer and later solder wires where the traces were. It's quite flexible as you can add jumpers of any length and orientation that way, the only inconvenient is that jumpers aren't marked on the silkscreen but it's fine for home-made projects.
- blattimwind 8y agoThis is the correct-ish way if you don't plan to actually populate zero-ohm resistors from a BOM.