The world of DIY circuits for STEM and wearables has a few options for conductors. Wire with Dupont connectors is a standard, as is adhesive copper tape. There’s also conductive nylon/steel thread or ribbon. Which you choose depends on your application, of course, but as a general rule wire is cheap and ubiquitous while making connections is more challenging; copper tape is cheap and simple to use, but delicate and rips easily, so is best used for flat surfaces that won’t see a lot of stress or temporary applications; and conductive nylon thread or tape is better for weaving into fabrics.
The Brown Dog Gadgets team wanted to respond to a frequent question they are asked, what are the current limits for their Maker Tape (nylon/steel ribbon), so they ran some experiments to find out. In the name of Science you’ll see some flames in the video below, but only under extreme conditions.
You may already have bits of each of these options lying around in your bins, and if you don’t it may be worth it. Each connection option has its benefits.
| Wire | Copper Tape | Nylon/Steel Tape | |
|---|---|---|---|
| Insulation | Yes, must be removed to connect | None, and adhesive backing is sometimes conductive | None |
| Solderability | Usually great (not for some wires) | Great | Not at all |
| Resistance | <.1ohms/ft | <.1ohms/ft | 5-15ohms/ft |
| Reusability | Yes | No | Yes |
| Flexibility | Yes | No | Yes |
| Ease of connecting | Crimp, solder, twist, spring, press | Solder, adhesive, press | Twist, tie, spring, press |
| Cost | Cheap | Less cheap | Least cheap |
| Application | Any electronics | Temporary delicate projects | Fabrics, less delicate projects |
Their scientific process yielded sound results. While not as capable as copper tape, which could easily handle 5A (the limit of their power supply), their Maker Tape endured 3A before the adhesive started to struggle, and at 3.5A the tape acted like a fuse and burned itself out. It was only under very specific unusual conditions that took them a long time to recreate that they were able to get flames. For them this was a huge success, as most of their users are powering their circuits with coin cell batteries and only driving a motor or some LEDs, and this current consumption was at least an order of magnitude greater than most of their use cases. Anyone trying to use the nylon/steel tape at the level that can fry the tape likely knows what they’re doing enough to avoid the potential problem.
Incidentally, if you’re wondering why wire rating is measured in amps and not watts, here’s some physics. Power = Current * Voltage, and Voltage = Current * Resistance. These are the two formulas we all learn from the beginning of electronics lessons. When it comes to wires, resistance is measured as ohms per length. What we’re interested in is not the power that can flow through the wire, but the amount of power that the wire can safely dissipate before failing as it heats up through its own resistance.
Doing some algebra, Power dissipated by the wire as heat = Current*Current*Wire Resistance*Length. We don’t need the voltage. But also notice that if the length doubles then the power dissipated by the wire doubles but so does the amount of surface area of the wire to dissipate that heat. If you were to rate a wire by power, you’d have to include the length. To simplify things and keep the length out of the rating, and relate the rating back to how much energy is transferred across the wire (and not dissipated by it), and since source voltage doesn’t matter, the wire is thus rated with the amount of current.
[youtube https://www.youtube.com/watch?v=3Vt0bbB_A-w?start=5%5D
Conductive tape used to be used as window break sensors in alarm systems. Used to be a common thing to see a shiny line about 1″ away from the edges of windows in businesses. Look up near the top to find a gap with a couple of wires attached to the tape, leading off somewhere to the alarm system installation. That shiny line also served as a deterrent to smash and grab criminals.
Then along came cheap motion sensors and audio sensors to listen for the sound of breaking glass.
That stuff wasn’t supposed to be very durable though, beyond staying stuck to the window. Think it was just basically thin foil aluminum tape.
“Dupont connectors”
There is no such thing as a Dupont connector.
Jumper DuPont wires: a practical solution for Arduino and breadboards. … Well, their name is dupont wires, or rather DuPont. This name is derived from the manufacturer of the connector type they mount, both male and female end.Dec 5, 2013
A quick google search would show you that you’re wrong about that.
Sure, dupont doesn’t make them, but jumper wire hookup cables have been called that for ages, and it’s an easy way to reference them that will get a ton of results for people who are looking to find exactly what Bob was writing about.
Yeah at least DuPont still exists as an independent entity. They may not make them anymore but they sure used to. Are we going to need to find a new name for every connector now when its creator invariably gets rolled up into a publicly held multinational and bled out by the private equity vampires? We’re going to need a lot of new names. RCA, Philips, (Molex surprisingly still exists but as a subsidiary of Koch Industries the vampires can’t be too far away), DIN, DB9 (now an Aston Martin), everyone else in the EE graveyard we could be doing this a while and it’s going to get confusing
DE9. There is no such connector beast as a DB9. The D is for D-Subminiature. The second letter is the size. B is the size for 25 pin serial and LPT ports. A was used for PC joystick and old Macintosh monitors. E is for 9 pin serial ports and various PC monitors. The 15 pin VGA connector is commonly called HD15. H for High Density. It should be called HDE15.
You are technically correct, Hermes Conrad.
I’ve been around long enough that they were generically called Berg connectors.
LOLno. Berg connector is the power connector on a 3.5″ floppy drive. Wiki it dude.
> Anyone trying to use the nylon/steel tape at the level that can fry the tape likely knows what they’re doing enough to avoid the potential problem.
I disagree. It’s very easy for hobbyists to overlook capacity ratings of parts; especially for things where they’re scrounging through their junk box for a part that’s “close enough”.
Also, a circuit can be built to an originally designed capacity, but then added on to until it exceeds the capacity of the original wires.
It’s all fun and games until someone decides to add several thousand lumen “head lights”
You can soft solder stainless steel, you just need the proper flux. Superior #71 flux works great: https://superiorflux.com/spec/TDS_No_71.pdf