I'm trying to connect an IR sensor to an Adafruit Feather Huzzah microcontroller module without soldering the pins on. The sensor has a power supply of 5V which I have connected to the USB pin of the microcontroller as shown below. I don't have access yet to a breadboard but I want to try and get some data as soon as I can.

Arduino Featherboard Huzzah

Using Jumper Wires

MLX90614 Infrared Thermometer

My first question is whether the electrical connections will work without soldering?

Secondly, am I using suitable cables for the connection to the sensor since although it goes all the way in, it is quite easy to pull out. This may be a problem since they may come out during application.

And finally, while writing this question, I found that the USB gets regulated down to 3.3 V so I need to use a power supply at 5 V. Is there a quick fix for this or will I have to just have to wait until the breadboard arrives and then connect it to a battery?

Also, what are these cables called?


3 Answers 3


My first question is whether the electrical connections will work without soldering?

Probably, but not very reliably.

the USB gets regulated down to 3.3V so I need to use a power supply at 5V. Is there a quick fix for this

Use the USB voltage directly instead of going through the regulator. If necessary, cut the USB cable open, measure the wires, and use the ones with 5V between them.

Note that if you short the output, the USB output of the USB power supply or computer might get damaged. And of course, if you apply 5V to inputs that expect 3.3V, the inputs may become very unhappy.

what are these cables called?

Many things. Breadboard wires, jump/jumper wires, Dupont wires, to name a few.

  • \$\begingroup\$ Thanks, I'll be needing a breadboard to bypass the microcontroller right? Also, these jumper wires click into place onto the pins of the microcontroller but not onto the sensors pins? Should I be using different wires? \$\endgroup\$
    – Yogi12
    Apr 24, 2018 at 12:35
  • \$\begingroup\$ @Yogi12 You need to be completely clear here. You're doing something which most people won't, using push-fit wires which were not designed for the job you're doing. This is a temporary quick-and-dirty kludge, and as Dampmaskin says, it will never have reliable connections. "Should you use different wires?" No, really you shouldn't do it this way at all! If it's expedient to do it this way as a temporary hack, these are the consequences. \$\endgroup\$
    – Graham
    Apr 24, 2018 at 12:47
  • 4
    \$\begingroup\$ The actual problem even before any question about the jumper wires is that the asker hasn't soldered the header pins to the MCU module; they're supplied loose in a bag, and must be soldered by the buyer. \$\endgroup\$ Apr 24, 2018 at 14:11
  • \$\begingroup\$ Well spotted. :o \$\endgroup\$
    – Dampmaskin
    Apr 24, 2018 at 14:17

No, this is not generally workable.

The jumper cables are okay for temporary setups. The problem is that before you can use jumpers, you must solder the header pins to the module circuit board. The true meaning of "without soldering the pins on" in the text of your question becomes apparent when looking closely at the picture showing that you have not soldered the headers to the board. This is a common beginner temptation which is unworkable; through hole header pins are made to be soldered and will achieve at best intermittent contact without that (the solitary exception would be that a single, short single row header can be held at an angle with finger pressure for a temporary programming connection if mid-programming failure is known to be recoverable)

Once your headers are soldered onto the module, you can indeed use jumper cables if they are functional, make reasonable contact with the component pins as well, and the signals involved are relatively low speed such that the lead length does not become an issue. Another handy solution is to use a wire-wrap tool and wrapping wire to connect to headers - the old style headers intended to support up to three wrapped connections were far longer, but ordinary length headers will support a single connection.

Or you can solder wires directly to the module instead of installing the headers.

But unless you are using something like spring contacts in a test fixture, you must solder either pins or wires to the MCU board, and then make appropriate connections from there.

  • \$\begingroup\$ Ha, wow, good catch. \$\endgroup\$
    – Samuel
    Apr 24, 2018 at 17:23

For testing the cables will probably be suitable, for permanent applications or some proof of concept I would definitely recommend something a little bit more mechanically stable, by soldering it on some quick prototyping board

The huzzah feather has an usb pin which will be 5v if the usb is connected

USB - this is the positive voltage to/from the micro USB jack if connected

note that eventhough you can get 5v directly from the micro usb the GPIO pins of the microcontroller will still only handle 3.3V max

The cables are called jumper cables (male-male) (male-female) (female-female)

enter image description here

  • \$\begingroup\$ This is a different board in the Feather series than the one the question is about, though the supply connections may be the same. \$\endgroup\$ Apr 24, 2018 at 14:16

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