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New Breadboard Adaptor PCBs

Adaptor PCBs

Scott over at Curious Inventor had some space on a multi-project PCB he was sending to Gold Phoenix and offered to do some boards for me. I whipped up several adaptors for my solderless breadboard projects. Its always a great feeling to see your projects turned into real PCBs!

In the picture here you can see six new PCB boards, the two small ones on the far right are actually Scott’s that he sent over for me to check out. The parts are also shown.  The tiny one is a tip jack adaptor and the other is a stereo headphone mini jack like the one on your PC.

My boards from left to right are, MIDI In, MIDI Out, Terminal Adaptor, and Mini Prototype board adaptors. Each of the boards is build up in the picture below

Why Adaptors
We constantly run into trouble interfacing via connectors and to devices that have stranded wires. Some interfaces are common and it would be nice to have ready made adaptors for these as well.

To make things easy and to use PCB board space efficiently I settled on a standard size of 0.75 inches by 1.50 inches. This gives space for seven (7) tenth-inch spaced connector pins and I included the two pin headers that connect into the power rail. The two pin headers help support the board when its plugged in to the breadboard.

Adaptors on Breadboard2

Here are the adaptors all build up and plugged into a small breadboard.

AudioAndTipJackAdaptorHeadphone Jack Adaptor
This small PCB done by Scott at Curious Inventor just has three pins to plug in, Left, Right and Ground. Using this adaptor you can connect audio sources or outputs from your breadboard. Finally I will have a nice way to get audio in and out of my projects. In the past I have used a scrounged connector that kept popping off the breadboard because its leads were two short.

Tip Jack Adaptor
The little black thing on the tiny PCB is a tip jack connector. This accepts the probe tip from your typical DVM. Instead of finding a clip lead or trying to hold two connections at once you can plug in this little adaptor to connect your meter.

At first I did not think this would be all that handy but now that I have build it I am sure it will be very handy.


Mini Prototype Board Adaptor
This one lets you build small circuits to reuse on your breadboards. I did it first as a quick use of the base PCB design for all the adaptors. It would also work well for 0.1 inch spaced parts. The pads are connected much like the solderless breadboard. The power rails are passed down the center of the board and the two rows are connected so that you can reach the signals of a 0.3 inch spaced IC and the seven pin connector.

I plan to build up an adjustable current sink circuit I tend to use often in my projects to test power supplies and LEDs for my first use of this adaptor.

Screw Terminal Adaptor
TerminalAdaptorPCB Includes two screw terminal adaptors. I wanted to have something to adapt wires to the breadboard and my chosen from factor seemed large for a single terminal strip. With this adaptor you can connect four separate wires to the breadboard without soldering up some kind of adaptor to plug them in. This adaptor will be ideal to hook up a pair of speakers for some audio work I plan.

MIDI In and MIDI Out Adaptors
The last two adaptor boards are much more advanced. The MIDI Input adaptor includes the 5-Pin MIDI connector and opto-isolator. The same is true for the MIDI Output Adaptor. Both of these boards adapt a MIDI interface for connection to a microcontrollers TX and RX UART pins. A MIDI enable signal is also supported so its easy to share a serial port with MIDI and other communications functions.

MidiInAdaptorPCB MidiOutAdaptorPCB

I had trouble using MIDI and the boot loader at the same time on the Arduino so I came up with a method that lets the serial port be shared for both purposes. I explain more about the enable controls in a future article about these MIDI adaptors. The key here is that they are disabled automatically by RESET so that MIDI input signals do not interfere with the boot-loader serial data. MIDI out is also disabled so that MIDI devices are not confused by the serial data coming from the PC during the boot-loader process.

Great, I want them!
These are not for sale yet, I may just give them away here at uCHobby for links or articles. I have about 10 of each of these adaptor boards and very few of the audio and tip jack adaptors so those are spoken for. At some point I hope to have a collection of adaptors for sell in a package but that is not ready yet.

I have not completed testing on these adaptors, really have just finished building up one of each and making notes of things to improve. Assuming they all work I will give some away in a contest. Read on down…

Well there are a few things that need to be improved on these boards. This was a small run of 10 each and nothing major has been found wrong yet.

  • Reference designators are hard to read on some of the components. Standing Resistors are easy to confuse
  • One of the two pin power rail connectors is off by 0.005 in placement causing the boards to angle a bit when plugged in.
  • The character spacing is two tight on the uCHobby and Curious Inventor text on the terminal strip board.
  • Power rails should not be connected on these adaptors. Doing so makes it so the board can only be plugged into one side of the breadboard.

Comment Contest and Giveaways
I will giveaway 5 sets of these boards for winning comments. Each set will have one MIDI In, MIDI Out, Screw Terminal, and Proto Adaptor. This will be the PCB only, no parts. Three will be given away randomly for any comment that meets the guidelines and two will be given based on quality of the comment. In other words, I will select two of my favorite comments to receive a set. I’m looking for comments that will improve these adaptors, suggestions for future adaptor boards, and project ideas that would benefit from these adaptors. Winners will be picked on February 1st 2009.

You can also request a set of these boards as part of the normal uCHobby Giveaway Program.

Posted in Contest, Parts, Projects, Workshop Tools.

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12 Responses

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  1. Cail says

    Fun stuff. I second the right angle pins in order for the boards to stand upright (where it makes sense to do so, of course). Also, to @Mikael’s comment, if you could add in one through-hole in each corner opposite the side with the breadboard pins, you would have the option of soldering in single pins in order to provide some support to the other side of the board. The pins obviously don’t trace to anything on the PCB…they just act as standoffs.

    What about creating the breadboard pin traces such that a GND and/or VCC pins are staggered a bit back from the normal pins, so they can be directly connected to the common rails while the normal pins connect to the common center prototyping area? That saves some jumpers connecting the rails to the pins.

    I’d like to see a moduletronics that has 4 or 5 small PCB pushbuttons, arranged in D-pad layout, for simple input. Rather than just lining up five pushbuttons in a line (like many boards do), a D-pad layout gives some extra directional meaning (up/down, left/right, and a select in the middle).

    Also, it seems you can never have enough UART/TTL to RS232 adapters laying around. I’d love one that combined all of the comments above (stood upright and connected into common rails, but done ‘sideways’). You can see a cheesy sketch of what I mean at

  2. Miroslav says

    Great job. Headphone Jack Adaptor is my favorite, so small and so handy :). I would really appreciate breadboard adapters for potentiometers and rotaty encoders. They would be very useful because potentiometers and rotaty encoders usualy don’t fit to breadboard.

  3. Randall Bohn says

    These look great. I think I would put right angle pins on some of the modules so they could stand up vertically on the prototype board. I’m planning to get the current sink fabbed later this month. It might keep me from frying more on-board LEDs.

  4. Joseph Yumul says

    You can also make some tiny breadboard adapter for passive components such as resistors and diodes making them more reusable on breadboard prototypes cause you avoid damaging their pins :D

  5. Mikael says

    These look like really nice “utility” boards.

    A good idea is to add some of those self adhesive rubber feet to the end of the pcb’s that is “floating in air” so any heavy cables connected to them will not tilt the entire breadboard. But maybee there’s no room for them ?

  6. Berni says

    I already have a few SMD adapters ready on some trasparacys so when i need one i can etch it quickly

    Oh and if we are talking about MIDI, I once tryed out with a simple wavetable synth with a dsPIC. It could play multiple tones at the same time, generate almost any signal (prerecoded samples),generate white noise and it could also do effects like reverb. Also it has a 0 external component count. Internal oscilator and internal stereo 16bit DAC

  7. dfowler says

    @Berni: Planed on doing SMT adapters as well as a few types of interfaces.

    For my MIDI project, I want to generate some music based on ambient measurements. Like a Therimin but controlled by some ambient parameter. Hard to explain in a short comment.

    @Shawn: We have a power supply adapter which is sold at Curious Inventor.

    Working on a new +/- adjustable that should be available soon as well.

    Will have a 1 Watt audio amp, an audio input/mixer board that supports line or mic inputs and a few othrs planed as well. I want to design up a bunch of these adapter modules.

    @Mike: Moduletroincs is what I’m aiming for. Rather then have a big board with lots of interfaces and a small protytping area, the idea is reversed, you use a big solder-less breadboard and plug in the interfaces and gizmos you want to play with.

  8. Mike says

    When I’ve been dreaming of making “handy” PCBs, doing a SMT-to-breadboard for several package type has been top of the list. Places like Digikey sell, for example, PLCC to breadboard adapters, but the last time I looked, they were horrendously expensive and clearly targeted at businesses with very deep prototype pockets.

    Also, building small breakout type boards like you did would be handy to apply to things like small power supplies, RS232 adapters, etc. Kinda like Legos but for breadboarding. Moduletronics :^)

  9. Evil Paul says

    Wow, I can see myself using every one of these adaptor designs, nice work. In fact, next time I sit in front of a breadboard I will feel a bit miffed that I have to use regular old solid core wire and clip leads to hook stuff up ;-)

    The MIDI I/O is definitely the most interesting, I’m looking forward to the upcoming article.

  10. Shawn Vincent says

    One of the most useful breadboard PCs I can imagine is a regulated power supply, run off a wall wart. Lots of people could benefit from this.

    My favorite one you’ve built here is the mini prototype board. Really, for most little circuits you could want (including my idea), that would be fantastic!

    Really good idea. Thanks!

  11. Berni says

    Well you could also do adapters for chips and such that dont fit in a breadboard like SMDs (All the good stuff seems to be becoming SMD only)

    Im curious tho what are you making with MIDI.

    You can be happy with the errors on your boards.Yesterday i made a board for my PIC oscilloscope and some of the pins on the 0,5mm TQFP64 got bridged together.Gah the frustration!

Continuing the Discussion

  1. Using Adaptors and IPhone for Audio Breadboard Work | uC Hobby linked to this post on January 19, 2009

    […] I wait for the second round of PCBs for the breadboard adaptors, I started working on the next adaptor design. The first pass adaptors came in very handy while […]